United States
Environmental Protection
Agency
EPA/600/R-07/075
April 2007
Atlanta Commute Vehicle
Soak and Start
Distributions and
Engine Starts per Day
Impact on Mobile Source
Emission Rates
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EPA/600/R-07/075
April 2007
Atlanta Commute Vehicle Soak and Start Distributions
and Engine Starts per Day: Impact on Mobile Source Emission Rates
by
Randall Guensler
Seungju Yoon
Hainan Li
Vetri Elango
School of Civil and Environmental Engineering
Georgia Institute of Technology
Atlanta, GA
Contract No: EP-05C-000127
EPA Project Officer: SueKimbrough
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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This page left blank deliberately.
11
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ABSTRACT
The Georgia Institute of Technology (Georgia Tech) School of Civil and Environmental Engineering
research team analyzed the 2004 second-by-second vehicle activity data obtained from vehicles in the
Atlanta Commuter Choice Value Pricing Initiative, otherwise known as Commute Atlanta. The onboard
monitoring equipment installed in each participating Commute Atlanta vehicle records each second of
vehicle activity. Hence, each engine event (engine on, engine off) is time-stamped to provide the start and
end times of each vehicle trip. The times of each trip end can be used to directly quantify the number of
engine starts per day, the start times for each trip, and the durations of soak times between trips. (The soak
time affects exhaust start and exhaust running emissions. A vehicle is considered to be soaking if its en-
gine is not running. Soak time is the length of time between the engine turn off time and engine start time.
Cold soak time in MOBILE6 determines the percentage of vehicles that have been soaking for a given
amount of time prior to an engine start, for each hour of the day. The hot soak time distributions represent
the proportion of vehicles experiencing a hot soak of a given duration at each hour of the day.) For the
purposes of the analyses presented in this report, the research team followed the same criteria U.S. Envi-
ronmental Protection Agency (EPA) used to develop soak and start time distributions and engine starts per
day in the MOBILE6.2 emission rate model (U.S. EPA, 2001; U.S. EPA, 2003).
The objective of research efforts reported herein is to develop gasoline vehicle soak and start time distri-
butions and engine starts per day for EPA light-duty vehicle (LDV) and light-duty truck (LDT combining
LDT1, LDT2, LDT3, and LDT4) classes using vehicle trip data collected in the 13-county Atlanta met-
ropolitan area during the calendar year 2004. Given the equipment and methods used in the Commute
Atlanta vehicle activity data can be linked back to general household demographic parameters (household
income, household size, and vehicle ownership) and vehicle characteristics (vehicle type and model year).
Approximately 80-85% of the vehicles in the study are not shared, meaning that most vehicle activity can
also be linked back to individual driver characteristics (age and gender).
The research team developed weekday and weekend soak and start time distributions and engine starts
per day by demographic and vehicle characteristics parameters, using the same hour of day intervals
and soak time groups employed in the MOBILE6.2 (U.S. EPA, 2001; U.S. EPA, 2003). After devel-
oping the soak and start time distributions and engine starts per day from Commute Atlanta trip data,
the research team conducted MOBILE6.2 emission rate modeling to assess the potential impacts on
the regional emission inventory for the 13-County Atlanta Metropolitan Area, GA. The research team
also examined potential emissions benefits from changing soak and start time distributions by apply-
ing the Commute Atlanta MOBILE6.2 external data files to three other areas, including Gaston County,
NC, Mecklenburg County, NC, and York County, SC. The research team found that the start and soak
distributions observed in Atlanta were significantly different from the default distributions currently
used in the MOBILE6.2 emission rate model, and that the use of the observed Atlanta distributions has
a significant impact upon predicted emission rates and inventories generated using these emission rates.
By applying Commute Atlanta soak and start time distributions and engine starts per day in MOBILE6.2
emission rate modeling, engine start VOC emission rates are predicted to be 17.4% lower and hot soak
VOC emission rates are predicted to be 27.3% lower. These significant reductions can account for an
8.3% reduction in predicted onroad VOC emissions in the 13-county Atlanta metropolitan area.
iii
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FOREWORD
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protect-
ing the Nation's land, air, and water resources. Under a mandate of national environmental laws,
the agency strives to formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and nurture life. To meet this man-
date, EPA's research program is providing data and technical support for solving environmental
problems today and building a science knowledge base necessary to manage our ecological re-
sources wisely, understand how pollutants affect our health, and prevent or reduce environmental
risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the agency's center
for investigation of technological and management approaches for preventing and reducing risks
from pollution that threaten human health and the environment. The focus of the laboratory's
research program is on methods and their cost-effectiveness for prevention and control of pol-
lution to air, land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites, sediments, and ground water; prevention and control
of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with both public and
private sector partners to foster technologies that reduce the cost of compliance and to antici-
pate emerging problems. NRMRL's research provides solutions to environmental problems by:
developing and promoting technologies that protect and improve the environment; advancing
scientific and engineering information to support regulatory and policy decisions; and providing
the technical support and information transfer to ensure implementation of environmental regula-
tions and strategies at the national, state, and community levels.
This publication has been produced as part of the laboratory's strategic long-term re-
search plan. It is published and made available by EPA's Office of Research and Development to
assist the user community and to link researchers with their clients.
Sally Gutierrez, Director
National Risk Management Research Laboratory
IV
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EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental Pro-
tection Agency and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use. This document is available to the
public through the National Technical Information Service, Springfield, Virginia 22161.
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TABLE OF CONTENTS
ABSTRACT iii
FOREWORD iv
EPA REVIEW NOTICE v
TABLE OF FIGURES viii
TABLE OF TABLES ix
TABLE OF ACRONYMS x
Overvi ew 1
Commute Atlanta Data 2
Data Collection and Quality Assurance Process 2
Data Screening 6
Methodology 7
Development of Soak and Start Time Distributions 7
Soak Time Distributions by Vehicle Characteristics 7
Soak Time Distributions by Demographic Parameters 8
Soak Time Distributions by Season 8
Emissions Impact Analysis 8
Demographic Weighting Factors 10
Soak/Start Time Distributions and Engine Starts per Day 11
Soak Time Distributions 11
Soak Time Distributions for Weekday and Weekend 14
Distributions of Soak Time Durations by Day and by Vehicle Characteristics 19
Distributions of Soak Time Durations by Demographic Parameters 21
Soak Time Durations by Season and Vehicle Characteristic 25
Start Time Distributions 27
Engine Starts per Day 31
Impacts on MOBILE6.2 Modeling and Emissions Inventory Development Implications....32
Impacts on MOBILE6.2 Modeling 32
LDV Exhaust Engine Start Emission Rates 33
LDV Evaporative Hot Soak Emission Rates 36
Impacts on Atlanta Mobile Source Emissions Inventory Development 37
vi
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Impact on Emissions Inventory Development in Other Cities 38
Conclusions 41
Appendix A: Commute Atlanta Soak Time Distributions 42
Appendix Al: Commute Atlanta Weekday Soak Time Distributions 43
Appendix A2: Commute Atlanta Weekend Soak Time Distributions 44
Appendix A3: Commute Atlanta Weekday Soak Time Distributions Weighted by
Sample Stratum (Household Size, Household Income, and Vehicle Ownership) 45
Appendix A4: Commute Atlanta Weekend Soak Time Distributions Weighted by
Sample Stratum (Household Size, Household Income, and Vehicle Ownership) 46
Appendix B: Commute Atlanta Engine Start Time Distributions 47
Appendix C: MOBILE6.2 Control Files 48
Appendix Cl: Mobile6.2 Control File for the 13-County Atlanta
Metropolitan Area, GA 49
Appendix C2: Mobile6.2 Control File for Gaston County, NC 50
Appendix C3: Mobile6.2 Control File for Mecklenburg County, NC 51
Appendix C4: Mobile6.2 Control File for York County, SC 52
References 53
vn
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TABLE OF FIGURES
Figure 1: Configuration of the Georgia Tech Trip Data Collector 2
Figure 2: 2004 Commute Atlanta Soak Time Distributions 12
Figure 3: Soak Time Distributions by Day of Week 13
Figure 4: Soak Time Distributions for Time of Day 14
FigureS: MOBILE6.2 Default Weekday Soak Time Distribution 16
Figure 6: MOBILE6.2 Default Weekend Soak Time Distribution 16
Figure 7: Commute Atlanta Weekday Soak Time Distribution 17
Figure 8: Commute Atlanta Weekend Soak Time Distribution 17
Figure 9: Commute Atlanta Weekday Soak Time Distribution (Weighted) 18
Figure 10: Commute Atlanta Weekend Soak Time Distribution (Weighted) 18
Figure 11: Average Soak Time Duration (Seconds) by Day of Week, by Vehicle Model Year
Group 19
Figure 12: Average Soak Time (Seconds) by Day of Week, by Vehicle Type 20
Figure 13: Average Soak Time Duration (Seconds) by Day of Week for LDVs and for Three
LOT Types 21
Figure 14: Average Soak Time Duration (Seconds) by Household Size 22
Figure 15: Average Soak Time Duration (Seconds) by Household Income Group 23
Figure 16: Average Soak Time Duration (Seconds) by Vehicle Ownership 24
Figure 17: Average Soak Time Duration (Seconds) by Driver Age Group 24
Figure 18: Average Soak Time Duration (Seconds) by Driver Gender 25
Figure 19: Average Soak Time Duration (Seconds) by Season, by Model Year Group 26
Figure 20: Average Soak Time Duration (Seconds) by Season, by Vehicle Type 27
Figure 21: Weekday Engine Start Time Distributions for Commute Atlanta LDVs, Commute
Atlanta LDTs, and the MOBILE6.2 Default LDV/LDT Distribution 28
Figure 22: Weekend Engine Start Time Distributions for Commute Atlanta LDVs, Commute
Atlanta LDTs, and the MOBILE6.2 Default LDV/LDT Distribution 29
Figure 23: Demographic-Parameter-Weighted Weekday Start Time Distributions for Commute
Atlanta LDV, Commute Atlanta LOT, and MOBILE6.2 LDV/LDT 30
Figure 24: Demographic-Parameter-Weighted Weekend Engine Start Time Distributions for
Commute Atlanta LDV, Commute Atlanta LOT, and MOBILE6.2 LDV/LDT 30
Figure 25: LDV Exhaust Engine Start Emission Rates for each Modeling Scenario 35
Figure 26: LDV Evaporative Hot Soak Emission Rates for each Modeling Scenario 37
Vlll
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TABLE OF TABLES
Table 1: Vehicle Trips Collected in the Year 2004, Excluded by the QA/QC process, and Used
for Soak and Start Time Analysis 6
Table 2: Vehicle Technology/Model Year Groups 7
Table 3: MOBILE6.2 Modeling Scenarios for Emissions Impact Analysis 9
Table 4: Weighting Factors for each Sampling Stratum used in Calculating the Relative
Contribution of each Stratum to Regional Average Distributions 11
Table 5: Weekday and Weekend Engine Starts per Day for LDVs and LDTs 32
Table 6: Commute Atlanta LDV Exhaust Engine Start Emission Rate Changes Relative to
MOBILE6.2 Default Data 35
Table 7: Demographic-Parameter-Weighted LDV Exhaust Engine Start Emission Rate Changes
from Commute Atlanta Data 36
Table 9: Ratios of Start and Hot Soak Emission Rates for Gaston County, NC, Mecklenburg
County, NC, and York County, SC (Using MOBILE6.2 Default Data) to the Emission
Rates for the Atlanta Metropolitan Area (Using Commute Atlanta Data) 39
Table 10: Ratios of Start and Hot Soak Emission Rates for Gaston County, NC, Mecklenburg
County, NC, and York County, SC (Using Commute Atlanta Data) to the Emission
Rates for the Atlanta Metropolitan Area (Using Commute Atlanta Data) 40
Table 11: MOBILE6.2 Control Parameters Affecting Start and Hot Soak Emission Rates 40
IX
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TABLE OF ACRONYMS
ATL unweighted Commute Atlanta data
CPU central processing unit
GDNR Georgia Department of Natural Resources
GPRS/GSM General Packet Radio Service/ Global Systems for Mobile Communications
GPS global positioning system
GT-TDC Georgia Tech-Trip Data Collector
I/M inspection/maintenance
LOT light duty truck
LDT1 light duty truck 1
LDT2 light duty truck 2
LDT3 light duty truck 3
LDT4 light duty truck 4
LDV light duty vehicle
MARTA Metropolitan Atlanta Rapid Transit Authority
Min/Max minimum/maximum
MySQL open-source database
NC North Carolina
OBD on-board diagnostic
QA/QC quality assurance/quality control
RVP Reid Vapor Pressure
SC South Carolina
SIP state implementation plan
SiRFstarll a global positioning system chipset technology
SMS short message service
SUVs sport utility vehicles
TDMA time division multiple access
U.S. EPA U.S. Environmental Protection Agency
VOC volatile organic compounds
WATL weighted Commute Atlanta data
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Overview
The Georgia Institute of Technology (Georgia Tech) School of Civil and Environmental
Engineering research team analyzed the 2004 second-by-second vehicle activity data obtained
from vehicles in the Atlanta Commuter Choice Value Pricing Initiative, otherwise known as
Commute Atlanta. The onboard monitoring equipment installed in each participating Commute
Atlanta vehicle records each second of vehicle activity. Hence, each engine event (engine on,
engine off) is time-stamped to provide the start and end times of each vehicle trip. The times of
each trip end can be used to directly quantify the number of engine starts per day, the start times
for each trip, and the durations of soak times between trips. (The soak time affects exhaust start
and exhaust running emissions. A vehicle is considered to be soaking if its engine is not run-
ning. Soak time is the length of time between the engine turn off time and engine start time. Cold
soak time in MOBILE6 determines the percentage of vehicles that have been soaking for a given
amount of time prior to an engine start, for each hour of the day. The hot soak time distributions
represent the proportion of vehicles experiencing a hot soak of a given duration at each hour of
the day.) For the purposes of the analyses presented in this report, the research team followed
the same criteria U.S. Environmental Protection Agency (EPA) used to develop soak and start
time distributions and engine starts per day in the MOBILE6.2 emission rate model (U.S. EPA,
2001; U.S. EPA, 2003).
The objective of research efforts reported herein is to develop gasoline vehicle soak and
start time distributions and engine starts per day for EPA light-duty vehicle (LDV) and light-duty
truck (LDT combining LDT1, LDT2, LDT3, and LDT4) classes using vehicle trip data collected
in the 13-county Atlanta metropolitan area during the calendar year 2004. Given the equipment
and methods used in the Commute Atlanta vehicle activity data can be linked back to general
household demographic parameters (household income, household size, and vehicle ownership)
and vehicle characteristics (vehicle type and model year). Approximately 80-85% of the vehicles
in the study are not shared, meaning that most vehicle activity can also be linked back to indi-
vidual driver characteristics (age and gender).
The research team developed weekday and weekend soak and start time distributions and
engine starts per day by demographic and vehicle characteristics parameters, using the same hour
of day intervals and soak time groups employed in the MOBILE6.2 (U.S. EPA, 2001; U.S. EPA,
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2003). After developing the soak and start time distributions and engine starts per day from
Commute Atlanta trip data, the research team conducted MOBILE6.2 emission rate modeling to
assess the potential impacts on the regional emission inventory for the 13-County Atlanta Metro-
politan Area, GA. The research team also examined potential emissions benefits by applying the
Commute Atlanta MOBILE6.2 external data files to three other areas, including Gaston County,
NC, Mecklenburg County, NC, and York County, SC. The research team found that the start and
soak distributions observed in Atlanta were significantly different from the default distributions
currently used in the MOBILE6.2 emission rate model, and that the use of the observed Atlanta
distributions has a significant impact upon predicted emission rates and inventories generated us-
ing these emission rates.
Commute Atlanta Data
The Georgia Tech research team has been collecting and managing second-by-second
vehicle activity data from a fleet of private vehicles monitored in Atlanta since 2003. More than
270 households and 470 vehicles participated in the Phase I (2003 to 2005) data collection effort.
To date, the monitoring program has tracked more than 1.3 million vehicle trips on a second-
by-second basis. The research team selected vehicle trip data collected during the calendar year
2004 (1/1/2004 to 12/31/2004) for this research effort (614,276 vehicle trips).
Data Collection and Quality Assurance Process
Georgia Tech Trip Data
Collectors (GT-TDC) used in the
Commute Atlanta study are Linux-
based 386 computers that include a
CPU, power system, compact flash
memory, GPS, cellular transceiver,
and input/output lines (Figure 1).
Figure 1: Configuration of the Georgia Tech Trip Data Collector
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Optional connections include six on/off sensors (which can be used to monitor seat belts
or brake lights) and two serial connections [one of which is used to monitor onboard diagnostic,
(OBD), data]. The GT-TDC is connected to constant battery power as well as switched power
(vehicle ignition). Hence, no human interaction is required for vehicle turn-on/off. These fea-
tures make data collectors a practical option to monitor vehicle activities 24 hours per day over
an extended period. Trip data recorded by the GT-TDC are wirelessly transferred through the
digital cellular communication network. A digital cellular transceiver is capable of sending data
through low cost short message service (SMS) or sending larger volume circuit switched data
- time division multiple access (TDMA). The newest systems currently being deployed in 150
Atlanta vehicles are equipped with General Packet Radio Service/Global Systems for Mobile
Communications (GPRS/GSM) cellular modules, providing the capability of real-time, interac-
tive vehicle position monitoring.
The switched power connection to the GT-TDC triggers the data recording process each
time the engine starts. The GT-TDC records each second of vehicle activity data to the com-
pact flash memory in an encrypted form. Second-by-second data elements include: date, time,
vehicle position (latitude and longitude), vehicle speed (phase differential speed calculated by the
SiRFstarll GPS unit), and engine operating parameters (monitored for approximately 40% of the
vehicles). When the driver turns off the engine, the GT-TDC writes a trip record summary and
enters a sleep mode. Approximately once per week, the research team polls the unit and trig-
gers a data upload to the main server system. The encrypted data pass to the server via cellular
connection, where programs automatically decrypt and process data into storage arrays. A series
of programs process each trip to route and summarize trip characteristics. For example, total trip
time equals the trip record length (one-second per record). The trip distance calculation methods
are proprietary, but they include a Kalman filter for vehicle speed, and shortest path infill dis-
tance from trip origin position (equal to destination of previous trip) to the point where the first
viable satellite data point is collected.
A series of quality assurance/quality control (QA/QC) checks are performed for every trip
to identify potential data integrity problems. These methods are outlined below:
• An automated system monitors the operating status of equipment and verifies garage
location. By automating box reporting status commands and storing the results in a
master MySQL table, the researchers can identify systems that need to be replaced
and households that may have changed location. Automated e-mail messages alert the
team to potential problems so that repairs can be scheduled, significantly decreasing
equipment downtime. The team uses these data to determine when a unit has failed
and to differentiate vehicle inactivity from failure to report trips. The automated sys-
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terns cannot identify when a vehicle owner has temporarily disconnected a unit from
the power source and then later reconnected that unit. Given the relative inaccessibil-
ity of the hardware, this is not likely to be a significant issue. The next generation
equipment will automatically detect and report a power system disconnect.
Data integrity checks and data consistency checks were undertaken when populating
the MySQL database to ensure that the correct households, vehicles, and individuals
are joined in applicable tables. This process included both an automated and visual
check. In early 2006, the team manually audited all equipment install and uninstall
paperwork and verified the database entries for each household and vehicle.
The team developed a graphical user interface to help researchers interact with the
MySQL database. Customized functions for updating the database use data entry
forms to update multiple tables automatically. These features allow users to respond
more readily to frequently occurring scenarios (e.g., sale of a vehicle, opt-out of a
household). This helps maintain database integrity, improves data entry efficiency,
and reduces the likelihood of data entry error.
The research team has automated the comparison of trip summaries and processed
trips, reported on separate communication channels (proprietary process). Using this
technique, the team identified 11,087 trip files that appeared to have been generated by
the data collection devices, but not processed by the server. More than 6,209 (56%)
of the total missing files were not trips, but were files created every few seconds by
corrupted onboard software aboard five vehicles. The remaining 4,878 (44%) missing
trip files were distributed among 462 boxes (an average of approximately 10 trips/ve-
hicle over an 18-month period). These files were either lost during data transmission,
or overwritten by newer trip files when the vehicle communication system failed. The
4,874 dropped trips do not constitute a significant fraction (0.4%) of the total 1.2 mil-
lion trips (from August 2003 to September 2005) and many of these trips are likely to
have been zero mile trips based upon analysis of the size of the missing file. The data
transfer issue causing these drops will be eliminated in the next generation of equip-
ment when transmitted using a newer cellular technology (GPRS/GSM cellular mod-
ules).
The research team also conducts a final visual review of all data. Using a database
analysis coupled with a visual review of plotted data for confirmation purposes, the
team determined that trip data were missing for 18 vehicles from November 24, 2004
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through January 14, 2005. The loss occurred during the period of service disruption
on the part of the cellular provider. We have re-coded the data for these vehicles, as if
each unit failed on November 24 and was replaced on January 14. Thus, the zero-trip
data from these 18 vehicles during this date range are excluded from the database from
start and soak analyses.
• During September and October 2005, the research team performed an additional
QA/QC pass through all vehicle-trip data to identify and correct any GPS time stamp-
errors. A small fraction of units exhibited these errors due to an internal clock failure.
Such errors are readily identified in the start and soak time distributions by examin-
ing outliers, identifying trip time overlaps (two trips occurring within the same time
interval), and identifying negative soak time increments. A new automated software
feature identifies time stamp problems associated with GPS clock failure, excludes the
data from analysis (trip data and monitored days are excluded, just as if the vehicle
had left the program for that period), and flags the data for human follow-up.
The research team assembled all trip data collected in calendar year 2004. As described
in the QA/QC procedures above, not every trip from every vehicle is available for analysis, due
to potential equipment outages. For daily activity distributions, zero trip days are differentiated
from days in which no data were collected. Hence, a zero value for trips per day is included in
the database only when the research team has determined that the equipment was functional on
that day.
During the initial stages of the travel variability analysis, the research team discovered
that vehicles used part time for commercial purposes have a significant impact on household
travel variability as well as total sample variability. Some of these vehicles make 10 to 20 trips
per weekday - significantly more trips than the typical household. Vehicles identified by their
owners as being used part time for business purposes made approximately 5% of the total ve-
hicle trips. The effect was so significant that the research team now excludes these vehicles from
vehicle activity analyses and excludes these households from household activity analyses. The
team has determined that such vehicles and households need to be sampled and analyzed sepa-
rately from other households in the region. In addition, vehicle trips made by diesel vehicles,
Metropolitan Atlanta Rapid Transit Authority (MARTA) buses and Georgia Tech vans are ex-
cluded from the start and soak distribution analysis.
The start and soak time analyses in this report include all vehicle activity monitored in
2004. The research team has developed a series of routines to identify the intra-regional and
inter-regional status for each trip in the 2004 database. Approximately 7.4% of all trips recorded
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in 2004 begin or end outside of the 13-county Atlanta metropolitan area. These trips are coded
as extra-regional trips. The researchers are currently conducting analyses to compare the start
and soak distributions for long-distance tours (travel departing the region, traveling outside of the
region, and then returning to the region) and the purely intra-regional travel. The research team
will prepare a separate manuscript for journal publication once the findings are complete.
Data Screening
The research team processed all trip data collected in the calendar year 2004 with each
step of the data QA/QC process and used only the data that passed the QA/QC procedures for
soak and start time distributions and engine start per day. During calendar year 2004, the re-
search team monitored a total of 667,836 vehicle trips. From the collected total vehicle trips,
the research team excluded vehicle trips generated by buses, Georgia Tech service vans, diesel
vehicles, and commercial vehicles. The research team excluded trips generated from the small
number of trip data collectors that had data recording problems, such as recording wrong starting
or ending trip time, global positioning system (GPS) failures, etc. Recording problems that cause
negative and zero soak intervals, zero travel duration, extremely long trip duration (greater than
a 5-hour travel duration), high average speed [such as an average speed of 180 miles per hour
(mph)], or combination of them have been excluded. In addition, the first trip of the year from
each trip data collector was excluded because soak duration for the first trip cannot be calculated.
After excluding these trips, the research team used 614,276 trips for soak and start time analysis.
Table 1 shows the vehicle trips collected in the year 2004, excluded by the QA/QC process, and
the data used in the start and soak analyses.
Table 1: Vehicle Trips Collected in the Year 2004, Excluded by the QA/QC process, and Used
for Soak and Start Time Analysis.
Vehicle Trips Vehicle Trips
Collected in the calendar year 2004
Excluded by the
QA/QC process
Buses, Georgia Tech Vans, and Commer-
cial Use Vehicles
Minus and Zero Soak Time Vehicle Trips
Zero Duration Trips
Greater than 5-hour Duration Trips
High Average Speed Trips
First Vehicle Trips of the Year
Used for Soak and Start Time Analysis
667,836
52,227
402
269
102
4
556
614,276
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Methodology
Development of Soak and Start Time Distributions
The research team developed weekday and weekend soak and start time distributions
using the MOBILE6.2 soak time and hour intervals (U.S. EPA, 2001; U.S. EPA, 2003). All soak
and start time distributions developed by the research team are directly comparable to weekday
and weekend soak and start time distributions used in MOBILE6.2. The research team included
the 2004 vehicle trip data and did not drop any vehicle trips once the data passed the QA/QC
process. In these analyses, even a three-second vehicle trip is considered a unique vehicle trip.
In addition, soak duration is assigned to engine start time because that is when start related emis-
sions begin (i.e., g/mile and g/start). The Sunday to Monday soak is assigned to Monday. The
Monday morning to afternoon soak is assigned to afternoon.
Soak Time Distributions by Vehicle Characteristics
In this research, the research team considered two vehicle types and four vehicle technol-
ogy/model year groups. The two vehicle types included passenger cars (LDV) and light-duty
trucks (LOT). Vehicle technology/model year groups included pre-1994, 1994-1995, 1996-1999,
and post-1999. These vehicle technology/model year groups were derived from light-duty gaso-
line vehicle certification standards and vehicle technology development. Table 2 shows vehicle
technology/model year groups.
Table 2: Vehicle Technology/Model Year Groups
Vehicle Age Groups Criterion
Pre-1994
1994 to 1995
1996 to 1999
Post- 1999
TierO
Tier 1
Tier 1, phase-in of vehicles with enhanced evaporative controls
Tier 1, addition of supplemental federal test procedure
The research team created soak time distributions across the combinations of four tech-
nology/model year groups, two vehicle types, for weekdays and weekends.
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Soak Time Distributions by Demographic Parameters
The research team developed separate soak time distributions across five different de-
mographic parameters: household income, household size, vehicle ownership, driver age, and
driver gender (Guensler et al., 2004). Household income employed four clusters: $0-$30,000,
$30,000 to $75,000, $75,000 to $100,000, and more than $100,000). Household size and vehicle
ownership parameters were each divided into three groups: 1, 2, and 3+. Driver age groups
were binned (grouped) by: 16-24, 25-34, 35-44, 45-54, 55-64, and 65+.
Households in the Commute Atlanta study were recruited in eight sampling strata, defined
by household income, household size, and vehicle ownership (Ogle et al., 2005). The research
team developed start and soak distributions for each of these sampling strata. Because equal
numbers of households are not present in each sampling strata, and because each sampling strata
represents a different fraction of regional households, the team developed weighting factors for
the eight Commute Atlanta sampling strata so that regional distributions could be developed from
the eight individual distributions. That is, to account for Commute Atlanta sample size effects
(potential over- or under-sampling by demographic strata), weighting factors are applied to soak
and start time distributions to develop weighted soak and start time distributions (see the section
entitled "Demographic Weighting Factors").
Soak Time Distributions by Season
For soak time distributions by season, the research team separated vehicle trips into four
seasons: winter (December to February), spring (March to May), summer (June to August), and
fall (September to November). Soak time distributions were developed by vehicle type and tech-
nology/model year group for each season.
Emissions Impact Analysis
For the emissions impact analyses, the research team developed fifteen MOBILE6.2
modeling scenarios. The fifteen MOBILE6.2 modeling scenarios employ combinations of
MOBILE6.2 default data, Commute Atlanta data, and Commute Atlanta data weighted by de-
mographic parameters for the soak time distribution, start time distribution, and engine starts
per day inputs. Table 3 shows the fifteen MOBILE6.2 modeling scenarios that result from the
combinations of the input data files.
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Table 3: MOBILE6.2 Modeling Scenarios for Emissions Impact Analysis
Scenarios Emissions Rate Modeling Data
1
2
3
4
5
6
7
8
8
9
10
11
12
13
14
15
Soak Time Distribution
EPA1
ATL2
EPA
EPA
ATL
ATL
EPA
ATL
ATL
ATL
ATL
WATL3
ATL
WATL
WATL
WATL
Start Time Distribution
EPA
EPA
ATL
EPA
ATL
EPA
ATL
ATL
ATL
ATL
WATL
ATL
WATL
ATL
WATL
WATL
Files
Engine Starts per Day
EPA
EPA
EPA
ATL
EPA
ATL
ATL
ATL
ATL
WATL
ATL
ATL
WATL
WATL
ATL
WATL
^EPA: MOBILE6.2 default soak and start time distributions and engine starts per day
2) ATL: Commute Atlanta soak and start time distributions and engine starts per day
3) WATL: Weighted Commute Atlanta soak and start time distributions and engine starts per day
The research team conducted MOBILE6.2 emission rate modeling for each scenario
using modeling control file developed for the Atlanta 13-county 1-hr ozone nonattainment area
(GDNR, 2005). As examples of emissions impact analysis, the research team compared volatile
hydrocarbon compounds (VOC) emissions rates across the scenarios.
The research team performed emissions impact analysis in regional or local emissions
inventory development with MOBILE6.2 modeling control files for the 13-county Atlanta met-
ropolitan area and three other regions (Gaston County, NC, Mecklenburg County, NC, and York
County, SC). U.S. EPA staff provided modeling control files for these three other regions. This
analysis provides not only emissions impact in Atlanta regional emissions inventory develop-
ment, but also provides insights as to the potential effect in other regions, where different envi-
ronmental parameters, inspection and maintenance (I/M) programs, fuels programs, registration
distributions, etc., may exist.
-------
Demographic Weighting Factors
In transportation planning and modeling, patterns of vehicle activity are noted across
household income, vehicle ownership, household size, etc. Household demographics and life-
style stage influence tripmaking, which in turn influences start and soak time distributions within
a region. For instance, a large, high-income household owning multiple vehicles will tend to
generate more trips (shorter average soak times) compared to smaller, low-income, single vehicle
households.
The proportion of high-income households participating in the Commute Atlanta project
is greater than actual proportion of high-income households in the 13-county region. The pro-
portion of low-income households is lower than the actual proportion in 13-county region. The
eight demographic strata used for recruitment (household income, vehicle ownership, and house-
hold size groups) represent different fractions of regional households. The research team created
demographic strata weighting factors, based upon the relative contribution of each household
stratum to the overall regional demographic composition. The percentage of households in each
sampling stratum of the 2004 Commute Atlanta household data was compared to the percentage
of 13-county Atlanta metropolitan households in each sampling stratum (derived from 2002 U.S.
Census demographic data). Sampling strata ratios were used to adjust the contribution of each
2004 Commute Atlanta stratum to the metropolitan average. For instance, household portions
of sampling stratum 1 in Table 4 (households with annual income of less than $30,000, owning
one or more vehicles, of any household size) represented 19.85% of the 2002 U.S. Census data
for the 13-county Atlanta metropolitan area, but only 6.29% of the 2004 Commute Atlanta data.
Therefore, the weighting factor for this stratum is 3.1566 (0.1985 divided by 0.0629). Weighting
factors for each stratum are applied to the Commute Atlanta data to estimate the weighted con-
tributions of soak and start time distributions and engine starts per day to the regional average.
Table 4 shows the weighting factors for each sampling stratum.
10
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Table 4: Weighting Factors for each Sampling Stratum used in Calculating the Relative Contri-
bution of each Stratum to Regional Average Distributions
2002 U.S. 2004
Sampling Household Vehicle Household CENSUS Commute Weighting
Stratum Income Ownership Size Atlanta Atlanta Factors
Household Household
1
2
3
4
5
6
7
8
9
<30k
30-75k
30-75k
30-75k
30-75k
75k+
75k- 100k
>100k
UNK
1+
1+
1
2+
2+
1+
1+
1+
Any
Any
1
2+
2
3+
1
2+
2+
Any
0.1985
0.1219
0.0734
0.1143
0.1499
0.0302
0.1305
0.1812
N/A
0.0629
0.0882
0.0380
0.1305
0.1589
0.0116
0.1829
0.3271
N/A
3.1566
1.3818
1.9326
0.8759
0.9437
2.6065
0.7138
0.5541
1.0000
Soak/Start Time Distributions and Engine Starts per Day
The research team prepared soak and start time distributions and engine starts per day
using the 2004 Commute Atlanta trip data passing the QA/QC criteria described earlier in the
"Data Collection and Quality Assurance Process" section.
Soak Time Distributions
The research team created thirteen soaks time intervals to present the general soak time
distribution, with a maximum four day soak time duration. These thirteen soak time intervals
include the sixty-eight soak codes (1 to 68) applied in the EPAMOBILE6.2 emission rate model.
Figure 2 shows the overall soak time distribution. Two peaks are noted, one contributing 16.1%
of soaks in the 0 to 5 minute soak time interval and another contributing 17.9% of all soak dura-
tions in the 8 to 24 hour soak time interval.
11
-------
20.0%-
15.0%-
to
o
CO
™ 10.0%-
o
-------
20.0%-
ZHJ ?~ JU *X 7 •
-------
50.0%-
40.0% -
m
^ 30.0%-
s
(0
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§
fc 20.0%-
Q.
10.0%-
n n%-
Jll
f
1
Tl
[
f
ll
r
If
f
f
f
ARC TIME OF
DAY
• Morning
• Midday
D Afternoon
• Night
SOAK TIME INTERVAL
Figure 4: Soak Time Distributions for Time of Day
Soak Time Distributions for Weekday and Weekend
The research team developed soak time distributions using the sixty-eight MOBILE6.2
soak codes (soak time intervals) for weekdays and weekends. The sixty-eight MOBILE6.2 soak
time intervals include: one category for soak durations less than 1 minute, 29 categories in 1-
minute increment from 1 to 30 minutes, 15 categories in 2-minute increments from 31 to 60 min-
utes, 22 categories in 30-minute increments from 60 to 720 minutes, and one final category for
soak durations greater than 720 minutes. For soak codes 69 ("Restart") and 70 ("Not Used"), the
research team used MOBILE6.2 default values because appropriate values were not generated in
the Commute Atlanta trip data. Appendix Al contains the Commute Atlanta weekday soak time
percentages by hour of day for the 68 MOBILE6.2 soak durations (except soak codes 69 and 70).
Figures 5 and 6 show MOBILE6.2 default weekday and weekend soak time distributions.
MOBILE6.2 default soak time distributions are significantly different from Commute Atlanta
soak time distributions (Figures 7 and 8). The Commute Atlanta distributions are markedly
14
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smoother (likely due to the large data set used to generate the distributions). The mid-day default
distributions for MOBILE6.2 show significantly higher fractions of long and short soaks com-
pared to the Commute Atlanta distributions.
From 3 a.m. to 11 a.m., the Commute Atlanta weekday soak time distributions exhibit
high frequencies (greater than 0.1 for each hour) corresponding to soak time durations longer
than 720 minutes. Three other high frequencies were observed at 7 p.m., 8 p.m., and 11 p.m.
However, high soak time frequencies (greater than 0.1) from MOBILE6.2 weekday soak time
distribution occurred during 6 a.m. to 10 a.m., which was a much narrower time window than the
Commute Atlanta weekday soak time distribution. Appendix Al shows the Commute Atlanta
weekday soak time fractions for each hour of the day for the 68 MOBILE6.2 soak codes.
The Commute Atlanta weekend soak time distribution is similar to the MOBILE6.2
default weekend soak time distribution, but the hour window for high frequencies is different.
The Commute Atlanta weekend soak time distributions show high frequencies (greater than 0.10)
corresponding to soak durations greater than 720 minutes from 4 a.m. to 2 p.m. Whereas, the
MOBILE6.2 default weekend soak time distribution shows high frequencies corresponding to
soak durations greater than 720 minutes from 6 a.m. to 2 p.m. Appendix A2 shows the Commute
Atlanta weekend soak time fractions for each hour of day for the 68 MOBILE6.2 soak codes.
The research team also developed regional soak time distributions weighted by demo-
graphic parameters (with weightings applied to each demographic sampling strata to account
for the fact that the Commute Atlanta household distributions differ from the metropolitan area
demographic distributions). Figures 9 and 10 show the weighted Commute Atlanta weekday and
weekend soak time distributions, respectively. The weighted Commute Atlanta soak time distri-
butions were almost identical to the unweighted distributions. Hence, the demographic weight-
ing process is not necessary for the development of regional soak and start time distributions
with 2004 Commute Atlanta trip data. Appendices A3 and A4 show the demographic-parameter-
weighted Commute Atlanta weekday and weekend soak time fractions for each hour of day for
68 MOBILE6.2 soak codes, respectively.
The Commute Atlanta weekday and weekend soak time distributions can be substituted
for MOBILE6.2 default weekday and weekend soak time distributions in emission rate model-
ing for use in Atlanta metropolitan area regional emissions inventory development. The section
entitled "Impacts on MOBILE6.2 Modeling and Implications on Emissions Inventory Develop-
ment" explores the impacts on emission rates and regional emissions inventories when Commute
Atlanta soak time distributions replace the MOBILE6.2 default distributions in the modeling
runs.
15
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Frequency Bins
' • 0.40-0.50
DO.30-0.40
0 0.20-0.30
• 0.10-0.20
DO.00-0.10
15
22
29
Soak Time (minutes)
12
15
18
630
Hour of Day 21
Figure 5: MOBILE6.2 Default Weekday Soak Time Distribution
Frequency Bins
• 0.40-0.50
D 0.30-0.40
D 0.20-0.30
• 0.10-0.20
O 0.00-0.10
15
Soak Time (minutes)
12 ,
15
18
Hour of Day 21
420
630
Figure 6: MOBILE6.2 Default Weekend Soak Time Distribution
16
-------
Frequency Bins
• 0.40-0.50
D 0.30-0.40
D 0,20-0,30
• 0.10-0.20
DO.00-0.10
Soak Time (minutes)
18
630
Hour of Day 21
Figure 7: Commute Atlanta Weekday Soak Time Distribution
0.5
Frequency Bins
• 0.40-0.50
DO.30-0.40
D 0.20-0.30
• 0.10-0.20
DO.00-0.10
210
Soak Time (minutes)
420
Hour of Day
630
Figure 8: Commute Atlanta Weekend Soak Time Distribution
17
-------
Frequency Bins
• 0,40-0.50
DO. 30-0.40
D 0.20-0.30
• 0.10-0.20
no.oo-o.io
15
Time (minutes)
12
15
18
21
Hour of Day
Figure 9: Commute Atlanta Weekday Soak Time Distribution (Weighted)
0.5
Frequency Bins
• 0.40-0.50
D 0.30-0.40
D 0.20-0.30
• 0.10-0.20
DO.00-0.10
Soak Time (minutes)
12
15
18
Hour of Day 21
630
Figure 10: Commute Atlanta Weekend Soak Time Distribution (Weighted)
18
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Distributions of Soak Time Durations by Day and by Vehicle Characteristics
Distributions of soak time durations (in seconds) by day of week were developed for
vehicle characteristics, including vehicle model year/technology group and vehicle type. Vehicle
model year/technology groups are grouped by model year: pre-1994, 1994-1995, 1996-1999,
and post-1999. Younger vehicles exhibit shorter soak time durations (more frequent use), and
soak time durations generally decreased from Sunday through weekdays to Saturday. Soak time
durations for all vehicle model year groups were the longest on Monday and shortest on Saturday
(more vehicle inactivity occurs on Saturdays and Sundays, leading to the longer soak time for
starts on Sundays and Mondays). Newer vehicles appear to be driven more on the weekends, as
evidenced by shorter soak times, indicating that newer vehicles may be preferred when multiple
vehicles are available. Older vehicles (pre-1994 and 1994-1999 groups) tend to have longer soak
times than the newer vehicle groups. However, it is important to keep in mind that this study
only instrumented vehicles that owners report are used more than 3,000 miles per year. Hence,
the mean and confi-
dence bounds for the
oldest vehicle set may
be representative for
active vehicles, but is
probably not repre-
sentative for the older
inactive vehicles
present in the region-
al vehicle registration
database. Figure 11
shows the distribu-
tions of soak time
durations by day of
week for each vehicle
model year group.
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Soak time distributions (in seconds) by day of week were developed for automobiles,
vans, sport utility vehicles (SUVs), and pickup trucks. In general, soak time duration decreased
from Sunday through the weekdays for both LDV and LDT. However, soak time durations for
LDVs (automobiles) were generally longer than soak time durations for LDTs (vans, SUVs, and
pickups), especially on Sundays and Mondays. This indicates more frequent LDT use on week-
ends. Figure 12 shows the distributions of soak time durations by day of week for LDVs and
LDTs. Within the LDT category, the average soak time duration for pickup trucks was much
longer on Sunday and Monday (indicating less weekend activity). The soak time durations for
vans and SUVs were significantly shorter on Sundays and Mondays (indicating more weekend
activity). The van and SUV effect dominates the LDT difference. Figure 13 shows the average
soak time durations by day for LDVs and the three LDT types.
26000-
24000-
UJ 22000-
£
p
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O 20000-
35
0
0> 18000-
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{,
id) T
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VEHICLE TYPE
I CAR
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\ ^
MOBILE6.2 DAY OF WEEK
Figure 12: Average Soak Time (Seconds) by Day of Week, by Vehicle Type
20
-------
30000-
25000-
111
O 20000-
09
0
i
15000-
10000-
0 <»
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VEHICLE TYPE
I CAR
I VAN
SUV
I PICKUP
\ \ \ \ \ \ \
MOBILE6.2 DAY OF WEEK
Figure 13: Average Soak Time Duration (Seconds) by Day of Week for LDVs and for Three
LDT Types
Distributions of Soak Time Durations by Demographic Parameters
Average soak time durations (seconds) were developed across five demographic pa-
rameters including household size, household income, vehicle ownership, drive age, and driver
gender.
Mean soak time durations for household sizes 1 and 2 were not significantly different,
although the variance for household size 1 was slightly larger than for household size 2. Soak
time duration for the 3+ household size group was significantly shorter than soak time durations
for household sizes 1 and 2. Figure 14 shows the average soak time duration by household size.
Average soak time durations (seconds) were developed for the four household income
groups (less than $30,000, $30,000 to $75,000, $75,000 to $100,000, and more than $100,000).
Average soak time duration for the lowest income group (less than $30,000) was much longer
than was noted for other household income groups, indicating lower tripmaking rates in the low-
21
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est income group). Average soak time duration for the $30,000 to $75,000 income group was the
shortest. Except for the lowest income group, average soak time increases with income (higher
income households tend to own more vehicles, which could reduce tripmaking per vehicle, but
also tend to make even more trips per vehicle). Figure 15 shows average soak time durations by
household income group.
Average soak time durations were all significantly different for 1, 2, and 3+ vehicle
households. As household vehicle ownership increased, average soak time durations significant-
ly increased. Figure 16 shows average soak time duration by vehicle ownership.
Average soak time durations (seconds) varied by driver age. Driver age groups 35 to 44
and 45 to 54 had the shortest soak time durations (i.e., they are more active with respect to mak-
ing vehicle trips), while driver age groups 55 to 64 and 65+ had the longest soak time durations.
Figure 17 shows the distributions of soak time durations by driver age group.
Distributions of soak time durations were significantly different across male and female
drivers. The average soak time duration for male drivers was significantly longer than for female
drivers. Figure 18 shows the distributions of soak time durations by driver gender.
20500 -
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s
p
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18000-
17500-
17000-
16500-
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1 2 >=3
HOUSEHOLD SIZE (Number of Persons)
Figure 14: Average Soak Time Duration (Seconds) by Household Size
22
-------
24000-
23000-
22000-
UJ
21000-
20000-
19000-
18000-
17000-
I
I I I
OO.OOO 30,000- 75,000- >=100,000 Unknown
74,999 99.999
HOUSEHOLD INCOME (Dollars)
Figure 15: Average Soak Time Duration (Seconds) by Household Income Group
23
-------
19000-
LU
2 18500-
O
V)
O
18000-
O)
17500-
1 2 >=3
VEHICLE OWNERSHIP (Number of Vehicles)
Figure 16: Average Soak Time Duration (Seconds) by Vehicle Ownership
21000-
20000-
UJ
19000-
O
CO
o
18000-
s
17000-
1GOOO-
I
I
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<25 25 ~ 34 35 - 44 45 - 54 55 - 64 >« 65 Unknown
DRIVER AGE
Figure 17: Average Soak Time Duration (Seconds) by Driver Age Group
24
-------
1BSOO-
1 swo-
.
O 1ESOO-
H
O
in
en
13000-
17500-
Male Female
DRIVER GENDER
Figure 18: Average Soak Time Duration (Seconds) by Driver Gender
Soak Time Durations by Season and Vehicle Characteristic
Average soak time duration (seconds) by season differ significantly across vehicle model
year/technology group and by vehicle type. The soak time durations in spring were the shortest
of the four seasons, while soak time durations in winter were the longest. Soak time durations in
summer varied across vehicle model year/technology groups more than any other season of the
year. Average soak time durations for pre-1994 vehicles were longer than soak time durations
for post-1996 vehicles. In general, younger vehicles exhibit shorter soak time durations (due
to more frequent vehicle use). Figure 19 shows the average soak time durations by season for
vehicle model year (i.e., technology) groups.
25
-------
23000-
22000-
21000-
1 1 1
LU
H
^ 20000-
1
O 19000-
g
o>
18000-
17000-
16000-
0
0 0
, IT"
'1
» ' » '
1 1 1 1
Spring Summer Fall Winter
VEHICLE MODEL
YEAR
I Pre-1994
I 1994-1995
1996- 1999
I Post-1999
SEASON OF YEAR
Figure 19: Average Soak Time Duration (Seconds) by Season, by Model Year Group
26
-------
20500-
20000-
19500-
UJ
19000-
O 18500-
09
18000-
17500-
17000-
16500-
O
VEHICLE TYPE
I CAR
I TRUCK
Spring Summer Fall Winter
SEASON OF YEAR
Figure 20: Average Soak Time Duration (Seconds) by Season, by Vehicle Type
Start Time Distributions
The research team developed weekday and weekend start time distributions from the
Commute Atlanta vehicle trip data using the same start hour of day intervals as MOBILE6.2
(U.S. EPA, 2001; U.S. EPA, 2003). The Commute Atlanta weekday start time distribution exhib-
its three peaks (morning, noon, and late afternoon), which are similar to the MOBILE6.2 default
start time distributions. However, the magnitudes of the engine start peaks and the time that each
peak occurs in the Commute Atlanta start time distribution are significantly different than those
observed in the MOBILE6.2 default distributions. The morning high peak occurred at 7 a.m. in
the Commute Atlanta distribution, while the morning high peak occurred at 8 a.m. in the MOBI-
ILE6.2 distribution. The noon high peaks occur in the same hours. However, the magnitude in
the MOBILE6.2 distribution was greater than that observed in the Commute Atlanta distribution.
In the evening, the high peak of MOBILE6.2 start time distribution for LDVs and LDTs occurred
at 3 p.m., while the high peak of Commute Atlanta start time distribution occurred at 4 p.m. for
27
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LDVs and 5 p.m. for LDTs. Each of these peaks was also significantly lower in magnitude in the
Commute Atlanta distributions. In the MOBILE6.2 default start time distribution, engine start
fractions sharply decreased from 6 p.m. to 7 p.m. and were essentially flat from 7 p.m. to 5 a.m.
However, Commute Atlanta engine start time fractions gradually decreased from 6 p.m. to 2 a.m.
and then increased from 2 a.m. to 6 a.m. Figure 21 shows weekday start time distributions for
Commute Atlanta LDV, Commute Atlanta LOT and MOBILE6.2 LDV/LDT.
Soak time durations for LDVs and LDTs differed significantly by season. In general, the
soak time distributions and average soak durations for were similar in summer and fall. How-
ever, the distributions and average soak durations were quite different in winter and spring. Soak
time durations for LDVs were shorter than the soak time durations for LDTs in both winter and
spring. Figure 20 shows the average soak time durations by season, by vehicle type.
0.11
0.10
0.09
0.08
0.07
£ 0.06
re
« 0.05
0.04
UJ
0.03
0.02
0.01
0.00
Atlanta LDV
Atlanta LOT
MOBILE6.2
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5
Hour of the day
Figure 21: Weekday Engine Start Time Distributions for Commute Atlanta LDVs, Commute
Atlanta LDTs, and the MOBILE6.2 Default LDV/LDT Distribution
On weekends, start time distributions for MOBILE6.2 defaults and Commute Atlanta data
expressed similar patterns, but their high peaks were slightly different. The MOBILE6.2 default
start time distribution had three high peaks at noon, 2 p.m., and 4 p.m., while Commute Atlanta
start time distributions had one high peak at noon. In the MOBILE6.2 default start time distribu-
28
-------
•Atlanta LDV
Atlanta LOT
-MOBILE6.2
tion, engine start fractions sharply decreased from 6 p.m. to 7 p.m. and were essentially flat from
7 p.m. to 5 a.m. However, Commute Atlanta start time fractions gradually decreased from 6 p.m.
to 2 a.m. and then increased again at 4 a.m. Figure 22 shows weekend engine start time distribu-
tions for Commute Atlanta LDV, Commute Atlanta LOT and MOBILE6.2 default LDV/LDT.
0.11
0.10
0.09
0.08
£ 0.07
u
ss
£ 0.06
5
« 0.05
0)
c
'5> 0.04
111
0.03
0.02
0.01
0.00
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1
Hour of the day
2345
Figure 22: Weekend Engine Start Time Distributions for Commute Atlanta LDVs, Commute
Atlanta LDTs, and the MOBILE6.2 Default LDV/LDT Distribution
The research team also developed demographic-parameter-weighted start time distribu-
tions for LDV and LDT as described in the section entitled "Demographic Weighting Factors".
The weighted Commute Atlanta weekday and weekend start time distributions (Figures 21 and
22) were almost identical to the unweighted Commute Atlanta start time distributions (see Fig-
ures 23 and 24). Appendix B presents weekday and weekend Commute Atlanta start time frac-
tions both unweighted and weighted by demographic parameters.
29
-------
0.11
0.10
0.09
0.08
0.07
0.06
3
0.05
o>
ra 0.04
c
III
0.03
0.02
0.01
0.00
Atlanta LDV
Atlanta LOT
MOBILE6.2
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5
Hour of the day
Figure 23: Demographic-Parameter-Weighted Weekday Start Time Distributions for Commute
Atlanta LDV, Commute Atlanta LOT, and MOBILE6.2 LDV/LDT
0.11
0.10
0.09
0.08
c
O
'•g °-07
5
£ 0.06
g
« 0.05
o> 0.04
LU
0.03
0.02
0.01
0.00
Atlanta LDV
Atlanta LOT
MOBILE6.2
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5
Hour of the day
Figure 24: Demographic-Parameter-Weighted Weekend Engine Start Time Distributions for
Commute Atlanta LDV, Commute Atlanta LOT, and MOBILE6.2 LDV/LDT
30
-------
The Commute Atlanta weekday and weekend start time distributions can be readily sub-
stituted for MOBILE6.2 default weekday and weekend start time distributions in emission rate
modeling for use in Atlanta metropolitan area regional emissions inventory development. The
section entitled "Impacts on MOBILE6.2 Modeling and Implications on Emissions Inventory
Development" explores the impacts on emission rates and on the regional emission inventory
when Commute Atlanta start time distributions replace the default MOBILE6.2 distributions in
modeling runs.
Engine Starts per Day
In undertaking the analyses reported herein, the research team noted a significant issue
associated with the use of average number of vehicle engine starts per day in the MOBILE6.2
model. The MOBILE6.2 model is used to predict emissions from vehicles that are operating on
the roadway (i.e., applied to VMT and VHT data). Hence, the average number of trips perve-
hicle per day should reflect the activity of those vehicles that are being driven on any given day.
Vehicle inactivity, the tendency for some vehicles to sit idle for multiple days, is a major issue in
using the instrumented vehicle and in using data collected through standard travel diary survey
efforts for the purposes of estimating starts per vehicle per day. If all participating Commute
Atlanta vehicles are used to derive average number of trips per day, LDVs make an average of
4.62 trips per vehicle per day. However, for vehicles operating on any given weekday (i.e., if all
vehicles that sit idle for the day are excluded from the calculation), Atlanta LDVs make an aver-
age of 5.29 trips per vehicle per day. The analyses prepared for this report employed the higher
values for average number of trips per vehicle per day for the region, based upon all active
vehicles (5.72 trips/day value for LDTs). We believe that most states would probably calculate
these values from multi-day travel diary studies in the same manner. Soak and start time distri-
butions only include vehicles that actually made a trip, so these distributions are not affected by
this issue.
Engine starts per day in Atlanta were significantly different from MOBILE6.2 default en-
gine starts per day (U.S. EPA, 2001). Commute Atlanta weekday engine starts per day were 27%
and 29% lower than MOBILE6.2 default weekday engine starts per day for LDVs and LDTs,
respectively. Commute Atlanta weekend engine stars per day were also 5% lower for LDVs and
4% lower for LDTs compared to the MOBILE6.2 default engine starts per day. Commute At-
lanta weekday and weekend engine starts per day for LDV and LOT could replace MOBILE6.2
default engine starts per day for emissions impact analysis (see the Section entitled Impacts on
MOBILE6.2 Modeling and Implications on Emissions Inventory Development). Demographic-
-------
parameter-weighted Commute Atlanta engine starts per day were similar to the Commute Atlanta
engine starts per day. The weighted engine starts per day were slightly higher for LDVs and
lower for LDTs than the Commute Atlanta engine starts per day. Table 5 shows weekday and
weekend engine starts per day for LDVs and LDTs using EPA default data, unweighted Com-
mute Atlanta data, and weighted Commute Atlanta.
Table 5: Weekday and Weekend Engine Starts per Day for LDVs and LDTs
Day Vehicle Type Data Source Starts/Day
Weekday
Weekend
LDV
LOT
LDV
LOT
EPA1
ATL2
WATL3
EPA
ATL
WATL
EPA
ATL
WATL
EPA
ATL
WATL
7.28
5.29
5.35
8.06
5.72
5.46
5.41
5.12
5.41
5.68
5.45
5.43
1} EPA: MOBILE6.2 Default Engine Starts per Day
2) ATL: Commute Atlanta Engine Starts per Day
3) WATL: Demographic Parameter Weighted Commute Atlanta Engine Starts per Day
Impacts on MOBILE6.2 Modeling and Emissions Inventory Development Implications
The research team conducted emissions impact analysis for emission rates and mobile
source emissions inventory development using start and soak time distributions and engine starts
per day from: MOBILE6.2 default files, 2004 Commute Atlanta data, and 2004 Commute At-
lanta data weighted by Atlanta demographic-parameters.
Impacts on MOBILE6.2 Modeling
The research team developed fifteen scenarios using mutually exclusive combinations
of MOBILE6.2 defaults, unweighted Commute Atlanta data, and weighted Commute Atlanta
data, for soak time distributions, start distributions, and engine starts per day. Based upon MO-
32
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BILE6.2 modeling results for these scenarios, exhaust engine start emission rates (at trip starts)
and evaporative hot soak emission rates (at trip ends) are significantly affected by the various
combinations of soak time distribution, start time distribution and engine starts per day.
LDV Exhaust Engine Start Emission Rates
The research team evaluated the effect on LDV engine start exhaust volatile organic com-
pound (VOC) emission rates (g/mi) across the fifteen scenarios (see Figure 25). In this figure,
"EPA" is MOBILE6.2 defaults, "ATL" is the unweighted Commute Atlanta data, and "WATL"
is the weighted Commute Atlanta data. Scenario 1 provides the results for engine start emis-
sion rates using MOBILE6.2 default control variables for all three inputs. Scenario 2 provides
the results for start emission rates using the Commute Atlanta soak time distribution and MO-
BILE6.2 start time distribution and starts per day. The LDV exhaust engine start emission rate
in the Scenario 2 was 15.9% greater than the Scenario 1. This is because Commute Atlanta soak
time distributions have longer average soak durations than MOBILE6.2 default soak time dura-
tions and longer soak durations yield higher engine start emission rates. Scenario 3 provides
start emission rates using the Commute Atlanta start distribution and MOBILE6.2 soak time
distribution and engine starts per day. The engine start emission rate in the Scenario 3 was only
1.2% greater than Scenario 1. The differences were not significant because Commute Atlanta
start time distributions are very similar to MOBILE6.2 default start time distributions. Scenario
4 examines engine start emission rate using Commute Atlanta engine starts per day and MO-
BILE6.2 default soak and start time distributions. The engine start emissions rate in Scenario 4
(grams/mile) was 27.3% lower than Scenario 1 because the average number of engine starts per
day from the Commute Atlanta data was 27.3% lower than the MOBILE6.2 default number of
engine starts per day.
It is important to note that the grams per start emission rate is unaffected by the number
of engine starts per day. The reduction in MOBILE6.2-predicted gram/mile emission rates arises
from the internal MOBILE6.2 calculations that translate embedded grams per start emission rates
into grams/mile emission rates for use in regional modeling undertaken by agencies that invento-
ry model using only mileage (i.e., by agencies that do not track the temporal and spatial locations
of engine starts). Average number of starts per day, multiplied by the embedded grams per start
emission rate by vehicle class, divided by average daily mileage accumulation by vehicle class
yields the grams/mile start emission rates. Modeling runs that employ a combination of default
and field data could produce seemingly reasonable results but are completely erroneous due to
the misunderstanding that engine starts per day and mileage accumulation rate data are co-de-
pendent. For example, in estimating the emissions inventory for Atlanta, modelers could choose
33
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to use the default MOBILE6.2 mileage accumulation rates with field-derived starts/day observa-
tions. If this occurs, the predicted inventory for engine start emissions (miles of travel multiplied
by the grams/mile engine start emission rate) is significantly lower when the engine start field
data are used, even though the emission rate in grams per start did not really change. It may be
prudent to require modelers to use default data unless field data are available for both engine
starts per day and mileage accumulation, as these parameters are not completely independent.
Nonattainment areas typically employ field data to estimate annual mileage accumulation
rates in their inventory modeling. Inspection and maintenance programs that record odometer
readings every year or two provide more estimates of mileage accumulation that are more ac-
curate than the default MOBILE6.2 distributions. However, few regions have access to field
data to estimate starts/day activity. It may be prudent to require modeling runs that use default
data for mileage accumulation to also use default data for engine starts per day. Similarly, it may
be prudent to require agencies that use regional mileage accumulation rates based upon inspec-
tion and maintenance data to collect sufficient field data to estimate regional engine starts per
day. Because engine start emission rates are unaffected by the number of engine starts per day,
and because the spatial and temporal distribution of engine start activity is critical to the regional
ozone modeling process, it seems even more prudent to urge regions to model engine starts and
running exhaust emissions separately, with engine start emissions calculated as number of starts
by vehicle class and model year multiplied by applicable grams per start emission rates (embed-
ded in the model). The next generation of the MOBILE model would need to be modified to pro-
vide applicable emission rate outputs to support this recommendation.
It is also important to note here that the number of engine starts per day and the shape of
soak time distributions are not independent. That is, when a vehicle makes more trips per day,
the soak times between trips must necessarily decline. Even start time distributions and soak
time distributions are not independent. Given that long soaks (greater than 8 hours) occur more
frequently associated with overnight inactivity, changes in start time distributions are correlated
with changes in soak time distributions (and engine starts per day). In effect, to properly com-
pare differences between the use of EPA default values and regionally-derived values (such as
from Commute Atlanta data) should only be done when all three distributions are taken from
regional data.
Start emission rates using soak time distributions, start time distributions, and engine
starts par day all taken from Commute Atlanta data (Scenario 8) were 17.4% lower than start
emission rates based upon MOBILE6.2 default data. Start emission rates using weighted Com-
mute Atlanta soak and start time distributions and engine starts per day were only about 1%
higher than the rates based upon unweighted Commute Atlanta data (and still more than 16.5%
34
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lower than the emission rates based upon EPA default values). Table 6 provides the percentage
differences across the unweighted commute data scenarios relative to the MOBILE6.2 default
analysis. Table 7 illustrates the marginal percentage difference in these emission rate changes
hen weighted Commute Atlanta data are used in lieu of unweighted Commute Atlanta data.
LDV Exhaust Engine Start Emission Rates {Trip Start} by Scenario
0.30
I °'25 •
£
« 0.20 •
0
•5 0.15-
.£
ui 0.10
0
X
0.05 -
n nn -
—
h
:
-
I
10 11 12 13 14 15
SOAK DIS TRIBUTION
START DISTRIBUTION
STARTDAY
EPA ATL EPA EPA ATL ATL EPA ATL ATL ATL WATL ATL WATL WATL WATL
EPA EPA ATL EPA ATL EPA ATL ATL ATL WATL ATL WATL ATL WATL WATL
EPA EPA EPA ATL EPA ATL ATL ATL WATL ATL ATL WATL WATL ATL WATL
Scenario
Figure 25: LDV Exhaust Engine Start Emission Rates for each Modeling Scenario
Table 6: Commute Atlanta LDV Exhaust Engine Start Emission Rate Changes Relative to MO-
BILE6.2 Default Data
Combination of Control Data
Scenario
Soak Time
Engine
Start Time
Engine Starts per Day
Change in Engine Start Emission
Rates Relative to MOBILE6.2
Default Data (%)
1
2
3
4
5
6
7
8
EPA
ATL
EPA
EPA
ATL
ATL
EPA
ATL
EPA
EPA
ATL
EPA
ATL
EPA
ATL
ATL
EPA
EPA
EPA
ATL
EPA
ATL
ATL
ATL
0.0
+15.9
+1.2
-27.3
+13.6
-15.8
-26.5
-17.4
35
-------
Table 7: Demographic-Parameter-Weighted LDV Exhaust Engine Start Emission Rate Changes
from Commute Atlanta Data
Combination of Control Data
Soak Time
Engine Start Engine Starts
Time per Day
Change in Engine Start Emission
Rates Relative to Commute Atlanta
Data (%)
8
9
10
11
12
13
14
15
ATL
ATL
ATL
WATL
ATL
WATL
WATL
WATL
ATL
ATL
WATL
ATL
WATL
ATL
WATL
WATL
ATL
WATL
ATL
ATL
WATL
WATL
ATL
WATL
0.0
+1.1
0.0
+0.1
+1.1
+1.2
0.0
+1.1
LDV Evaporative Hot Soak Emission Rates
In the MOBILE6.2 model, evaporative hot soak emission rates (g/mi) are only affected
by engine starts per day. Trip end evaporative hot soak emission rates are not affected by soak
and start time distributions. Because the number of Commute Atlanta engine starts per day was
27.3% lower than the MOBILE6.2 default engine starts per day, evaporative hot soak emission
rate with Commute Atlanta engine starts per day were 27.3% lower than emission rate with MO-
BILE6.2 default. Because the number of weighted Commute Atlanta engine starts per day was
1.1% greater than Commute Atlanta engine starts per day, evaporative hot soak emission rates
with weighted Commute Atlanta engine starts per day was 1.1% greater than emission rate with
unweighted Commute Atlanta engine starts per day. Figure 26 shows LDV evaporative hot soak
emission rates for scenarios.
36
-------
LDV Evaporative Hot Soak Emission Rates (Trip End} by Scenario
0.30
0.25
-2 0.20 +H
£ o.io -j-
111
o
0.05
0.00
I
e
10 11 12 13 14 15
SOAK DISTRIBUTION
START DISTRIBUTION
START DAY
EPA ATL EPA EPA ATL ATL EPA ATL ATL ATL WATL ATL WATL WATL WATL
EPA EPA ATL EPA ATL EPA ATL ATL ATL WATL ATL WATL ATL WATL WATL
EPA EPA EPA ATL EPA ATL ATL ATL WATL ATL ATL WATL WATL ATL WATL
Scenario
Figure 26: LDV Evaporative Hot Soak Emission Rates for each Modeling Scenario
Impacts on Atlanta Mobile Source Emissions Inventory Development
The research team evaluated impacts of using Commute Atlanta data in developing the
volatile organic compound (VOC) onroad mobile source emissions inventory for the 13-county
Atlanta metropolitan area. Because the State Implementation Plan (SIP) inventory for onroad
mobile source VOC emissions does not distinguish emissions by start, soak, and stabilized con-
tribution in Atlanta, the research team assumed that VOC emissions contributed by start and soak
activity are in proportion to the start and hot soak VOC emission rates for the calendar year 2005.
Because LDV and LOT contribute 90.2% (Morton, 2005) of total onroad mobile source VOC
emissions in the region in 2004, the contribution was multiplied by the total mobile source VOC
emissions to estimate LDV and LDT start and hot soak emissions. Using Mobile6.2 default soak
and engine start time distributions and engine starts per day, engine starts contribute 25.6% of the
VOC composite emission rates and hot soaks contribute 14.2% of VOC composite emission rates
37
-------
for calendar year 2005. These percentages were multiplied by the aggregated daily onroad VOC
inventory to estimate start and hot soak VOC emissions in the region. Because start and hot soak
VOC emission rates decreased by 17.4% and 27.3%, respectively, using Commute Atlanta soak
and engine start distributions and engine starts per day (see the previous section), these reduction
rates could be directly applied to estimate reduced VOC emissions by start and hot soak activi-
ties. By applying start and hot soak reduction rates, the research team estimates an 8.3% reduc-
tion in onroad VOC emissions. This implies that VOC emissions from Atlanta regional mobile
source emissions inventory appear to be significantly overestimated when MOBILE6.2 default
soak and engine start time distributions and engine starts per day are used for the Atlanta 13-
county metropolitan area.
Impact on Emissions Inventory Development in Other Cities
The research team conducted emissions inventory impact analysis for three additional
areas. For this impact analysis, the research team obtained MOBILE6.2 control files for: Gaston
County, NC, Mecklenburg County, NC, and York County, SC. The research team modeled en-
gine start and hot soak emission rates with the three county MOBILE6.2 control files and com-
pared them to emission rates modeled with the Atlanta 13-county MOBILE6.2 control file. Table
8 shows control parameters for the three counties and the 13-county Atlanta region. Appendix
C shows the MOBILE6.2 control files for Gaston County, NC, Mecklenburg County, NC, York
County, SC, and the 13-county Atlanta Metropolitan Area, GA.
Table 8: MOBILE6.2 Control Parameters for Gaston County, NC, Mecklenburg County,
NC, York County, SC, and the 13-county Atlanta Metropolitan Area, GA
Region or Counties
Parameters
Atlanta, GA Gaston, NC Mecklenburg, NC York, SC
Temperature (Min/Max)
Humidity (Min/Max)
Pressure
Fuel RVP
Fuel Program
Anti-Temp Program
I/M Program
Registration Distribution
Soak Time Distribution
Start Time Distribution
Starts per Day
72/94
32/70
28.98
7.0
YES
YES
YES
ATL1'
ATL
ATL
ATL
69.7/92.3
48.7/90.2
29.0
7.4
YES111
YES
YES
EPA11'
EPA
EPA
EPA
69.9/90.5
47.5/89.9
29.2
7.4
YES111
YES
YES
EPA
EPA
EPA
EPA
70.0/92.9
47.7/90.5
29.2
7.4
YES111
NO
NO
EPA
EPA
EPA
EPA
^MOBILE6.2 Control Parameters for the 13-County Atlanta Metropolitan Area
u) MOBILE6.2 Default Control Parameters
"') National Default Fuel Program
38
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Hourly ambient temperature and pressure for counties in Table 8 all differ slightly from the
13-county Atlanta region. Ambient humidity distribution for Atlanta was much drier than other
counties. Fuel RVP for Atlanta was 7.0 while 7.4 for other counties. Atlanta, Gaston, and Meck-
lenburg had inspection/maintenance (I/M) and anti-tempering programs. York County, SC had
no inspection and maintenance program in place (accounting for the large difference in emission
rates across the three counties). Atlanta used their own registration distribution, soak and start
time distributions, and engine start per day files while the other three counties used MOBILE6.2
default data files created by the U.S. EPA.
The research team modeled start and hot soak emission rates using the MOBILE6.2
control files for each county and then compared the emission rate outputs for each county to the
outputs for the Atlanta Metropolitan Area with Commute Atlanta data. Start and hot soak emis-
sion rates predicted for these three counties were higher than the emission rates predicted for the
Atlanta region. Start emission rates were 8.9%, 8.7%, and 25.8% higher than Atlanta for Gaston,
Mecklenburg, and York counties, respectively. Hot soak emission rates were 34.7%, 34.3%, and
35.6% higher for Gaston, Mecklenburg, and York counties, respectively. Table 9 shows the ratio
of start and hot soak emissions rates for the three cities compared to the Atlanta metropolitan
area emission rates.
Table 9: Ratios of Start and Hot Soak Emission Rates for Gaston County, NC, Mecklenburg
County, NC, and York County, SC (Using MOBILE6.2 Default Data) to the Emission Rates for
the Atlanta Metropolitan Area (Using Commute Atlanta Data)
Emission
Rates
Emission Rate Ratio of County Emission Rates (MOBILE6.2 Default Data)
to Atlanta Metropolitan Area Emission Rates (Commute Atlanta Data)
Gaston
Mecklenburg
York
Start
1.089
1.087
1.258
Hot Soak
1.347
1.343
1.356
Start and hot soak emission rates with EPA default soak and engine start time distribu-
tions and engine starts per day for the three counties were greater than those emissions rates with
the Commute Atlanta data files. If these three counties used the Commute Atlanta data files, pre-
dicted start emission rates would change by -9.2%, -9.2% and +3.9%, for Gaston, Mecklenburg,
and York, respectively. Similarly, hot soak emission rates change by -2.1%, -2.4% and -1.5% for
Gaston, Mecklenburg, and York, respectively. By applying the Commute Atlanta data files, start
and hot soak emission rates for the three counties were significantly lower than when the EPA de-
fault data files were employed in emission rate and emission inventory analysis. Table 10 shows
the three county LDV start and hot soak emission rate ratios to the 13-county Atlanta metropolis.
39
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Table 10: Ratios of Start and Hot Soak Emission Rates for Gaston County, NC, Mecklenburg
County, NC, and York County, SC (Using Commute Atlanta Data) to the Emission Rates for the
Atlanta Metropolitan Area (Using Commute Atlanta Data)
Emission
Type
Emission Rate Ratio of County Emission Rates (Commute Atlanta Data) to
Atlanta Metropolitan Area Emission Rates (Commute Atlanta Data)
Gaston
Mecklenburg
York
Start
0.898
0.898
1.039
Hot Soak
0.979
0.976
0.985
To investigate the counties' emission rate differences from Atlanta, the research team con-
ducted a sensitivity analysis of start and hot soak emission rates across various modeling param-
eters. For this analysis, the research team used MOBILE6.2 control files for York County and
the 13-county Atlanta area and developed five scenarios with five modeling parameters including
environmental parameters (temperature, humidity, and pressure), fuel RVP, state fuel programs, I/
M programs, and registration distributions. For each scenario, each of the five modeling param-
eters for York County was replaced one at a time by the applicable modeling parameter for the
Atlanta region. Environmental parameters, state fuel programs, I/M programs, and registration
distributions all impact start emission rates. Start emission rates changed by more than -15% and
+15% across the differences in I/M programs and registration distributions. Fuel program effects
were very small and ignorable. Fuel RVP did not affect engine start emission rates.
Differences in environmental parameters, fuel RVP, I/M programs, and registration distri-
butions all impacted hot soak emission rates. Environmental parameter differences yielded small
and ignorable effects on hot soak emission rates. Hot soak emission rate changes by fuel RVP
and I/M programs were moderate, hot soak emission rates decreased by about 5% after replacing
York County fuel RVP and I/M program parameters with the parameters from the Atlanta region.
However, hot soak emission rate increased more than 10% by replacing the registration distribu-
tions. Fuel program did not affect hot soak emission rate. Table 11 shows MOBILE6.2 control
parameters affecting start and hot soak emission rates by replacing York County control param-
eters to parameters for the Atlanta. YES means start and hot soak emission rates were affected
by control parameter, and NO means that no impact was noted.
Table 11: MOBILE6.2 Control Parameters Affecting Start and Hot Soak Emission Rates
P*| r**| iyi pf"Pf <2
Emission Environmental ^ , mrn ^ ,„ T™/r« Registration
_ _ Fuel RVP Fuel Pro- I/M Program ^.^ .,
-------
If Commute Atlanta soak and start distributions and engine start per day are applicable in
other regions, such as Gaston, Mecklenburg, and York counties, those counties can also expect
to predict significantly lower onroad VOC emissions. For example, if LDV and LDT contribute
the same percentage of total onroad mobile source VOC emissions as observed in the Atlanta
emission inventory (90.2%), Gaston, Mecklenburg and York counties would likely predict lower
onroad mobile source VOC inventory emissions by 7.76%, 7.76%, and 7.80%, respectively.
Conclusions
The Georgia Tech research team developed soak and start time distributions and engine
starts per day using LDV and LDT trip data collected in the Commute Atlanta study during 2004.
Commute Atlanta soak and start time distributions show similar distribution patterns to MO-
BILE6.2 default soak and start time distributions. However, Commute Atlanta soak time distri-
butions exhibited longer soak durations (i.e., especially for soaks greater than 720 minutes) with
a wider stretch from 3 a.m. to 11 a.m. and 4 a.m. to 2 p.m. for weekday and weekend. Commute
Atlanta start time distributions gradually decrease from 6 p.m. to 2 a.m. and increase from 2 a.m.,
while MOBILE6.2 default start time distributions sharply decrease at 6 p.m. to 7 p.m. and show
more flat patterns from 7 p.m. to 5 a.m. Commute Atlanta engine starts per day for LDVs were
significantly lower in Atlanta than are currently employed as MOBILE6.2 defaults: 27% lower
on weekdays and 5% lower on weekends.
Commute Atlanta soak and start time distributions and engine starts per day significantly
influence VOC start and hot soak emission rates and mobile source emissions inventory devel-
opment. By applying Commute Atlanta soak and start time distributions and engine starts per
day in MOBILE6.2 emission rate modeling, engine start VOC emission rates are predicted to be
17.4% lower and hot soak VOC emission rates are predicted to be 27.3% lower. These signifi-
cant reductions can account for an 8.3% reduction in predicted onroad VOC emissions in the 13-
county Atlanta metropolitan area. If the Commute Atlanta soak and start time distributions and
engine starts per day are applicable to other cities, predicted onroad mobile source VOC emis-
sions inventories in these regions would also significantly decrease. Given the effect on regional
emissions inventories predictions, the results of the study indicate that additional start/soak data
collection and analytical efforts are warranted and that longitudinal instrumented vehicle studies
may be the preferred method for collecting such data.
41
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Appendix A: Commute Atlanta Soak Time Distributions
42
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Appendix Al: Commute Atlanta Weekday Soak Time Distributions
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
S 22
O 23
A 24
K 25
C 26
O 27
D 28
E 29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
0.0287
0.0299
0.0267
0.0193
0.0147
0.0093
0.0062
0.0037
0.0030
0.0031
0.0029
0.0025
0.0015
0.0011
0.0012
0.0018
0.0018
0.0013
0.0015
0.0015
0.0016
0.0018
0.0016
0.0023
0.0015
0.0012
0.0010
0.0008
0.0010
0.0007
0.0026
0.0023
0.0022
0.0018
0.0008
0.0013
0.0004
0.0007
0.0007
0.0010
0.0007
0.0012
0.0010
0.0007
0.0008
0.0112
0.0062
0.0067
0.0114
0.0113
0.0031
0.0022
0.0032
0.0049
0.0074
0.0139
0.0137
0.0213
0.0216
0.0199
0.0247
0.0305
0.0361
0.0391
0.0440
0.0508
0.0490
0.3741
7
0.0332
0.0350
0.0293
0.0212
0.0157
0.0123
0.0093
0.0070
0.0054
0.0050
0.0041
0.0031
0.0029
0.0027
0.0026
0.0024
0.0025
0.0020
0.0020
0.0019
0.0020
0.0013
0.0018
0.0014
0.0017
0.0014
0.0017
0.0015
0.0014
0.0015
0.0029
0.0033
0.0020
0.0027
0.0027
0.0020
0.0016
0.0018
0.0018
0.0012
0.0016
0.0018
0.0015
0.0013
0.0017
0.0179
0.0055
0.0043
0.0050
0.0080
0.0078
0.0052
0.0011
0.0032
0.0026
0.0028
0.0062
0.0127
0.0182
0.0175
0.0177
0.0204
0.0298
0.0361
0.0409
0.0434
0.0435
0.4046
8
0.0381
0.0383
0.0367
0.0290
0.0220
0.0175
0.0142
0.0133
0.0106
0.0091
0.0084
0.0073
0.0062
0.0058
0.0053
0.0049
0.0050
0.0055
0.0042
0.0046
0.0036
0.0040
0.0031
0.0037
0.0031
0.0030
0.0028
0.0036
0.0031
0.0033
0.0055
0.0055
0.0051
0.0056
0.0055
0.0050
0.0050
0.0040
0.0047
0.0039
0.0036
0.0038
0.0033
0.0035
0.0039
0.0308
0.0129
0.0118
0.0054
0.0035
0.0051
0.0058
0.0045
0.0030
0.0016
0.0018
0.0025
0.0039
0.0061
0.0101
0.0146
0.0178
0.0182
0.0167
0.0204
0.0266
0.0307
0.3592
9
0.0401
0.0444
0.0441
0.0360
0.0275
0.0236
0.0182
0.0169
0.0138
0.0125
0.0105
0.0088
0.0088
0.0081
0.0068
0.0072
0.0066
0.0074
0.0062
0.0056
0.0048
0.0039
0.0043
0.0048
0.0051
0.0047
0.0045
0.0049
0.0039
0.0029
0.0078
0.0071
0.0066
0.0064
0.0063
0.0048
0.0052
0.0053
0.0050
0.0044
0.0048
0.0048
0.0043
0.0044
0.0051
0.0557
0.0319
0.0168
0.0063
0.0043
0.0035
0.0032
0.0035
0.0041
0.0045
0.0026
0.0016
0.0017
0.0021
0.0026
0.0044
0.0074
0.0122
0.0105
0.0112
0.0114
0.0143
0.3051
10
0.0359
0.0401
0.0438
0.0371
0.0305
0.0251
0.0219
0.0177
0.0161
0.0136
0.0129
0.0118
0.0113
0.0105
0.0109
0.0085
0.0084
0.0079
0.0087
0.0075
0.0072
0.0074
0.0058
0.0062
0.0053
0.0063
0.0051
0.0049
0.0056
0.0049
0.0104
0.0094
0.0096
0.0080
0.0083
0.0076
0.0071
0.0076
0.0080
0.0072
0.0054
0.0058
0.0061
0.0047
0.0063
0.0685
0.0405
0.0273
0.0204
0.0103
0.0062
0.0041
0.0026
0.0024
0.0023
0.0033
0.0034
0.0023
0.0011
0.0006
0.0014
0.0020
0.0037
0.0065
0.0073
0.0076
0.0075
0.2184
11
0.0353
0.0376
0.0385
0.0327
0.0296
0.0256
0.0206
0.0191
0.0167
0.0154
0.0139
0.0128
0.0119
0.0105
0.0102
0.0100
0.0096
0.0088
0.0087
0.0082
0.0076
0.0068
0.0076
0.0068
0.0077
0.0068
0.0065
0.0060
0.0061
0.0054
0.0113
0.0098
0.0106
0.0091
0.0092
0.0079
0.0080
0.0068
0.0069
0.0067
0.0065
0.0058
0.0064
0.0062
0.0058
0.0589
0.0370
0.0322
0.0326
0.0349
0.0349
0.0227
0.0146
0.0109
0.0060
0.0026
0.0020
0.0021
0.0018
0.0008
0.0006
0.0007
0.0007
0.0012
0.0024
0.0035
0.0041
0.1332
MOBILE6.2 HOUR OF DAY
0.0332
0.0365
0.0383
0.0331
0.0268
0.0252
0.0199
0.0191
0.0147
0.0147
0.0130
0.0128
0.0116
0.0118
0.0109
0.0097
0.0096
0.0096
0.0084
0.0087
0.0089
0.0080
0.0082
0.0069
0.0079
0.0072
0.0081
0.0076
0.0067
0.0071
0.0146
0.0144
0.0129
0.0130
0.0116
0.0113
0.0101
0.0099
0.0099
0.0091
0.0087
0.0084
0.0065
0.0058
0.0064
0.0625
0.0329
0.0289
0.0268
0.0256
0.0294
0.0371
0.0246
0.0141
0.0088
0.0050
0.0019
0.0013
0.0015
0.0012
0.0014
0.0007
0.0004
0.0006
0.0004
0.0009
0.0012
0.0959
0.0331
0.0386
0.0387
0.0355
0.0285
0.0244
0.0203
0.0189
0.0180
0.0148
0.0144
0.0122
0.0120
0.0122
0.0116
0.0096
0.0108
0.0096
0.0099
0.0089
0.0091
0.0076
0.0082
0.0087
0.0077
0.0073
0.0071
0.0078
0.0077
0.0073
0.0136
0.0136
0.0134
0.0111
0.0116
0.0115
0.0108
0.0093
0.0100
0.0099
0.0087
0.0083
0.0083
0.0081
0.0073
0.0743
0.0416
0.0271
0.0240
0.0180
0.0181
0.0216
0.0199
0.0176
0.0143
0.0080
0.0037
0.0023
0.0033
0.0023
0.0036
0.0037
0.0011
0.0007
0.0004
0.0008
0.0006
0.0768
0.0356
0.0379
0.0399
0.0350
0.0303
0.0225
0.0215
0.0198
0.0158
0.0151
0.0126
0.0133
0.0124
0.0123
0.0110
0.0111
0.0100
0.0097
0.0088
0.0098
0.0086
0.0093
0.0074
0.0074
0.0066
0.0070
0.0068
0.0068
0.0068
0.0069
0.0105
0.0123
0.0105
0.0105
0.0104
0.0096
0.0094
0.0077
0.0076
0.0079
0.0081
0.0078
0.0075
0.0067
0.0063
0.0715
0.0421
0.0330
0.0261
0.0178
0.0133
0.0154
0.0117
0.0173
0.0134
0.0158
0.0123
0.0128
0.0116
0.0060
0.0083
0.0083
0.0015
0.0011
0.0012
0.0008
0.0005
0.0671
0.0358
0.0400
0.0424
0.0333
0.0283
0.0247
0.0221
0.0179
0.0167
0.0153
0.0135
0.0134
0.0113
0.0105
0.0104
0.0117
0.0097
0.0096
0.0091
0.0077
0.0075
0.0080
0.0072
0.0069
0.0070
0.0066
0.0064
0.0058
0.0053
0.0054
0.0099
0.0092
0.0098
0.0092
0.0083
0.0075
0.0080
0.0077
0.0066
0.0071
0.0069
0.0064
0.0065
0.0059
0.0053
0.0646
0.0371
0.0306
0.0288
0.0236
0.0181
0.0158
0.0104
0.0100
0.0109
0.0109
0.0131
0.0145
0.0224
0.0240
0.0247
0.0131
0.0061
0.0021
0.0013
0.0009
0.0010
0.0524
0.0319
0.0380
0.0384
0.0345
0.0290
0.0229
0.0193
0.0168
0.0167
0.0146
0.0133
0.0128
0.0116
0.0111
0.0096
0.0090
0.0095
0.0088
0.0081
0.0081
0.0072
0.0080
0.0073
0.0072
0.0064
0.0064
0.0064
0.0052
0.0054
0.0051
0.0098
0.0092
0.0096
0.0085
0.0076
0.0081
0.0079
0.0068
0.0059
0.0068
0.0057
0.0059
0.0050
0.0053
0.0051
0.0615
0.0374
0.0304
0.0258
0.0304
0.0312
0.0232
0.0135
0.0092
0.0070
0.0075
0.0085
0.0107
0.0151
0.0183
0.0378
0.0335
0.0152
0.0084
0.0028
0.0008
0.0007
0.0353
0.0340
0.0377
0.0365
0.0334
0.0263
0.0214
0.0194
0.0172
0.0165
0.0154
0.0122
0.0135
0.0115
0.0099
0.0102
0.0098
0.0090
0.0077
0.0083
0.0078
0.0071
0.0064
0.0064
0.0057
0.0061
0.0057
0.0061
0.0059
0.0057
0.0045
0.0102
0.0096
0.0083
0.0086
0.0080
0.0079
0.0076
0.0073
0.0065
0.0064
0.0066
0.0061
0.0061
0.0059
0.0054
0.0629
0.0417
0.0330
0.0244
0.0251
0.0279
0.0349
0.0205
0.0145
0.0088
0.0058
0.0076
0.0079
0.0102
0.0157
0.0195
0.0341
0.0215
0.0138
0.0063
0.0020
0.0011
0.0331
18
0.0327
0.0354
0.0369
0.0295
0.0248
0.0211
0.0183
0.0165
0.0155
0.0140
0.0122
0.0111
0.0106
0.0113
0.0097
0.0097
0.0078
0.0090
0.0083
0.0081
0.0065
0.0071
0.0066
0.0073
0.0064
0.0064
0.0064
0.0060
0.0060
0.0058
0.0110
0.0116
0.0102
0.0099
0.0093
0.0089
0.0094
0.0085
0.0088
0.0088
0.0082
0.0078
0.0073
0.0078
0.0073
0.0822
0.0517
0.0377
0.0289
0.0229
0.0190
0.0175
0.0177
0.0169
0.0124
0.0092
0.0078
0.0072
0.0069
0.0093
0.0106
0.0146
0.0144
0.0121
0.0108
0.0073
0.0036
0.0374
19
0.0317
0.0359
0.0369
0.0286
0.0247
0.0199
0.0190
0.0146
0.0142
0.0154
0.0133
0.0113
0.0106
0.0117
0.0098
0.0077
0.0082
0.0080
0.0076
0.0075
0.0078
0.0078
0.0059
0.0061
0.0066
0.0065
0.0063
0.0061
0.0049
0.0066
0.0122
0.0109
0.0114
0.0098
0.0101
0.0102
0.0096
0.0103
0.0112
0.0108
0.0098
0.0090
0.0088
0.0098
0.0085
0.1004
0.0632
0.0429
0.0312
0.0215
0.0178
0.0147
0.0113
0.0120
0.0101
0.0095
0.0075
0.0060
0.0058
0.0083
0.0075
0.0079
0.0086
0.0088
0.0072
0.0053
0.0054
0.0330
20
0.0336
0.0376
0.0351
0.0312
0.0264
0.0231
0.0158
0.0150
0.0135
0.0132
0.0117
0.0100
0.0100
0.0099
0.0085
0.0094
0.0072
0.0085
0.0077
0.0075
0.0068
0.0067
0.0055
0.0064
0.0058
0.0055
0.0060
0.0052
0.0046
0.0055
0.0101
0.0077
0.0100
0.0081
0.0087
0.0085
0.0090
0.0071
0.0083
0.0082
0.0088
0.0082
0.0083
0.0081
0.0088
0.1173
0.0933
0.0631
0.0418
0.0268
0.0172
0.0127
0.0092
0.0085
0.0065
0.0055
0.0046
0.0041
0.0049
0.0039
0.0032
0.0042
0.0041
0.0061
0.0054
0.0043
0.0033
0.0291
21
0.0371
0.0402
0.0328
0.0252
0.0221
0.0147
0.0 53
0.0 31
0.0 18
0.0 08
0.0 25
0.0 04
0.0085
0.0074
0.0081
0.0064
0.0060
0.0057
0.0059
0.0063
0.0043
0.0056
0.0059
0.0044
0.0044
0.0053
0.0049
0.0046
0.0032
0.0035
0.0085
0.0064
0.0078
0.0071
0.0059
0.0078
0.0065
0.0073
0.0067
0.0061
0.0072
0.0076
0.0058
0.0052
0.0055
0.0820
0.0777
0.0922
0.0737
0.0498
0.0312
0.0218
0.0163
0.0125
0.0097
0.0085
0.0054
0.0075
0.0045
0.0038
0.0063
0.0034
0.0031
0.0027
0.0029
0.0030
0.0030
0.0316
22
0.0264
0.0302
0.0239
0.0203
0.0162
0.0109
0.0114
0.0099
0.0068
0.0070
0.0075
0.0060
0.0061
0.0064
0.0056
0.0050
0.0039
0.0037
0.0041
0.0044
0.0035
0.0036
0.0027
0.0038
0.0034
0.0035
0.0032
0.0026
0.0019
0.0016
0.0054
0.0038
0.0057
0.0054
0.0047
0.0057
0.0066
0.0041
0.0044
0.0046
0.0056
0.0041
0.0045
0.0061
0.0062
0.0642
0.0592
0.0558
0.0576
0.0638
0.0572
0.0422
0.0315
0.0260
0.0214
0.0206
0.0182
0.0117
0.0114
0.0096
0.0075
0.0084
0.0078
0.0069
0.0045
0.0042
0.0044
0.0839
23
0.0206
0.0199
0.0155
0.0135
0.0088
0.0069
0.0063
0.0059
0.0046
0.0039
0.0034
0.0042
0.0034
0.0037
0.0022
0.0030
0.0033
0.0034
0.0031
0.0041
0.0033
0.0025
0.0024
0.0014
0.0024
0.0026
0.0028
0.0016
0.0017
0.0021
0.0038
0.0034
0.0026
0.0034
0.0041
0.0022
0.0050
0.0043
0.0029
0.0030
0.0039
0.0033
0.0029
0.0034
0.0026
0.0457
0.0528
0.0478
0.0461
0.0478
0.0477
0.0525
0.0435
0.0402
0.0295
0.0311
0.0245
0.0224
0.0193
0.0178
0.0296
0.0159
0.0086
0.0063
0.0069
0.0080
0.0052
0.1373
0
0.0311
0.0235
0.0246
0.0181
0.0123
0.0094
0.0069
0.0043
0.0076
0.0043
0.0040
0.0033
0.0069
0.0040
0.0054
0.0018
0.0025
0.0014
0.0047
0.0043
0.0025
0.0022
0.0040
0.0018
0.0033
0.0040
0.0040
0.0025
0.0022
0.0018
0.0054
0.0047
0.0051
0.0029
0.0040
0.0040
0.0036
0.0051
0.0043
0.0047
0.0025
0.0054
0.0054
0.0036
0.0040
0.0553
0.0387
0.0520
0.0484
0.0441
0.0434
0.0405
0.0311
0.0390
0.0611
0.0249
0.0271
0.0202
0.0155
0.0206
0.0228
0.0090
0.0098
0.0119
0.0087
0.0054
0.0083
0.0889
1
0.0410
0.0271
0.0217
0.0193
0.0170
0.0124
0.0085
0.0062
0.0062
0.0039
0.0039
0.0023
0.0046
0.0085
0.0039
0.0031
0.0023
0.0062
0.0062
0.0023
0.0039
0.0046
0.0039
0.0031
0.0008
0.0031
0.0054
0.0031
0.0000
0.0008
0.0070
0.0062
0.0039
0.0008
0.0046
0.0031
0.0046
0.0046
0.0062
0.0046
0.0031
0.0023
0.0054
0.0031
0.0023
0.0449
0.0588
0.0626
0.0472
0.0348
0.0503
0.0302
0.0178
0.0317
0.0263
0.0294
0.0302
0.0232
0.0224
0.0240
0.0178
0.0232
0.0162
0.0108
0.0077
0.0046
0.0039
0.0851
2
0.0333
0.0241
0.0276
0.0218
0.0207
0.0092
0.0069
0.0092
0.0092
0.0103
0.0023
0.0046
0.0046
0.0011
0.0023
0.0034
0.0000
0.0023
0.0011
0.0046
0.0000
0.0011
0.0034
0.0011
0.0046
0.0000
0.0011
0.0011
0.0023
0.0023
0.0000
0.0023
0.0023
0.0069
0.0057
0.0034
0.0011
0.0034
0.0000
0.0023
0.0034
0.0069
0.0011
0.0057
0.0057
0.0322
0.0425
0.0425
0.0379
0.0402
0.0322
0.0368
0.0575
0.0402
0.0264
0.0402
0.0368
0.0333
0.0218
0.0207
0.0195
0.0149
0.0149
0.0230
0.0126
0.0046
0.0080
0.0943
3
0.0118
0.0050
0.0091
0.0064
0.0027
0.0010
0.0020
0.0013
0.0013
0.0013
0.0010
0.0010
0.0017
0.0013
0.0017
0.0013
0.0013
0.0010
0.0030
0.0007
0.0017
0.0003
0.0007
0.0003
0.0013
0.0003
0.0000
0.0000
0.0007
0.0003
0.0007
0.0000
0.0010
0.0003
0.0010
0.0003
0.0003
0.0003
0.0003
0.0013
0.0017
0.0003
0.0003
0.0010
0.0003
0.0081
0.0111
0.0087
0.0118
0.0232
0.0672
0.0521
0.0494
0.0373
0.0252
0.0313
0.0360
0.0349
0.0376
0.0380
0.0343
0.0383
0.0390
0.0373
0.0276
0.0262
0.0255
0.2288
4
0.0097
0.0090
0.0041
0.0041
0.0026
0.0019
0.0004
0.0019
0.0022
0.0019
0.0030
0.0007
0.0007
0.0011
0.0015
0.0007
0.0007
0.0000
0.0007
0.0011
0.0007
0.0000
0.0000
0.0007
0.0007
0.0000
0.0004
0.0004
0.0007
0.0007
0.0007
0.0007
0.0004
0.0004
0.0007
0.0015
0.0011
0.0000
0.0004
0.0000
0.0011
0.0011
0.0004
0.0000
0.0004
0.0064
0.0056
0.0101
0.0067
0.0052
0.0105
0.0464
0.0876
0.0472
0.0341
0.0367
0.0345
0.0348
0.0337
0.0326
0.0337
0.0326
0.0333
0.0330
0.0315
0.0352
0.0285
0.2783
5
0.0199
0.0214
0.0146
0.0122
0.0088
0.0034
0.0032
0.0032
0.0019
0.0015
0.0011
0.0009
0.0006
0.0004
0.0007
0.0011
0.0009
0.0009
0.0004
0.0009
0.0004
0.0004
0.0007
0.0007
0.0006
0.0006
0.0006
0.0002
0.0011
0.0006
0.0007
0.0002
0.0009
0.0002
0.0004
0.0015
0.0007
0.0006
0.0006
0.0004
0.0002
0.0011
0.0006
0.0011
0.0004
0.0124
0.0079
0.0062
0.0034
0.0032
0.0045
0.0028
0.0079
0.0193
0.0262
0.0485
0.0217
0.0182
0.0270
0.0336
0.0345
0.0405
0.0463
0.0482
0.0534
0.0469
0.0598
0.3143
43
-------
Appendix A2: Commute Atlanta Weekend Soak Time Distributions
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
S 22
O 23
A 24
K 25
C 26
O 27
D 28
E 29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
0.0341
0.0468
0.0412
0.0199
0.0185
0.0106
0.0078
0.0064
0.0057
0.0035
0.0057
0.0043
0.0050
0.0014
0.0028
0.0007
0.0028
0.0014
0.0035
0.0007
0.0035
0.0014
0.0014
0.0007
0.0014
0.0014
0.0021
0.0021
0.0007
0.0014
0.0021
0.0007
0.0014
0.0035
0.0014
0.0007
0.0000
0.0000
0.0021
0.0000
0.0007
0.0000
0.0000
0.0000
0.0007
0.0057
0.0057
0.0050
0.0064
0.0092
0.0035
0.0014
0.0050
0.0057
0.0057
0.0170
0.0142
0.0220
0.0305
0.0376
0.0348
0.0312
0.0319
0.0419
0.0412
0.0369
0.0277
0.3272
7
0.0333
0.0316
0.0336
0.0282
0.0146
0.0102
0.0119
0.0061
0.0058
0.0058
0.0048
0.0048
0.0031
0.0034
0.0041
0.0044
0.0027
0.0044
0.0031
0.0044
0.0027
0.0041
0.0027
0.0048
0.0037
0.0024
0.0034
0.0024
0.0024
0.0027
0.0068
0.0071
0.0020
0.0024
0.0014
0.0048
0.0020
0.0017
0.0027
0.0007
0.0017
0.0017
0.0031
0.0007
0.0007
0.0126
0.0031
0.0034
0.0071
0.0071
0.0122
0.0061
0.0027
0.0010
0.0007
0.0034
0.0068
0.0119
0.0197
0.0302
0.0367
0.0333
0.0299
0.0360
0.0353
0.0272
0.0418
0.3408
8
0.0293
0.0364
0.0331
0.0254
0.0205
0.0175
0.0119
0.0098
0.0101
0.0089
0.0048
0.0047
0.0053
0.0056
0.0041
0.0050
0.0048
0.0035
0.0039
0.0033
0.0032
0.0033
0.0047
0.0038
0.0047
0.0023
0.0036
0.0020
0.0026
0.0024
0.0047
0.0053
0.0050
0.0042
0.0039
0.0026
0.0032
0.0039
0.0036
0.0023
0.0035
0.0023
0.0027
0.0032
0.0023
0.0197
0.0099
0.0066
0.0059
0.0026
0.0120
0.0205
0.0199
0.0015
0.0018
0.0023
0.0026
0.0048
0.0060
0.0107
0.0169
0.0224
0.0259
0.0302
0.0241
0.0271
0.0278
0.3665
9
0.0287
0.0333
0.0355
0.0299
0.0242
0.0166
0.0149
0.0141
0.0103
0.0113
0.0100
0.0076
0.0081
0.0064
0.0061
0.0068
0.0061
0.0059
0.0044
0.0055
0.0045
0.0047
0.0053
0.0037
0.0041
0.0053
0.0045
0.0036
0.0045
0.0046
0.0073
0.0059
0.0068
0.0074
0.0046
0.0055
0.0056
0.0051
0.0039
0.0031
0.0034
0.0043
0.0039
0.0032
0.0041
0.0458
0.0200
0.0079
0.0073
0.0080
0.0067
0.0042
0.0028
0.0026
0.0037
0.0021
0.0014
0.0015
0.0029
0.0033
0.0051
0.0085
0.0139
0.0134
0.0190
0.0198
0.0200
0.3752
10
0.0338
0.0392
0.0357
0.0313
0.0251
0.0203
0.0178
0.0164
0.0141
0.0140
0.0114
0.0120
0.0109
0.0080
0.0093
0.0078
0.0079
0.0062
0.0084
0.0069
0.0069
0.0063
0.0063
0.0061
0.0053
0.0058
0.0046
0.0047
0.0051
0.0046
0.0112
0.0097
0.0089
0.0066
0.0074
0.0071
0.0064
0.0066
0.0064
0.0056
0.0050
0.0056
0.0053
0.0041
0.0053
0.0676
0.0376
0.0236
0.0134
0.0092
0.0028
0.0020
0.0009
0.0012
0.0034
0.0020
0.0017
0.0010
0.0014
0.0020
0.0017
0.0033
0.0041
0.0081
0.0111
0.0117
0.0146
0.2821
11
0.0335
0.0359
0.0422
0.0337
0.0242
0.0209
0.0189
0.0177
0.0161
0.0168
0.0138
0.0153
0.0105
0.0105
0.0105
0.0108
0.0095
0.0093
0.0080
0.0087
0.0080
0.0081
0.0074
0.0078
0.0063
0.0058
0.0054
0.0066
0.0058
0.0057
0.0094
0.0100
0.0098
0.0087
0.0092
0.0084
0.0075
0.0087
0.0065
0.0067
0.0085
0.0063
0.0063
0.0058
0.0052
0.0723
0.0523
0.0318
0.0256
0.0139
0.0061
0.0042
0.0024
0.0012
0.0008
0.0007
0.0010
0.0018
0.0013
0.0007
0.0008
0.0016
0.0013
0.0018
0.0028
0.0043
0.0066
0.2146
MOBILE6.2 HOUR OF DAY
12 13 14
0.0309
0.0351
0.0378
0.0324
0.0258
0.0192
0.0183
0.0174
0.0160
0.0134
0.0119
0.0121
0.0124
0.0127
0.0115
0.0124
0.0102
0.0094
0.0092
0.0076
0.0086
0.0071
0.0078
0.0087
0.0084
0.0077
0.0060
0.0066
0.0061
0.0054
0.0123
0.0104
0.0122
0.0096
0.0088
0.0081
0.0099
0.0069
0.0083
0.0075
0.0068
0.0080
0.0058
0.0068
0.0065
0.0867
0.0545
0.0374
0.0379
0.0236
0.0135
0.0098
0.0059
0.0048
0.0017
0.0009
0.0004
0.0002
0.0006
0.0013
0.0011
0.0010
0.0006
0.0015
0.0009
0.0020
0.0029
0.1550
0.0320
0.0369
0.0382
0.0285
0.0236
0.0200
0.0185
0.0185
0.0159
0.0172
0.0146
0.0126
0.0130
0.0130
0.0113
0.0113
0.0097
0.0105
0.0091
0.0093
0.0094
0.0075
0.0071
0.0093
0.0089
0.0077
0.0093
0.0066
0.0072
0.0067
0.0139
0.0137
0.0137
0.0117
0.0108
0.0128
0.0113
0.0108
0.0108
0.0096
0.0109
0.0077
0.0104
0.0071
0.0074
0.0815
0.0408
0.0349
0.0287
0.0172
0.0137
0.0103
0.0090
0.0070
0.0039
0.0024
0.0022
0.0009
0.0005
0.0005
0.0011
0.0019
0.0005
0.0005
0.0007
0.0013
0.0014
0.1331
0.0316
0.0386
0.0364
0.0335
0.0275
0.0245
0.0213
0.0185
0.0160
0.0172
0.0147
0.0137
0.0123
0.0117
0.0130
0.0119
0.0114
0.0114
0.0102
0.0095
0.0098
0.0087
0.0076
0.0088
0.0075
0.0084
0.0079
0.0079
0.0078
0.0065
0.0130
0.0128
0.0123
0.0109
0.0122
0.0111
0.0091
0.0098
0.0096
0.0093
0.0084
0.0076
0.0074
0.0065
0.0083
0.0825
0.0515
0.0358
0.0221
0.0205
0.0148
0.0091
0.0083
0.0082
0.0063
0.0058
0.0025
0.0029
0.0016
0.0007
0.0005
0.0009
0.0007
0.0006
0.0003
0.0007
0.0007
0.1087
15
0.0312
0.0382
0.0362
0.0319
0.0263
0.0226
0.0222
0.0193
0.0147
0.0146
0.0148
0.0133
0.0134
0.0146
0.0120
0.0107
0.0098
0.0100
0.0112
0.0092
0.0096
0.0084
0.0093
0.0083
0.0088
0.0080
0.0070
0.0083
0.0072
0.0067
0.0125
0.0135
0.0138
0.0096
0.0109
0.0112
0.0095
0.0085
0.0090
0.0085
0.0079
0.0073
0.0073
0.0067
0.0074
0.0788
0.0518
0.0436
0.0308
0.0229
0.0153
0.0127
0.0121
0.0069
0.0056
0.0058
0.0057
0.0038
0.0027
0.0024
0.0024
0.0008
0.0002
0.0003
0.0006
0.0007
0.0007
0.0915
16
0.0339
0.0406
0.0379
0.0313
0.0262
0.0233
0.0220
0.0185
0.0174
0.0172
0.0126
0.0127
0.0129
0.0124
0.0110
0.0115
0.0104
0.0080
0.0097
0.0093
0.0081
0.0089
0.0084
0.0083
0.0078
0.0076
0.0072
0.0058
0.0072
0.0061
0.0132
0.0142
0.0118
0.0083
0.0091
0.0088
0.0098
0.0095
0.0082
0.0079
0.0069
0.0070
0.0069
0.0072
0.0065
0.0704
0.0520
0.0397
0.0330
0.0257
0.0216
0.0185
0.0142
0.0094
0.0077
0.0063
0.0062
0.0054
0.0055
0.0044
0.0024
0.0053
0.0016
0.0007
0.0005
0.0000
0.0003
0.0797
17
0.0319
0.0337
0.0363
0.0294
0.0267
0.0230
0.0198
0.0167
0.0134
0.0151
0.0134
0.0130
0.0133
0.0112
0.0109
0.0098
0.0093
0.0117
0.0088
0.0091
0.0094
0.0103
0.0092
0.0073
0.0084
0.0082
0.0080
0.0083
0.0073
0.0071
0.0125
0.0101
0.0106
0.0113
0.0118
0.0091
0.0080
0.0089
0.0082
0.0081
0.0087
0.0073
0.0070
0.0057
0.0063
0.0786
0.0490
0.0369
0.0310
0.0274
0.0197
0.0240
0.0179
0.0148
0.0116
0.0082
0.0097
0.0044
0.0057
0.0066
0.0040
0.0042
0.0025
0.0010
0.0011
0.0005
0.0003
0.0673
18
0.0307
0.0328
0.0322
0.0298
0.0263
0.0215
0.0177
0.0142
0.0148
0.0132
0.0143
0.0114
0.0115
0.0090
0.0102
0.0096
0.0100
0.0076
0.0087
0.0076
0.0072
0.0072
0.0073
0.0066
0.0064
0.0066
0.0073
0.0066
0.0062
0.0058
0.0102
0.0121
0.0091
0.0086
0.0106
0.0098
0.0104
0.0080
0.0087
0.0091
0.0089
0.0088
0.0077
0.0091
0.0072
0.0876
0.0519
0.0415
0.0367
0.0252
0.0210
0.0220
0.0191
0.0173
0.0155
0.0126
0.0136
0.0085
0.0075
0.0048
0.0053
0.0040
0.0039
0.0030
0.0018
0.0006
0.0006
0.0573
19
0.0326
0.0320
0.0347
0.0277
0.0259
0.0201
0.0202
0.0156
0.0151
0.0143
0.0152
0.0096
0.0100
0.0070
0.0088
0.0096
0.0088
0.0072
0.0086
0.0060
0.0087
0.0058
0.0060
0.0060
0.0068
0.0068
0.0063
0.0060
0.0055
0.0061
0.0105
0.0099
0.0113
0.0097
0.0091
0.0091
0.0086
0.0088
0.0093
0.0083
0.0093
0.0082
0.0083
0.0068
0.0072
0.1041
0.0677
0.0440
0.0361
0.0282
0.0213
0.0183
0.0184
0.0146
0.0141
0.0104
0.0083
0.0064
0.0063
0.0069
0.0037
0.0044
0.0031
0.0029
0.0028
0.0014
0.0010
0.0480
20
0.0349
0.0374
0.0351
0.0263
0.0201
0.0222
0.0194
0.0143
0.0134
0.0139
0.0152
0.0092
0.0115
0.0108
0.0109
0.0093
0.0079
0.0099
0.0079
0.0076
0.0069
0.0074
0.0062
0.0095
0.0041
0.0065
0.0041
0.0055
0.0041
0.0053
0.0095
0.0092
0.0085
0.0093
0.0081
0.0108
0.0081
0.0092
0.0090
0.0092
0.0078
0.0072
0.0085
0.0092
0.0067
0.0975
0.0711
0.0503
0.0429
0.0344
0.0222
0.0169
0.0162
0.0159
0.0108
0.0095
0.0083
0.0069
0.0097
0.0046
0.0041
0.0032
0.0041
0.0012
0.0019
0.0016
0.0016
0.0383
21
0.0314
0.0388
0.0356
0.0300
0.0195
0.0188
0.0171
0.0149
0.0117
0.0095
0.0090
0.0098
0.0073
0.0076
0.0080
0.0083
0.0078
0.0056
0.0054
0.0046
0.0076
0.0066
0.0056
0.0049
0.0051
0.0076
0.0046
0.0061
0.0056
0.0041
0.0078
0.0059
0.0085
0.0085
0.0076
0.0066
0.0063
0.0071
0.0068
0.0054
0.0073
0.0059
0.0046
0.0051
0.0049
0.0773
0.0756
0.0722
0.0573
0.0461
0.0339
0.0258
0.0190
0.0149
0.0122
0.0132
0.0061
0.0066
0.0168
0.0056
0.0063
0.0039
0.0020
0.0027
0.0022
0.0027
0.0010
0.0402
22
0.0364
0.0337
0.0255
0.0271
0.0251
0.0143
0.0139
0.0143
0.0124
0.0093
0.0066
0.0124
0.0074
0.0070
0.0066
0.0058
0.0054
0.0062
0.0062
0.0035
0.0066
0.0031
0.0023
0.0062
0.0054
0.0019
0.0035
0.0035
0.0066
0.0054
0.0077
0.0058
0.0070
0.0050
0.0031
0.0070
0.0074
0.0046
0.0066
0.0074
0.0062
0.0039
0.0058
0.0050
0.0054
0.0758
0.0495
0.0592
0.0592
0.0476
0.0449
0.0433
0.0313
0.0240
0.0190
0.0139
0.0132
0.0174
0.0097
0.0054
0.0066
0.0054
0.0066
0.0062
0.0035
0.0027
0.0015
0.0429
23
0.0284
0.0373
0.0343
0.0355
0.0166
0.0148
0.0154
0.0124
0.0077
0.0089
0.0036
0.0071
0.0083
0.0059
0.0030
0.0041
0.0012
0.0047
0.0065
0.0030
0.0024
0.0024
0.0036
0.0030
0.0036
0.0036
0.0053
0.0024
0.0024
0.0036
0.0083
0.0071
0.0024
0.0036
0.0047
0.0065
0.0059
0.0053
0.0053
0.0053
0.0036
0.0030
0.0047
0.0047
0.0059
0.0580
0.0545
0.0557
0.0438
0.0497
0.0456
0.0420
0.0414
0.0237
0.0237
0.0195
0.0160
0.0136
0.0207
0.0095
0.0112
0.0213
0.0166
0.0095
0.0036
0.0047
0.0071
0.0414
0
0.0295
0.0295
0.0284
0.0197
0.0164
0.0131
0.0098
0.0120
0.0120
0.0066
0.0033
0.0098
0.0077
0.0088
0.0055
0.0088
0.0055
0.0033
0.0011
0.0033
0.0033
0.0022
0.0011
0.0022
0.0000
0.0044
0.0033
0.0022
0.0066
0.0033
0.0120
0.0066
0.0011
0.0000
0.0098
0.0066
0.0044
0.0055
0.0022
0.0044
0.0088
0.0055
0.0077
0.0044
0.0088
0.0624
0.0547
0.0580
0.0624
0.0569
0.0580
0.0306
0.0274
0.0219
0.0492
0.0164
0.0131
0.0131
0.0088
0.0055
0.0098
0.0077
0.0109
0.0131
0.0142
0.0066
0.0088
0.0405
1
0.0420
0.0509
0.0376
0.0221
0.0177
0.0088
0.0221
0.0088
0.0111
0.0177
0.0133
0.0133
0.0088
0.0133
0.0044
0.0044
0.0044
0.0044
0.0044
0.0022
0.0022
0.0022
0.0022
0.0022
0.0044
0.0022
0.0022
0.0022
0.0066
0.0066
0.0177
0.0155
0.0022
0.0111
0.0044
0.0000
0.0111
0.0088
0.0111
0.0066
0.0088
0.0044
0.0066
0.0111
0.0088
0.0597
0.0509
0.0597
0.0420
0.0376
0.0221
0.0332
0.0221
0.0133
0.0221
0.0199
0.0155
0.0066
0.0088
0.0155
0.0044
0.0177
0.0088
0.0066
0.0044
0.0088
0.0066
0.0398
2
0.0381
0.0381
0.0346
0.0346
0.0242
0.0069
0.0208
0.0208
0.0035
0.0035
0.0069
0.0104
0.0000
0.0069
0.0069
0.0000
0.0104
0.0035
0.0104
0.0035
0.0000
0.0000
0.0035
0.0035
0.0000
0.0000
0.0069
0.0000
0.0104
0.0000
0.0138
0.0000
0.0000
0.0000
0.0138
0.0104
0.0069
0.0069
0.0035
0.0035
0.0069
0.0104
0.0000
0.0069
0.0035
0.0484
0.0554
0.0900
0.0727
0.0484
0.0450
0.0311
0.0173
0.0242
0.0138
0.0069
0.0000
0.0138
0.0000
0.0173
0.0173
0.0035
0.0208
0.0069
0.0035
0.0069
0.0035
0.0588
3
0.0476
0.0357
0.0159
0.0079
0.0079
0.0159
0.0198
0.0040
0.0040
0.0119
0.0040
0.0159
0.0000
0.0119
0.0000
0.0040
0.0000
0.0119
0.0040
0.0040
0.0040
0.0079
0.0079
0.0198
0.0000
0.0040
0.0079
0.0079
0.0000
0.0000
0.0000
0.0000
0.0079
0.0079
0.0040
0.0040
0.0000
0.0040
0.0079
0.0000
0.0040
0.0000
0.0119
0.0119
0.0000
0.0397
0.0317
0.0397
0.0357
0.0595
0.0317
0.0635
0.0198
0.0159
0.0238
0.0238
0.0278
0.0198
0.0119
0.0040
0.0079
0.0040
0.0278
0.0040
0.0198
0.0317
0.0079
0.0992
4
0.0445
0.0205
0.0342
0.0205
0.0137
0.0171
0.0034
0.0034
0.0000
0.0068
0.0205
0.0000
0.0103
0.0068
0.0000
0.0068
0.0034
0.0000
0.0034
0.0034
0.0068
0.0000
0.0000
0.0068
0.0034
0.0000
0.0000
0.0000
0.0000
0.0000
0.0034
0.0034
0.0034
0.0000
0.0068
0.0000
0.0000
0.0034
0.0000
0.0068
0.0034
0.0000
0.0000
0.0034
0.0000
0.0240
0.0205
0.0137
0.0240
0.0103
0.0103
0.0103
0.0137
0.0171
0.0171
0.0205
0.0205
0.0274
0.0205
0.0479
0.0308
0.0205
0.0411
0.0137
0.0240
0.0103
0.0342
0.2568
5
0.0196
0.0196
0.0196
0.0157
0.0078
0.0088
0.0049
0.0059
0.0010
0.0020
0.0039
0.0029
0.0010
0.0000
0.0020
0.0010
0.0010
0.0010
0.0010
0.0020
0.0010
0.0010
0.0010
0.0010
0.0010
0.0000
0.0000
0.0020
0.0010
0.0000
0.0010
0.0000
0.0000
0.0010
0.0010
0.0010
0.0020
0.0000
0.0010
0.0000
0.0020
0.0000
0.0000
0.0010
0.0000
0.0029
0.0020
0.0000
0.0010
0.0010
0.0049
0.0010
0.0029
0.0029
0.0039
0.0069
0.0157
0.0147
0.0275
0.0480
0.0363
0.0392
0.0431
0.0441
0.0382
0.0373
0.0284
0.4598
44
-------
Appendix A3: Commute Atlanta Weekday Soak Time Distributions Weighted by Sample
Strata (Household Size, Household Income, and Vehicle Ownership)
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
S 22
O 23
A 24
K 25
C 26
O 27
D 28
E 29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
0.0279
0.0270
0.0251
0.0170
0.0139
0.0086
0.0059
0.0039
0.0028
0.0033
0.0033
0.0028
0.0016
0.0009
0.0014
0.0023
0.0028
0.0024
0.0027
0.0021
0.0026
0.0031
0.0027
0.0033
0.0024
0.0013
0.0012
0.0008
0.0012
0.0007
0.0027
0.0016
0.0016
0.0017
0.0007
0.0013
0.0004
0.0010
0.0010
0.0012
0.0008
0.0010
0.0009
0.0007
0.0009
0.0109
0.0060
0.0061
0.0103
0.0107
0.0041
0.0028
0.0055
0.0078
0.0098
0.0159
0.0148
0.0226
0.0218
0.0196
0.0243
0.0301
0.0381
0.0371
0.0403
0.0461
0.0446
0.3766
7
0.0332
0.0351
0.0271
0.0194
0.0147
0.0113
0.0086
0.0064
0.0052
0.0048
0.0040
0.0028
0.0029
0.0024
0.0025
0.0022
0.0022
0.0017
0.0018
0.0016
0.0016
0.0012
0.0017
0.0015
0.0016
0.0013
0.0014
0.0012
0.0011
0.0012
0.0025
0.0028
0.0020
0.0021
0.0024
0.0017
0.0016
0.0016
0.0021
0.0015
0.0017
0.0019
0.0019
0.0012
0.0022
0.0194
0.0055
0.0036
0.0051
0.0075
0.0076
0.0073
0.0016
0.0038
0.0025
0.0038
0.0071
0.0148
0.0212
0.0203
0.0213
0.0246
0.0335
0.0377
0.0432
0.0428
0.0423
0.3904
8
0.0364
0.0401
0.0360
0.0277
0.0215
0.0166
0.0133
0.0142
0.0107
0.0087
0.0084
0.0073
0.0060
0.0057
0.0054
0.0050
0.0048
0.0051
0.0043
0.0045
0.0033
0.0043
0.0027
0.0036
0.0029
0.0030
0.0034
0.0038
0.0031
0.0032
0.0054
0.0057
0.0051
0.0060
0.0059
0.0054
0.0051
0.0042
0.0046
0.0035
0.0033
0.0035
0.0028
0.0030
0.0031
0.0258
0.0122
0.0104
0.0055
0.0032
0.0047
0.0063
0.0038
0.0028
0.0016
0.0022
0.0029
0.0040
0.0061
0.0125
0.0156
0.0185
0.0213
0.0192
0.0226
0.0278
0.0307
0.3589
9
0.0408
0.0448
0.0435
0.0351
0.0268
0.0229
0.0175
0.0167
0.0136
0.0111
0.0103
0.0092
0.0082
0.0085
0.0057
0.0071
0.0066
0.0074
0.0064
0.0051
0.0048
0.0037
0.0039
0.0044
0.0053
0.0043
0.0043
0.0046
0.0036
0.0029
0.0082
0.0063
0.0062
0.0062
0.0061
0.0045
0.0047
0.0048
0.0051
0.0046
0.0044
0.0045
0.0040
0.0046
0.0046
0.0525
0.0285
0.0160
0.0059
0.0047
0.0034
0.0030
0.0034
0.0042
0.0044
0.0026
0.0015
0.0018
0.0024
0.0032
0.0051
0.0090
0.0130
0.0105
0.0136
0.0126
0.0143
0.3163
10
0.0369
0.0397
0.0437
0.0377
0.0309
0.0259
0.0207
0.0172
0.0163
0.0132
0.0129
0.0110
0.0114
0.0107
0.0104
0.0086
0.0088
0.0079
0.0082
0.0072
0.0080
0.0075
0.0054
0.0063
0.0051
0.0061
0.0053
0.0050
0.0052
0.0047
0.0109
0.0102
0.0094
0.0074
0.0074
0.0073
0.0070
0.0073
0.0073
0.0066
0.0051
0.0053
0.0067
0.0050
0.0057
0.0693
0.0381
0.0263
0.0183
0.0096
0.0054
0.0041
0.0025
0.0029
0.0021
0.0031
0.0030
0.0020
0.0011
0.0008
0.0019
0.0020
0.0046
0.0072
0.0071
0.0093
0.0091
0.2238
11
0.0364
0.0379
0.0382
0.0327
0.0302
0.0264
0.0202
0.0194
0.0164
0.0151
0.0152
0.0124
0.0126
0.0108
0.0109
0.0099
0.0096
0.0086
0.0084
0.0076
0.0074
0.0068
0.0076
0.0063
0.0077
0.0068
0.0065
0.0063
0.0056
0.0050
0.0121
0.0096
0.0103
0.0089
0.0087
0.0073
0.0075
0.0069
0.0066
0.0064
0.0066
0.0058
0.0062
0.0059
0.0064
0.0587
0.0357
0.0320
0.0339
0.0363
0.0324
0.0202
0.0133
0.0096
0.0048
0.0023
0.0019
0.0025
0.0018
0.0010
0.0008
0.0010
0.0010
0.0016
0.0027
0.0037
0.0044
0.1382
MOBILE6.2 HOUR OF DAY
12 13 14
0.0345
0.0381
0.0380
0.0333
0.0276
0.0253
0.0211
0.0186
0.0141
0.0153
0.0130
0.0130
0.0119
0.0117
0.0107
0.0098
0.0094
0.0096
0.0078
0.0085
0.0089
0.0072
0.0075
0.0068
0.0073
0.0068
0.0082
0.0070
0.0059
0.0068
0.0138
0.0137
0.0125
0.0123
0.0106
0.0100
0.0101
0.0093
0.0098
0.0087
0.0079
0.0079
0.0064
0.0054
0.0060
0.0610
0.0321
0.0275
0.0256
0.0270
0.0344
0.0371
0.0234
0.0137
0.0117
0.0057
0.0020
0.0014
0.0016
0.0013
0.0016
0.0012
0.0004
0.0006
0.0006
0.0009
0.0013
0.0998
0.0339
0.0391
0.0386
0.0354
0.0277
0.0239
0.0211
0.0197
0.0182
0.0151
0.0138
0.0117
0.0120
0.0125
0.0114
0.0096
0.0110
0.0096
0.0092
0.0083
0.0091
0.0079
0.0079
0.0085
0.0075
0.0072
0.0069
0.0079
0.0079
0.0074
0.0132
0.0134
0.0131
0.0108
0.0110
0.0113
0.0106
0.0089
0.0103
0.0092
0.0084
0.0080
0.0082
0.0074
0.0069
0.0707
0.0395
0.0255
0.0236
0.0190
0.0173
0.0222
0.0209
0.0166
0.0131
0.0075
0.0033
0.0027
0.0031
0.0029
0.0038
0.0089
0.0015
0.0010
0.0008
0.0009
0.0006
0.0843
0.0353
0.0372
0.0393
0.0345
0.0309
0.0236
0.0219
0.0192
0.0164
0.0169
0.0125
0.0131
0.0119
0.0124
0.0104
0.0104
0.0101
0.0090
0.0087
0.0097
0.0084
0.0090
0.0070
0.0073
0.0067
0.0066
0.0068
0.0065
0.0063
0.0064
0.0100
0.0120
0.0111
0.0098
0.0095
0.0094
0.0094
0.0075
0.0075
0.0083
0.0081
0.0075
0.0069
0.0062
0.0059
0.0695
0.0396
0.0289
0.0243
0.0178
0.0131
0.0151
0.0113
0.0206
0.0129
0.0149
0.0114
0.0144
0.0154
0.0075
0.0118
0.0099
0.0022
0.0014
0.0018
0.0009
0.0009
0.0707
15
0.0388
0.0411
0.0433
0.0363
0.0302
0.0271
0.0228
0.0183
0.0166
0.0149
0.0131
0.0134
0.0109
0.0107
0.0104
0.0107
0.0094
0.0092
0.0093
0.0076
0.0074
0.0081
0.0068
0.0062
0.0067
0.0062
0.0062
0.0059
0.0049
0.0053
0.0092
0.0090
0.0092
0.0079
0.0086
0.0066
0.0075
0.0068
0.0064
0.0067
0.0063
0.0062
0.0059
0.0060
0.0055
0.0617
0.0344
0.0292
0.0262
0.0219
0.0168
0.0144
0.0092
0.0094
0.0126
0.0110
0.0126
0.0121
0.0263
0.0230
0.0276
0.0148
0.0068
0.0025
0.0019
0.0013
0.0012
0.0572
16
0.0329
0.0386
0.0395
0.0350
0.0290
0.0227
0.0207
0.0174
0.0165
0.0151
0.0138
0.0140
0.0115
0.0109
0.0100
0.0088
0.0101
0.0092
0.0080
0.0086
0.0070
0.0075
0.0079
0.0074
0.0063
0.0065
0.0069
0.0053
0.0058
0.0052
0.0101
0.0092
0.0100
0.0083
0.0078
0.0084
0.0077
0.0073
0.0058
0.0064
0.0060
0.0059
0.0051
0.0051
0.0050
0.0612
0.0370
0.0286
0.0242
0.0299
0.0292
0.0228
0.0128
0.0086
0.0078
0.0092
0.0096
0.0117
0.0158
0.0185
0.0345
0.0297
0.0127
0.0093
0.0023
0.0008
0.0007
0.0372
17
0.0346
0.0380
0.0369
0.0345
0.0265
0.0208
0.0200
0.0176
0.0162
0.0153
0.0121
0.0134
0.0111
0.0101
0.0101
0.0098
0.0094
0.0077
0.0083
0.0080
0.0072
0.0062
0.0068
0.0060
0.0065
0.0056
0.0058
0.0054
0.0057
0.0044
0.0093
0.0094
0.0081
0.0083
0.0075
0.0079
0.0076
0.0077
0.0064
0.0063
0.0062
0.0062
0.0059
0.0055
0.0056
0.0633
0.0399
0.0319
0.0238
0.0240
0.0282
0.0329
0.0196
0.0138
0.0086
0.0058
0.0091
0.0093
0.0100
0.0173
0.0239
0.0344
0.0194
0.0130
0.0050
0.0020
0.0011
0.0361
18
0.0340
0.0357
0.0368
0.0294
0.0246
0.0210
0.0197
0.0161
0.0168
0.0153
0.0127
0.0118
0.0104
0.0122
0.0094
0.0106
0.0081
0.0091
0.0092
0.0085
0.0067
0.0078
0.0070
0.0077
0.0060
0.0064
0.0066
0.0060
0.0063
0.0058
0.0115
0.0113
0.0098
0.0101
0.0091
0.0085
0.0086
0.0080
0.0080
0.0077
0.0072
0.0070
0.0067
0.0073
0.0065
0.0769
0.0504
0.0380
0.0294
0.0219
0.0181
0.0176
0.0178
0.0181
0.0123
0.0094
0.0077
0.0078
0.0074
0.0084
0.0103
0.0159
0.0176
0.0136
0.0101
0.0062
0.0030
0.0373
19
0.0326
0.0361
0.0377
0.0289
0.0240
0.0203
0.0198
0.0148
0.0144
0.0157
0.0137
0.0123
0.0102
0.0123
0.0103
0.0080
0.0079
0.0080
0.0077
0.0082
0.0078
0.0076
0.0060
0.0066
0.0066
0.0066
0.0063
0.0063
0.0053
0.0064
0.0128
0.0107
0.0114
0.0100
0.0096
0.0091
0.0092
0.0103
0.0109
0.0113
0.0096
0.0076
0.0087
0.0088
0.0080
0.0959
0.0622
0.0418
0.0314
0.0236
0.0193
0.0138
0.0113
0.0110
0.0116
0.0104
0.0073
0.0052
0.0049
0.0079
0.0071
0.0069
0.0078
0.0100
0.0092
0.0066
0.0049
0.0338
20
0.0357
0.0361
0.0368
0.0308
0.0267
0.0235
0.0166
0.0156
0.0150
0.0134
0.0120
0.0097
0.0099
0.0101
0.0086
0.0099
0.0080
0.0086
0.0075
0.0072
0.0066
0.0068
0.0056
0.0065
0.0059
0.0051
0.0059
0.0046
0.0041
0.0058
0.0094
0.0083
0.0101
0.0082
0.0076
0.0080
0.0080
0.0066
0.0081
0.0079
0.0087
0.0079
0.0083
0.0080
0.0092
0.1130
0.0904
0.0639
0.0433
0.0271
0.0175
0.0138
0.0099
0.0086
0.0066
0.0052
0.0054
0.0040
0.0047
0.0035
0.0030
0.0034
0.0047
0.0062
0.0054
0.0041
0.0032
0.0301
21
0.0361
0.0422
0.0347
0.0266
0.0235
0.0160
0.0162
0.0133
0.0130
0.0130
0.0130
0.0109
0.0082
0.0077
0.0082
0.0070
0.0061
0.0053
0.0055
0.0067
0.0045
0.0058
0.0054
0.0043
0.0043
0.0058
0.0053
0.0039
0.0029
0.0038
0.0099
0.0061
0.0078
0.0066
0.0067
0.0072
0.0059
0.0072
0.0077
0.0058
0.0068
0.0081
0.0062
0.0054
0.0054
0.0824
0.0794
0.0901
0.0685
0.0432
0.0317
0.0233
0.0153
0.0132
0.0103
0.0094
0.0054
0.0068
0.0044
0.0038
0.0051
0.0034
0.0022
0.0025
0.0025
0.0023
0.0029
0.0301
22
0.0270
0.0348
0.0269
0.0216
0.0163
0.0120
0.0121
0.0093
0.0076
0.0072
0.0081
0.0051
0.0059
0.0071
0.0056
0.0058
0.0042
0.0040
0.0041
0.0047
0.0035
0.0041
0.0028
0.0035
0.0039
0.0030
0.0030
0.0029
0.0018
0.0017
0.0059
0.0041
0.0056
0.0061
0.0038
0.0062
0.0064
0.0036
0.0043
0.0047
0.0048
0.0047
0.0049
0.0058
0.0060
0.0669
0.0650
0.0572
0.0588
0.0614
0.0496
0.0393
0.0309
0.0224
0.0205
0.0203
0.0168
0.0127
0.0123
0.0090
0.0067
0.0091
0.0082
0.0065
0.0046
0.0041
0.0047
0.0766
23
0.0236
0.0223
0.0167
0.0160
0.0110
0.0088
0.0061
0.0068
0.0054
0.0044
0.0041
0.0056
0.0039
0.0042
0.0027
0.0030
0.0035
0.0039
0.0026
0.0040
0.0038
0.0028
0.0030
0.0015
0.0022
0.0024
0.0025
0.0017
0.0019
0.0023
0.0035
0.0035
0.0024
0.0035
0.0045
0.0021
0.0067
0.0041
0.0034
0.0036
0.0046
0.0034
0.0032
0.0033
0.0029
0.0499
0.0591
0.0490
0.0445
0.0465
0.0478
0.0518
0.0414
0.0344
0.0244
0.0298
0.0229
0.0203
0.0178
0.0202
0.0273
0.0133
0.0073
0.0063
0.0071
0.0080
0.0060
0.1274
0
0.0321
0.0230
0.0253
0.0181
0.0129
0.0086
0.0075
0.0029
0.0092
0.0038
0.0034
0.0040
0.0071
0.0045
0.0057
0.0027
0.0029
0.0009
0.0043
0.0032
0.0035
0.0025
0.0031
0.0015
0.0052
0.0039
0.0038
0.0014
0.0027
0.0020
0.0045
0.0063
0.0065
0.0034
0.0044
0.0040
0.0027
0.0044
0.0057
0.0052
0.0021
0.0062
0.0067
0.0047
0.0052
0.0514
0.0399
0.0546
0.0542
0.0479
0.0484
0.0396
0.0294
0.0354
0.0505
0.0234
0.0259
0.0176
0.0169
0.0215
0.0197
0.0111
0.0092
0.0090
0.0098
0.0034
0.0076
0.0902
1
0.0405
0.0225
0.0161
0.0181
0.0170
0.0122
0.0113
0.0076
0.0082
0.0032
0.0041
0.0034
0.0028
0.0119
0.0046
0.0031
0.0019
0.0094
0.0063
0.0023
0.0045
0.0055
0.0059
0.0030
0.0020
0.0041
0.0060
0.0032
0.0000
0.0005
0.0055
0.0060
0.0042
0.0021
0.0075
0.0024
0.0033
0.0033
0.0062
0.0058
0.0017
0.0038
0.0076
0.0017
0.0011
0.0474
0.0663
0.0669
0.0476
0.0427
0.0583
0.0329
0.0141
0.0320
0.0213
0.0252
0.0255
0.0224
0.0214
0.0211
0.0156
0.0174
0.0160
0.0110
0.0102
0.0064
0.0029
0.0716
2
0.0327
0.0211
0.0279
0.0184
0.0196
0.0106
0.0089
0.0097
0.0115
0.0076
0.0024
0.0058
0.0048
0.0016
0.0024
0.0053
0.0000
0.0038
0.0007
0.0039
0.0000
0.0008
0.0047
0.0008
0.0035
0.0000
0.0008
0.0005
0.0013
0.0035
0.0000
0.0038
0.0013
0.0092
0.0046
0.0020
0.0030
0.0032
0.0000
0.0017
0.0020
0.0068
0.0016
0.0055
0.0079
0.0302
0.0406
0.0399
0.0375
0.0444
0.0422
0.0414
0.0660
0.0483
0.0236
0.0414
0.0320
0.0326
0.0145
0.0225
0.0157
0.0102
0.0136
0.0170
0.0150
0.0025
0.0104
0.0916
3
0.0134
0.0068
0.0104
0.0080
0.0023
0.0015
0.0028
0.0020
0.0024
0.0008
0.0008
0.0007
0.0016
0.0008
0.0020
0.0009
0.0010
0.0017
0.0029
0.0004
0.0028
0.0003
0.0012
0.0010
0.0017
0.0005
0.0000
0.0000
0.0003
0.0010
0.0007
0.0000
0.0008
0.0003
0.0015
0.0003
0.0002
0.0002
0.0002
0.0022
0.0034
0.0002
0.0002
0.0007
0.0010
0.0094
0.0096
0.0112
0.0134
0.0208
0.0620
0.0470
0.0539
0.0376
0.0242
0.0322
0.0338
0.0369
0.0400
0.0356
0.0339
0.0333
0.0355
0.0361
0.0294
0.0264
0.0273
0.2265
4
0.0089
0.0107
0.0043
0.0045
0.0016
0.0015
0.0003
0.0039
0.0022
0.0016
0.0061
0.0006
0.0015
0.0012
0.0024
0.0014
0.0006
0.0000
0.0008
0.0008
0.0005
0.0000
0.0000
0.0005
0.0023
0.0000
0.0003
0.0002
0.0013
0.0005
0.0006
0.0005
0.0011
0.0002
0.0005
0.0023
0.0013
0.0000
0.0011
0.0000
0.0008
0.0021
0.0007
0.0000
0.0002
0.0087
0.0073
0.0097
0.0079
0.0057
0.0127
0.0466
0.0878
0.0476
0.0316
0.0331
0.0343
0.0333
0.0288
0.0271
0.0349
0.0276
0.0311
0.0308
0.0318
0.0339
0.0300
0.2853
5
0.0164
0.0186
0.0142
0.0097
0.0075
0.0032
0.0030
0.0036
0.0022
0.0014
0.0013
0.0011
0.0011
0.0003
0.0010
0.0012
0.0007
0.0013
0.0005
0.0014
0.0005
0.0008
0.0009
0.0007
0.0011
0.0012
0.0009
0.0001
0.0011
0.0006
0.0008
0.0003
0.0008
0.0002
0.0003
0.0012
0.0005
0.0004
0.0004
0.0004
0.0001
0.0008
0.0004
0.0007
0.0003
0.0138
0.0099
0.0069
0.0024
0.0049
0.0083
0.0037
0.0101
0.0197
0.0241
0.0465
0.0200
0.0180
0.0231
0.0296
0.0324
0.0346
0.0464
0.0475
0.0579
0.0467
0.0585
0.3300
45
-------
Appendix A4: Commute Atlanta Weekend Soak Time Distributions Weighted by Sample
Strata (Household Size, Household Income, and Vehicle Ownership)
6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
S 22
O 23
A 24
K 25
C 26
O 27
D 28
E 29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
0.0319
0.0444
0.0363
0.0206
0.0190
0.0125
0.0104
0.0065
0.0057
0.0045
0.0042
0.0059
0.0042
0.0012
0.0020
0.0004
0.0028
0.0011
0.0035
0.0004
0.0063
0.0035
0.0020
0.0004
0.0029
0.0020
0.0053
0.0017
0.0006
0.0011
0.0018
0.0005
0.0011
0.0044
0.0010
0.0023
0.0000
0.0000
0.0033
0.0000
0.0004
0.0000
0.0000
0.0000
0.0005
0.0067
0.0043
0.0036
0.0075
0.0109
0.0054
0.0038
0.0058
0.0090
0.0079
0.0256
0.0186
0.0265
0.0269
0.0351
0.0352
0.0256
0.0289
0.0363
0.0374
0.0375
0.0220
0.3206
7
0.0369
0.0334
0.0323
0.0275
0.0159
0.0111
0.0111
0.0069
0.0071
0.0071
0.0058
0.0054
0.0051
0.0030
0.0043
0.0047
0.0020
0.0037
0.0032
0.0042
0.0022
0.0042
0.0031
0.0054
0.0031
0.0031
0.0043
0.0020
0.0020
0.0037
0.0049
0.0061
0.0023
0.0015
0.0012
0.0054
0.0028
0.0014
0.0034
0.0004
0.0030
0.0021
0.0049
0.0010
0.0010
0.0145
0.0050
0.0032
0.0079
0.0068
0.0129
0.0045
0.0020
0.0017
0.0005
0.0050
0.0110
0.0105
0.0202
0.0318
0.0364
0.0319
0.0296
0.0397
0.0320
0.0232
0.0393
0.3250
8
0.0283
0.0354
0.0338
0.0261
0.0218
0.0190
0.0130
0.0093
0.0088
0.0084
0.0057
0.0040
0.0056
0.0061
0.0038
0.0051
0.0047
0.0034
0.0042
0.0040
0.0037
0.0031
0.0047
0.0034
0.0040
0.0022
0.0029
0.0020
0.0022
0.0019
0.0038
0.0051
0.0051
0.0049
0.0044
0.0026
0.0032
0.0046
0.0030
0.0021
0.0034
0.0023
0.0026
0.0027
0.0018
0.0217
0.0103
0.0088
0.0088
0.0032
0.0123
0.0209
0.0180
0.0021
0.0024
0.0027
0.0025
0.0044
0.0082
0.0125
0.0182
0.0242
0.0264
0.0302
0.0233
0.0267
0.0292
0.3508
9
0.0292
0.0318
0.0372
0.0295
0.0250
0.0167
0.0137
0.0153
0.0116
0.0106
0.0087
0.0081
0.0076
0.0069
0.0065
0.0069
0.0052
0.0065
0.0036
0.0046
0.0040
0.0038
0.0042
0.0039
0.0039
0.0064
0.0038
0.0041
0.0045
0.0050
0.0072
0.0055
0.0063
0.0071
0.0040
0.0051
0.0049
0.0051
0.0033
0.0032
0.0034
0.0040
0.0032
0.0032
0.0038
0.0451
0.0185
0.0070
0.0078
0.0090
0.0073
0.0046
0.0035
0.0025
0.0051
0.0026
0.0011
0.0019
0.0038
0.0039
0.0058
0.0087
0.0152
0.0144
0.0199
0.0186
0.0196
0.3758
10
0.0371
0.0380
0.0357
0.0292
0.0251
0.0193
0.0169
0.0177
0.0143
0.0143
0.0108
0.0124
0.0115
0.0070
0.0087
0.0077
0.0076
0.0061
0.0080
0.0071
0.0058
0.0055
0.0061
0.0053
0.0054
0.0060
0.0048
0.0053
0.0049
0.0050
0.0117
0.0098
0.0094
0.0057
0.0069
0.0065
0.0054
0.0065
0.0069
0.0053
0.0040
0.0049
0.0055
0.0038
0.0046
0.0634
0.0386
0.0234
0.0160
0.0090
0.0031
0.0019
0.0009
0.0018
0.0048
0.0023
0.0017
0.0010
0.0023
0.0022
0.0026
0.0038
0.0043
0.0084
0.0131
0.0128
0.0156
0.2813
11
0.0347
0.0383
0.0446
0.0365
0.0245
0.0190
0.0189
0.0174
0.0155
0.0163
0.0136
0.0149
0.0111
0.0110
0.0096
0.0103
0.0099
0.0084
0.0078
0.0080
0.0071
0.0080
0.0075
0.0069
0.0054
0.0059
0.0052
0.0062
0.0050
0.0056
0.0089
0.0096
0.0088
0.0085
0.0092
0.0081
0.0072
0.0090
0.0057
0.0066
0.0076
0.0056
0.0055
0.0058
0.0049
0.0715
0.0493
0.0313
0.0242
0.0129
0.0055
0.0038
0.0025
0.0012
0.0013
0.0009
0.0012
0.0028
0.0013
0.0008
0.0015
0.0019
0.0024
0.0034
0.0030
0.0053
0.0093
0.2183
MOBILES
0.0310
0.0351
0.0381
0.0338
0.0269
0.0197
0.0175
0.0167
0.0146
0.0130
0.0110
0.0123
0.0128
0.0121
0.0114
0.0132
0.0113
0.0092
0.0094
0.0067
0.0078
0.0067
0.0072
0.0086
0.0083
0.0076
0.0056
0.0062
0.0065
0.0057
0.0130
0.0115
0.0114
0.0105
0.0085
0.0076
0.0090
0.0068
0.0076
0.0073
0.0062
0.0083
0.0047
0.0061
0.0064
0.0842
0.0533
0.0385
0.0381
0.0235
0.0134
0.0099
0.0053
0.0044
0.0018
0.0007
0.0006
0.0005
0.0007
0.0016
0.0012
0.0015
0.0010
0.0020
0.0010
0.0031
0.0042
0.1585
.2 HOUR OF DAY
0.0351
0.0358
0.0380
0.0289
0.0247
0.0197
0.0175
0.0182
0.0170
0.0171
0.0139
0.0119
0.0128
0.0123
0.0113
0.0116
0.0103
0.0093
0.0085
0.0092
0.0093
0.0062
0.0074
0.0095
0.0073
0.0070
0.0091
0.0063
0.0065
0.0067
0.0132
0.0145
0.0137
0.0116
0.0103
0.0123
0.0097
0.0107
0.0095
0.0092
0.0111
0.0075
0.0098
0.0069
0.0074
0.0792
0.0387
0.0374
0.0311
0.0175
0.0147
0.0104
0.0092
0.0074
0.0033
0.0025
0.0022
0.0014
0.0004
0.0008
0.0013
0.0043
0.0006
0.0006
0.0012
0.0020
0.0016
0.1364
0.0325
0.0409
0.0376
0.0354
0.0292
0.0241
0.0217
0.0182
0.0153
0.0180
0.0157
0.0146
0.0117
0.0111
0.0113
0.0109
0.0114
0.0111
0.0115
0.0097
0.0096
0.0082
0.0070
0.0075
0.0073
0.0087
0.0072
0.0081
0.0078
0.0066
0.0112
0.0119
0.0109
0.0111
0.0125
0.0107
0.0080
0.0095
0.0093
0.0088
0.0078
0.0067
0.0075
0.0061
0.0090
0.0811
0.0525
0.0346
0.0237
0.0204
0.0149
0.0092
0.0084
0.0085
0.0058
0.0056
0.0031
0.0031
0.0014
0.0006
0.0005
0.0007
0.0006
0.0007
0.0006
0.0010
0.0010
0.1109
0.0310
0.0389
0.0384
0.0339
0.0258
0.0230
0.0234
0.0189
0.0148
0.0148
0.0151
0.0135
0.0130
0.0144
0.0116
0.0104
0.0103
0.0091
0.0103
0.0089
0.0094
0.0083
0.0078
0.0085
0.0076
0.0078
0.0060
0.0085
0.0077
0.0061
0.0129
0.0130
0.0141
0.0094
0.0111
0.0112
0.0097
0.0074
0.0072
0.0092
0.0088
0.0074
0.0065
0.0063
0.0067
0.0745
0.0497
0.0454
0.0303
0.0261
0.0179
0.0144
0.0123
0.0064
0.0055
0.0059
0.0056
0.0035
0.0027
0.0026
0.0024
0.0008
0.0001
0.0005
0.0007
0.0007
0.0004
0.0934
0.0340
0.0434
0.0396
0.0322
0.0265
0.0215
0.0238
0.0189
0.0176
0.0183
0.0134
0.0130
0.0122
0.0123
0.0120
0.0114
0.0100
0.0079
0.0092
0.0085
0.0097
0.0094
0.0091
0.0086
0.0082
0.0072
0.0068
0.0056
0.0084
0.0050
0.0130
0.0147
0.0111
0.0089
0.0082
0.0093
0.0086
0.0094
0.0084
0.0077
0.0071
0.0077
0.0060
0.0073
0.0055
0.0679
0.0513
0.0374
0.0304
0.0260
0.0203
0.0211
0.0130
0.0084
0.0092
0.0066
0.0072
0.0046
0.0049
0.0035
0.0020
0.0036
0.0012
0.0004
0.0003
0.0000
0.0006
0.0836
0.0346
0.0341
0.0371
0.0308
0.0281
0.0262
0.0184
0.0149
0.0116
0.0151
0.0139
0.0120
0.0141
0.0114
0.0111
0.0098
0.0087
0.0124
0.0082
0.0083
0.0094
0.0109
0.0091
0.0069
0.0072
0.0076
0.0070
0.0080
0.0070
0.0075
0.0129
0.0090
0.0103
0.0130
0.0128
0.0090
0.0070
0.0094
0.0087
0.0085
0.0085
0.0072
0.0074
0.0054
0.0059
0.0804
0.0496
0.0359
0.0305
0.0282
0.0193
0.0232
0.0178
0.0139
0.0106
0.0076
0.0094
0.0039
0.0061
0.0065
0.0033
0.0037
0.0019
0.0010
0.0008
0.0006
0.0002
0.0692
18
0.0325
0.0323
0.0340
0.0312
0.0287
0.0223
0.0189
0.0138
0.0145
0.0131
0.0157
0.0117
0.0114
0.0071
0.0101
0.0099
0.0106
0.0077
0.0091
0.0079
0.0074
0.0089
0.0071
0.0062
0.0063
0.0069
0.0070
0.0063
0.0068
0.0055
0.0087
0.0121
0.0082
0.0091
0.0098
0.0086
0.0101
0.0086
0.0095
0.0080
0.0076
0.0078
0.0082
0.0080
0.0075
0.0921
0.0522
0.0422
0.0354
0.0255
0.0206
0.0207
0.0180
0.0168
0.0147
0.0116
0.0128
0.0081
0.0064
0.0043
0.0056
0.0039
0.0034
0.0031
0.0012
0.0004
0.0005
0.0577
19
0.0344
0.0342
0.0372
0.0268
0.0263
0.0211
0.0191
0.0155
0.0166
0.0140
0.0163
0.0095
0.0118
0.0067
0.0101
0.0089
0.0083
0.0080
0.0087
0.0071
0.0086
0.0065
0.0048
0.0071
0.0064
0.0065
0.0070
0.0055
0.0058
0.0072
0.0093
0.0105
0.0118
0.0085
0.0100
0.0090
0.0090
0.0081
0.0098
0.0071
0.0082
0.0077
0.0079
0.0068
0.0062
0.0978
0.0667
0.0446
0.0351
0.0293
0.0185
0.0202
0.0199
0.0152
0.0141
0.0098
0.0083
0.0063
0.0057
0.0065
0.0031
0.0038
0.0029
0.0024
0.0024
0.0014
0.0007
0.0494
20
0.0372
0.0388
0.0358
0.0278
0.0212
0.0235
0.0180
0.0146
0.0146
0.0141
0.0146
0.0084
0.0120
0.0103
0.0107
0.0099
0.0092
0.0091
0.0076
0.0083
0.0068
0.0079
0.0063
0.0101
0.0038
0.0068
0.0034
0.0051
0.0034
0.0054
0.0085
0.0080
0.0094
0.0097
0.0067
0.0101
0.0070
0.0092
0.0087
0.0097
0.0070
0.0076
0.0087
0.0090
0.0074
0.0962
0.0687
0.0491
0.0381
0.0349
0.0239
0.0192
0.0158
0.0165
0.0115
0.0094
0.0077
0.0068
0.0083
0.0039
0.0033
0.0023
0.0045
0.0012
0.0013
0.0018
0.0018
0.0424
21
0.0307
0.0427
0.0365
0.0289
0.0208
0.0201
0.0165
0.0138
0.0130
0.0081
0.0095
0.0111
0.0064
0.0079
0.0068
0.0079
0.0078
0.0054
0.0048
0.0058
0.0062
0.0059
0.0060
0.0050
0.0043
0.0065
0.0040
0.0064
0.0059
0.0047
0.0070
0.0049
0.0089
0.0079
0.0097
0.0071
0.0072
0.0065
0.0069
0.0048
0.0054
0.0065
0.0048
0.0050
0.0032
0.0742
0.0767
0.0726
0.0573
0.0426
0.0338
0.0252
0.0218
0.0154
0.0128
0.0125
0.0073
0.0088
0.0111
0.0044
0.0075
0.0054
0.0027
0.0031
0.0026
0.0024
0.0013
0.0435
22
0.0431
0.0352
0.0244
0.0295
0.0253
0.0148
0.0156
0.0159
0.0137
0.0086
0.0054
0.0150
0.0062
0.0079
0.0066
0.0071
0.0046
0.0064
0.0063
0.0032
0.0096
0.0021
0.0022
0.0057
0.0072
0.0017
0.0044
0.0036
0.0047
0.0052
0.0073
0.0069
0.0060
0.0031
0.0039
0.0051
0.0062
0.0065
0.0054
0.0067
0.0083
0.0031
0.0051
0.0057
0.0059
0.0690
0.0491
0.0634
0.0504
0.0431
0.0435
0.0367
0.0311
0.0276
0.0192
0.0164
0.0126
0.0173
0.0095
0.0052
0.0097
0.0055
0.0050
0.0089
0.0039
0.0036
0.0010
0.0417
23
0.0295
0.0443
0.0301
0.0321
0.0156
0.0151
0.0150
0.0157
0.0123
0.0104
0.0040
0.0104
0.0124
0.0037
0.0037
0.0044
0.0008
0.0042
0.0077
0.0020
0.0033
0.0025
0.0036
0.0044
0.0048
0.0042
0.0043
0.0021
0.0028
0.0044
0.0080
0.0066
0.0026
0.0040
0.0040
0.0069
0.0041
0.0057
0.0065
0.0048
0.0027
0.0043
0.0061
0.0067
0.0073
0.0602
0.0544
0.0493
0.0362
0.0444
0.0474
0.0405
0.0351
0.0216
0.0251
0.0169
0.0198
0.0139
0.0195
0.0130
0.0111
0.0169
0.0146
0.0068
0.0040
0.0050
0.0066
0.0479
0
0.0298
0.0315
0.0284
0.0192
0.0161
0.0167
0.0093
0.0134
0.0105
0.0066
0.0017
0.0088
0.0041
0.0137
0.0072
0.0074
0.0043
0.0020
0.0019
0.0047
0.0034
0.0015
0.0016
0.0027
0.0000
0.0050
0.0039
0.0023
0.0035
0.0019
0.0144
0.0055
0.0008
0.0000
0.0060
0.0092
0.0034
0.0045
0.0011
0.0055
0.0086
0.0031
0.0081
0.0041
0.0088
0.0528
0.0646
0.0678
0.0683
0.0530
0.0615
0.0374
0.0252
0.0223
0.0397
0.0206
0.0141
0.0138
0.0111
0.0056
0.0106
0.0122
0.0071
0.0091
0.0098
0.0044
0.0055
0.0374
1
0.0564
0.0439
0.0346
0.0189
0.0254
0.0070
0.0292
0.0094
0.0075
0.0177
0.0156
0.0072
0.0060
0.0130
0.0022
0.0040
0.0030
0.0028
0.0070
0.0010
0.0013
0.0010
0.0015
0.0015
0.0028
0.0010
0.0030
0.0015
0.0069
0.0081
0.0198
0.0187
0.0015
0.0072
0.0068
0.0000
0.0068
0.0098
0.0108
0.0035
0.0075
0.0028
0.0035
0.0073
0.0102
0.0658
0.0614
0.0606
0.0506
0.0372
0.0234
0.0488
0.0174
0.0124
0.0209
0.0196
0.0087
0.0040
0.0101
0.0162
0.0070
0.0115
0.0042
0.0103
0.0030
0.0061
0.0035
0.0408
2
0.0411
0.0254
0.0407
0.0372
0.0239
0.0038
0.0392
0.0176
0.0022
0.0022
0.0105
0.0079
0.0000
0.0037
0.0105
0.0000
0.0095
0.0022
0.0123
0.0022
0.0000
0.0000
0.0086
0.0086
0.0000
0.0000
0.0045
0.0000
0.0126
0.0000
0.0208
0.0000
0.0000
0.0000
0.0220
0.0130
0.0045
0.0105
0.0022
0.0015
0.0068
0.0060
0.0000
0.0072
0.0015
0.0445
0.0419
0.0855
0.0511
0.0428
0.0536
0.0365
0.0163
0.0237
0.0067
0.0076
0.0000
0.0169
0.0000
0.0097
0.0112
0.0053
0.0270
0.0037
0.0019
0.0045
0.0092
0.0779
3
0.0525
0.0355
0.0088
0.0123
0.0123
0.0157
0.0193
0.0031
0.0026
0.0149
0.0022
0.0171
0.0000
0.0066
0.0000
0.0022
0.0000
0.0079
0.0022
0.0017
0.0026
0.0048
0.0128
0.0202
0.0000
0.0026
0.0039
0.0118
0.0000
0.0000
0.0000
0.0000
0.0052
0.0130
0.0026
0.0108
0.0000
0.0017
0.0123
0.0000
0.0101
0.0000
0.0061
0.0144
0.0000
0.0385
0.0234
0.0441
0.0258
0.0491
0.0236
0.0413
0.0122
0.0096
0.0289
0.0216
0.0376
0.0202
0.0075
0.0026
0.0118
0.0022
0.0562
0.0017
0.0276
0.0431
0.0075
0.1120
4
0.0472
0.0152
0.0298
0.0177
0.0147
0.0180
0.0016
0.0025
0.0000
0.0040
0.0109
0.0000
0.0144
0.0037
0.0000
0.0119
0.0024
0.0000
0.0021
0.0016
0.0037
0.0000
0.0000
0.0119
0.0016
0.0000
0.0000
0.0000
0.0000
0.0000
0.0094
0.0024
0.0021
0.0000
0.0119
0.0000
0.0000
0.0094
0.0000
0.0066
0.0016
0.0000
0.0000
0.0021
0.0000
0.0237
0.0155
0.0078
0.0275
0.0086
0.0090
0.0069
0.0182
0.0178
0.0205
0.0205
0.0189
0.0271
0.0220
0.0410
0.0300
0.0152
0.0367
0.0090
0.0189
0.0175
0.0552
0.2723
5
0.0186
0.0181
0.0188
0.0227
0.0079
0.0094
0.0077
0.0105
0.0006
0.0026
0.0049
0.0041
0.0006
0.0000
0.0026
0.0018
0.0009
0.0007
0.0006
0.0015
0.0021
0.0006
0.0018
0.0010
0.0006
0.0000
0.0000
0.0026
0.0006
0.0000
0.0033
0.0000
0.0000
0.0033
0.0009
0.0033
0.0023
0.0000
0.0009
0.0000
0.0017
0.0000
0.0000
0.0009
0.0000
0.0020
0.0015
0.0000
0.0018
0.0021
0.0035
0.0007
0.0017
0.0045
0.0030
0.0054
0.0160
0.0139
0.0280
0.0321
0.0281
0.0383
0.0420
0.0376
0.0301
0.0386
0.0243
0.4846
46
-------
Appendix B: Commute Atlanta Engine Start Time Distributions
Hour
Actual Hours
Commute Atlanta
Weighted
Commute Atlanta
Weekday
Weekend
Weekday
Weekend
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
0
1
2
O
4
5
06:00
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
24:00
01:00
02:00
03:00
04:00
05:00
0.029849
0.051204
0.047942
0.049401
0.053386
0.065006
0.074324
0.067611
0.067956
0.071843
0.078472
0.077938
0.070553
0.053573
0.04219
0.027818
0.01962
0.016342
0.006019
0.00305
0.001968
0.006612
0.006024
0.0113
0.009031
0.019971
0.044756
0.061087
0.072213
0.077888
0.096156
0.08692
0.081577
0.079943
0.078847
0.072996
0.063005
0.051831
0.035265
0.02457
0.014609
0.008513
0.004707
0.001996
0.001311
0.001487
0.002045
0.009276
0.027345
0.048600
0.050070
0.048261
0.051706
0.062166
0.072485
0.066832
0.067509
0.075297
0.077637
0.078203
0.071226
0.054206
0.042810
0.029292
0.020948
0.017813
0.007042
0.003502
0.002335
0.007245
0.006133
0.011336
0.009019
0.018141
0.041503
0.057981
0.070145
0.078169
0.089239
0.084535
0.080641
0.081039
0.079463
0.072323
0.064334
0.052036
0.038207
0.028809
0.018118
0.012908
0.006722
0.003576
0.002425
0.002111
0.002236
0.00632
47
-------
Appendix C: MOBILE6.2 Control Files
48
-------
Appendix Cl: Mobile6.2 Control File for the 13-County Atlanta Metropolitan Area, GA
MOBILE6 INPUT FILE
DAILY OUTPUT
NO DESC OUTPUT
DATABASE EMISSIONS
DATABASE FACILITIES
DATABASE OUTPUT
DATABASE VEHICLES
POLLUTANTS
WITH FIELDNAMES
2222 2221 11
NONE
22222 11111111 1 111 11111111 111
HC CO NOX
RUN DATA
HOURLY TEMPERATURES
FUEL RVP
EXPRESS HC AS VOC
EXPAND EXHAUST
EXPAND EVAPORATIVE
EXPAND LOT EFS
STAGE II REFUELING
92 3 81. 81.
74 74 74
89 (.
7.0
84
92 92 92 94 94 94
89 81 81 81 75 75 75 72 72 72
FUEL PROGRAM
: 4
150.0 150.0 150.0 90.0
30.0 30.0 30.0 30.0
1000.0 1000.0 1000.0 1000.0
80.0 80.0 80.0 80.0
30.0 30.0 30.0 30.0
30.0 30.0 30.0 30.0
150.0 150.0 87.0 87.0
80.0 80.0 80.0 80.0
REG DIST
: 02regis2.d
ANTI-TAMP PROG :
82 75 97 22222 11111111 1 11 097. 12111111
I/M DESCRIPT FILE
I/M CREDIT FILE
STARTS PER DAY
START DIST
SCENARIO REC
SOAK DISTRIBUTION
CALENDAR YEAR
EVALUATION MONTH
ALTITUDE
RELATIVE HUMIDITY
BAROMETRIC PRES
iminfo-p.d
Techl2.d
ASTPERD.D
ASDIST.D
Georgia, 13-county Atlanta Region
ASOAK.D
2005
7
1
68 68 68 50 50 50 37 37 37 32 32 32
40 40 40 56 56 56 64 64 64 70 70 70
28.98
END OF RUN
49
-------
Appendix C2: Mobile6.2 Control File for Gaston County, NC
MOBILE6 INPUT FILE
DAILY OUTPUT
NO DESC OUTPUT
DATABASE EMISSIONS
DATABASE FACILITIES
DATABASE OUTPUT
DATABASE VEHICLES
POLLUTANTS
WITH FIELDNAMES
RUN DATA
HOURLY TEMPERATURES
91.5
69.7
FUEL RVP
EXPRESS HC AS VOC :
EXPAND EXHAUST :
EXPAND EVAPORATIVE :
EXPAND LOT EFS :
FUEL PROGRAM : 4
239.6 239.6 239.6 239.6 239.6 239.6 239.6 239.6
239.6 239.6 239.6 239.6 239.6 239.6 239.6 239.6
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
ANTI-TAMP PROG :
92 68 50 22222 22222222 2 11 096. 22212222
2222 2221 11
NONE
22222 11111111 1 111 11111111 111
HC CO NOX
69.7 72.9 76.9 81.0 84.4 87.5 89.9 91.3 92.1 92.5 92.3
88.9 85.4 81.5 79.4 77.5 76.0 74.3 73.3 72.2 71.1 70.2
7.4
I/M DESC FILE
SCENARIO REC
CALENDAR YEAR
EVALUATION MONTH
ALTITUDE
RELATIVE HUMIDITY
49.3
89.6
BAROMETRIC PRES
END OF RUN
3705792.imp
North Carolina, Gaston (071) County
2005
7
1
90.2 85.2 78.0 70.5 64.3 58.8 54.1 51.3 49.5 48.7 48.9
52.9 58.7 65.4 69.8 73.1 76.6 80.7 82.4 85.2 87.5 88.7
29.0
50
-------
Appendix C3: Mobile6.2 Control File for Mecklenburg County, NC
MOBILE6 INPUT FILE
DAILY OUTPUT :
NO DESC OUTPUT :
DATABASE EMISSIONS : 2222 2221 11
DATABASE FACILITIES: NONE
DATABASE OUTPUT :
DATABASE VEHICLES : 22222 11111111 1 111 11111111 111
POLLUTANTS : HC CO NOX
WITH FIELDNAMES :
RUN DATA :
HOURLY TEMPERATURES: 69.6 72.9 76.9 80.8 84.2 87.3 89.4 90.9 91.5 92.0 91.8 90.9
88.4 85.3 81.4 79.2 77.6 76.1 74.4 73.1 72.2 71.1 70.2 69.5
FUELRVP :7.4
EXPRESS HC AS VOC :
EXPAND EXHAUST :
EXPAND EVAPORATIVE :
EXPAND LOT EPS :
FUELPROGRAM :4
239.6 239.6 239.6 239.6 239.6 239.6 239.6 239.6
239.6 239.6 239.6 239.6 239.6 239.6 239.6 239.6
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
ANTI-TAMPPROG :
83 68 50 22222 22222222 2 11 096. 22212222
I/M DESC FILE : 3711983.imp
SCENARIO REC : North Carolina, Mecklenburg (119) County
CALENDAR YEAR : 2005
EVALUATION MONTH :7
ALTITUDE : 1
RELATIVE HUMIDITY : 89.9 84.6 76.9 69.3 62.7 57.4 52.6 49.9 48.6 47.5 47.5 48.2
51.4 56.1 63.4 68.4 71.6 75.5 79.9 82.3 84.9 86.9 88.4 89.9
BAROMETRIC PRES : 29.2
END OF RUN
51
-------
Appendix C4: Mobile6.2 Control File for York County, SC
MOBILE6 INPUT FILE
DAILY OUTPUT
NO DESC OUTPUT
DATABASE EMISSIONS
DATABASE FACILITIES
DATABASE OUTPUT
DATABASE VEHICLES
POLLUTANTS
WITH FIELDNAMES
2222 2221 11
NONE
22222 11111111 1 111 11111111 111
HC CO NOX
RUN DATA
HOURLY TEMPERATURES: 70.1 73.4 77.5 81.7 85.3 88.2 90.5 91.9 92.9 93.0 92.9
92.2
89.6 86.0 82.0 79.7 78.0 76.5 74.7 73.6 72.4 71.3 70.6
70.0
FUEL RVP : 7.4
EXPRESS HC AS VOC :
EXPAND EXHAUST :
EXPAND EVAPORATIVE :
EXPAND LOT EFS :
FUEL PROGRAM : 4
242.3 242.3 242.3 242.3 242.3 242.3 242.3 242.3
242.3 242.3 242.3 242.3 242.3 242.3 242.3 242.3
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0
SCENARIO REC
CALENDAR YEAR
EVALUATION MONTH
ALTITUDE
RELATIVE HUMIDITY
48.0
90.5
BAROMETRIC PRES
South Carolina, York (091) County
2005
7
1
90.5 85.8 78.0 69.9 63.1 57.7 53.3 50.2 48.1 47.8 47.7
51.4 58.0 65.1 70.1 73.1 76.3 81.1 83.5 86.4
29.2
.4 89.3
END OF RUN
52
-------
References
ARC (2002). Transportation Solutions for a New Century Appendix 4: Model Documen-
tation. Atlanta Regional Commission.
GDNR, Georgia Department of Natural Resources (2005). Existing State Implementation
Plans. Georgia Department of Natural Resources (See http://www.dnr.state.ga.us/dnr/en-
viron/, Accessed November 2005).
Guensler, R., S. Yoon, H. Li, V. Elango, J. Ogle, and M. Rodgers (2004). Soak Time
Distributions for 400,000 Atlanta Vehicle Trips. Conference Presentation for March 2004,
14th CRC On-Road Vehicle Emissions Workshop.
Morton, Jonathan (2005). The 13-County Atlanta Metropolitan Area Mobile Source
Emissions Inventory Data. Personal communication (November, 2005).
Ogle, J., Guensler, R., and V Elango (2005). "Commute Atlanta Value Pricing Program:
Recruitment Methods and Travel Diary Response Rates"; Transportation Research Re-
cord; No. 1931; pp. 28-37. National Academy of Sciences; Washington, DC.
U.S. EPA (2001). Soak Length Activity Factors for Start Emissions. Publication No.
EPA420-R-01-011. U.S. Environmental Protection Agency.
U.S. EPA (2003). User's Guide to MOBILE6.1 and MOBIILE6.2 Mobile Source Emis-
sion Factor Model. Publication No. EPA420-R-0.-010. U.S. Environmental Protection
Agency.
53
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