EPA-450/3-75-072
    August 1975
                          APPLICATION
              OF  THE HIWAY MODEL
                        FOR INDIRECT
                   SOURCE ANALYSIS -
                       USER'S MANUAL
~
            U.S. ENVIRONMENTAL PROTECTION AGENCY
               Office of Air and Waste Management
            Office of Air Quality Planning and Standards
            Research Triangle Park, North Carolina 27711

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                          EPA-450/3-75-072
       APPLICATION
OF  THE HIWAY MODEL
     FOR INDIRECT
  SOURCE ANALYSIS -
  USER'S  MANUAL
              by

         Kenneth Axetell, Jr.
         808 S. Fairfax Street
       Alexandria, Virginia 22314

     Purchase Order No. 5-02-3670A
 EPA Project Officer:  Edwin L. Meyer, Jr.
           Prepared for

 U. S. ENVIRONMENTAL PROTECTION AGENCY
    Office of Air and Waste Management
 Office of Air Quality Planning and Standards
    Research Triangle Park, N. C. 27711

            August  1975

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This report is  issued  by the Environmental Protection Agency to report
technical data of interest to  a limited number of readers.   Copies are
available free of charge to Federal  employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the
Air Pollution Technical Information  Center,  Environmental Protection
Agency,  Research Triangle Park, North Carolina 27711; or, for a
fee,  from the National Technical Information  Service,  5285  Port Royal
Road,  Springfield, Virginia  22161.
This report was furnished to the Environmental Protection Agency by
Kenneth Axetell,  Jr., Alexandria, Virginia  22314, in fulfillment of
Purchase Order No.  5-02-3670A.  The contents  of this report  are repro-
duced  herein as received from  Kenneth Axetell, Jr.   The opinions,
findings, and conclusions  expressed are those of  the  author and not
necessarily those of the Environmental Protection  Agency.  Mention
of company or  product names is not to be  considered as  an  endorsement
by the Environmental  Protection Agency.
                   Publication No.  EPA-450/3-75-072
                                   11

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   APPLICATION OF THE HIWAY MODEL
    FOR INDIRECT SOURCE ANALYSIS
            USER'S MANUAL
           PREPARED FOR THE
U.S. ENVIRONMENTAL PROTECTION AGENCY
     UNDER ORDER NO. 5-02-3670A
                  BY
         KENNETH AXETELL, JR.
             JULY 23, 1975

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                                 TABLE OF CONTENTS



1.   INTRODUCTION                                                       1

2.   PROCEDURE FOR ANALYSIS USING HIWAY MODEL                           3

3.   SIMULATION OF PARKING LOT EMISSIONS AS LINE SOURCES                5

     RATIONALE FOR SIMULATION AS LINE SOURCES                           5

     METHODOLOGY FOR ALLOCATING PARKING LOT EMISSIONS                   7

4.   COMPILATION OF EMISSION DATA                                      18
     SOURCE CONFIGURATION                                              18

     RECEPTOR LOCATION                                                 27
     METEOROLOGICAL DATA                                               29
          Wind Direction                                               29
          Wind Speed                                                   31
          Mixing Height                                                32
          Stability Class                                              33
     EMISSION DATA                                                     36

          Emission Rates for Parking Area Traffic Lanes                36
          Emission Rates for Access Streets                            37
          Emission Rates for Queues                                    40
     SELECTION OF ALTERNATIVES FOR MODELING                            41

5,   INPUT DATA FORMAT FOR THE HIWAY MODEL                             44

6.   OUTPUT DATA AND ITS PRESENTATION                                  49

7.   ESTIMATION OF-MAXIMUM 8-HOUR CO CONCENTRATIONS                    54

     REFERENCES                                                        57

     APPENDIX                                                          58

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                                    LIST OF FIGURES

 Figure                                                                  Page

   1.   Flow diagram for indirect source analysis using                    4
        HIWAY model

   2.   Example distribution of vehicles from one entrance                 9
        to parking spacing

   3.   Convention/exhibition hall                                        13

   4.   Distribution of vehicles from entrance B to                       15
        parking spaces

   5.   Example base map with coordinate system superimposed              20

   6.   Simulation of curving streets with straight line                  22
        segments

   7.   Location of receptor relative to line source end                  26
        points

   8.   Composite emission factors for carbon monoxide for                39
        calendar year 1975

   9.   Assembly of HIWAY card deck                                       47

  10.   Example of HIWAY output                                           50

A 41.   Proposed shopping center and surrounding area                     59
                                    LIST OF TABLES

 Table                                                                   Page

   1.   Allocation of parking lot emissions to traffic links              11

   2.   Example allocation of parking lot emissions to                    17
        traffic links

   3.   Input data requirements for HIWAY                                 19

   4.   National Weather Service upper-air observing stations             34

   5.   Estimation of Pasquill stability classes                          35

   6.   Input data format                                                 45
                                      11

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                             LIST OF TABLES (Continued)

 Table                                                                   Page

   7.   Calculation of total CO concentrations at receptor                51
        sites

 A 1.   Traffic demand by hour on peak traffic days                       60

 A 2.   Average speeds on access streets                                  61

 A 3.   Data on intersection designs                                      62

 A 4.   Wind directions during hours with wind speed of                   64
        1.0 m/sec or less

 A 5.   Number of annual occurrences of wind speed - 1 m/sec              65
        by hour of day and concurrent stability class

 A 6.   Maximum 1- and 8-hour CO concentrations at an existing            66
        suburban shopping center

 A 7.   Emission factors for access streets                               69

 A 8.   Allocation of parking lot emissions to traffic links              71

 A 9.   Emission rates by lane for access streets                         72

A 10.   Queue lengths and emission rates                                  74

A 11.   Configuration of line sources                                     75

A 12.   Receptor site locations                                           77

A 13.   Subtotals of model-predicted contributions from 32 line           79
        sources under different alternatives

A 14.   Predicted maximum 1- and 8-hour CO concentrations at              81
        proposed site
                                      111

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1.   INTRODUCTION



     This document describes a detailed methodology for employing EPA's



HIWAY model for microscale analysis of proposed indirect sources.  The



recommended methodology may be used to obtain a more accurate estimate



of maximum carbon monoxide (CO) concentrations in cases where the



screening procedure in the Guidelines for the Review of Indirect Sources



indicates that the National Ambient Air Quality Standards (NAAQS) would



possibly be exceeded, or it may be used initially in complex analyses



that are not readily handled by the screening procedure.  It is appli-



cable for all types of indirect sources, but was developed particularly



for those indirect sources with emissions from both access streets and



parking areas.



     The methodology relies on emission estimates for specific types of



indirect sources calculated by the procedures presented in Appendices A



through G of the Guidelines, and draws upon other procedures included in



the Guidelines and its appendices (e.g., selection of receptors and



estimation of background concentrations).



     Use of the HIWAY model in the analysis does require access to EPA's



UNAMAP system or installation of the HIWAY program on the user's com-



puter.  However, once the program is on line, very little knowledge of



computer operations is necessary to use the HIWAY model for indirect



source analysis.  Simple instructions on the preparation of input data



and interpretation of output are provided in this document.  The User's


               2
Guide for HIWAY  is a reference for additional information on the model.



     For indirect sources with pollutant contributions from access



streets, entrance/exit queues and parking areas, computer analysis

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greatly reduces the calculation effort for the several different alter-

natives that may need to be considered.  For example, peak traffic on

the access street may occur at a different time of day than peak traffic

movement in the parking areas, or the most adverse meteorological

conditions may never occur during periods of the day with peak traffic.

In either of these cases, more than one time period must be analyzed.

Also, with the additive effect of pollutant contributions from several

sources, different wind directions should be investigated to determine

the direction resulting in maximum concentrations at each receptor site.

     In addition to its efficient handling of multiple line sources and

of different alternatives, the HIWAY model has several analytical advan-

tages over the screening procedure:

     -  complicated source configurations can be simulated;

     -  meteorological and traffic data specifically applicable to
        the site can be input;

        use of the same dispersion equation for all sources is
        assured.

     The HIWAY model accepts only line source emissions, so a procedure

for allocating parking lot emissions to the major traffic lanes within

the parking lot has been developed.  It is explained and demonstrated in

Chapter 3.  Chapter 2 outlines the individual steps in the indirect

source analysis; Chapter 4 explains how to compile the required input

data; Chapter 5 describes formatting procedures for the HIWAY model;

Chapter 6 describes the output of the HIWAY model; and Chapter 7 dis-

cusses approaches for estimating 8-hour CO concentrations.

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2.0  PROCEDURE FOR ANALYSIS USING THE HIWAY MODEL




     The steps involved in using the HIWAY model for indirect source




analysis are shown in the flow diagram of Figure 1.  This flow diagram




may be used as a checklist while performing the analysis.




     Specific information on how to perform each step is explained in




subsequent chapters.  Page numbers are shown in Figure 1 to assist in




locating the appropriate instructions for each step.




     As shown in Figure 1, the types of input data that must be gener-




ated are source-receptor distance measurements, CO emission rates, and




meteorological data.  Most of the steps are associated with development




of these input data, but the final steps relate to handling and inter-




pretation of the HIWAY model output.

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 CONFIGURATION
 OP SOURCES
 AND RECEPTORS
EMISSION DATA
 METEOROLOGICAL
 DATA
Obtain drawings or
map to scale showing
proposed site, access
streets & receptors
Make copy for use
as base map
      p. 18
                            p.  18
                        p.  18
                  Obtain projected
                  traffic volumes in
                  parking area by hour
                  and by ent./exit
                  Obtain projected
                  traffic volumes and
                  speeds on access
                  streets by hour
                        p. 37
 Obtain representa-
 tive wind speed and
 direction data
                          Select  time  periods
                          for  analysis:
                           - 1 &  8  hour  daily
                            periods
                           - season
                           - critical  year

                          May  need  to  analyze:
                           - peak traffic at
                            source
                           - peak traffic on
                            access streets
                           - worst  met.
                            period
                           - no-build
                            condition
                                                 p. 41
                                                                     Identify major traffic
                                                                     aisles  in parking  lot
                                                                          p. 8
                          Determine  emission
                          factors  &  average
                          running  times  in lot
                                                                          p. 6
                          Determine  locations  &
                          lengths of major
                          queues
                                                                          p. 23
                                                                    Determine emission
                                                                    factors
                                                                          p. 38
                            29
Specify for each
time period:
 - wind speed
 - mixing height
 - stability clas
                                                                           pp.  31-35
Mark all line sources
on map; record grid
coords, of end points
                                                                                                                       Select  receptor  sites
                                                                                                    p. 21
                                                                                 p.  27
                                                                               Distribute emissions
                                                                               to lanes in parking
                                                                               lot
                                                                                                       p.  10
   Calculate  total
   emissions  for parking
   lot
                                                                                                       p.  6
  Calculate emission
  rates for queues
                                                           p.  40
                                                     Calculate emission
                                                     rate  for each
                                                     street  lane
                                                                                                      p. 37
                                                    Select wind directions
                                                    for max. concentration
                                                    at receptors
                                                                                                     pp. 29-30
                                                        Figure  1.   Flow diagram  for  indirect  source analysis using HIWAY model
                                                                           Determine grid coords.
                                                                           of receptors,  includ-
                                                                           ing height
Obtain or estimate
other dimensions
                                                                                                                                    pp. 23-24
                                                                                                                                                     p.  28
                                                                                                  Code input data,
                                                                                                  keypunch,  and run
                                                                                                  HIWAY program
                                                                                                                                                                pp. 43-47
                                                                       Tabulate and total
                                                                       concentrations from
                                                                       all  sources  at each
                                                                       receptor
                                                                                                                                                                   pp. 48,50
                                                                                                                         Modify concentrations
                                                                                                                         for 8-hour averages
                                                                       Determine persistence
                                                                       factor for 8 hours
                                                                                                                                                                           p. 53
                                                                                                                                                                p.  49
                                              Summarize  CO concen-
                                              trations for all
                                              conditions analyzed
                                                                                                                                                                      52
                                                                                                                                            Compare with NAAQS,
                                                                                                                                            draw conclusions
                                                                                                                                                  p. 52

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3.0  SIMULATION OF PARKING LOT EMISSIONS AS LINE SOURCES




3.1  Rationale for Simulation as Line Sources




     The detailed procedures for estimating emissions in parking lots




described in Appendices B through G of the Guidelines indicate that only




a small percentage of the total automotive running times in the lots are




associated with parking and unparking the vehicles at the parking spaces.




Most of the running time and emissions are associated with movement




along the entrance/exit lanes to the parking areas, movement on the main




traffic aisles within the parking areas, and stop-and-start travel in




queues on these aisles (each with one or more traffic lanes).  There-




fore, a procedure which assigns parking lot emissions to a series of




line sources representing these major traffic aisles generally should




more accurately simulate the distribution of emissions than an assump-




tion of uniform emission density throughout the parking lot.  This is




particularly true when a structure such as a shopping center or stadium




occupies a large portion of the area within the parking lot.




     In order to utilize the HIWAY model for parking lot analysis and to




more accurately simulate the actual distribution of emissions within




parking lots, a methodology has been developed to distribute the esti-




mated emissions among several line sources representing the major




traffic aisles.  It should be emphasized that this methodology is




strictly for distribution of emissions, and that the emissions are still




to be calculated by the procedures described in Appendices B through G




of the Guidelines.




     The steps in estimating emissions from the parking areas vary with




each specific type of indirect source, but all are based on the same

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principle—that total carbon monoxide emissions from motor vehicles,


exclusive of emissions from major queues, can be calculated by multiply-


ing the number of vehicles moving in the lot during any period by the


average running time per vehicle, times an appropriate emission factor


for CO emitted per vehicle-minute of operation:

                      , (EF) (V) (RT)

               y         216,000


               Q   =   emissions from mobile sources, gm/sec

                                                  *          .•
              EF   =   emission factor, gm/min-veh


               V   =   traffic demand, veh/hr


              RT   =   typical vehicle running time, sec
                   -=   conversion factor from 3?' °"^ to gm/sec
         216,000


The average running time is estimated as the sum of a base running time


required for driving between the access street and the parking spaces


under congestion-free conditions and an incremental running time result-


ing from traffic congestion.


     Running times in major queues  (RT ) at entrances/exits and inter-


sections within the parking lot should not be included in the estimated


running time described above.  Instead, the major queues are to be


considered as separate line sources, with emission rates calculated by


the procedure described in Section 4.4.3 of this document.  The parts of


the traffic aisles on which the queues occur are still identified as


line sources receiving an apportionment of parking lot emissions  (Q)


because there are also cruising vehicles using these parts of the aisles.


The emission rates for the additional line sources simulating queues


only account for the excess emissions  (or running times) occurrina
*See Figure 8, page 39 for appropriate emission factor values.


                                   6

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over the queue lengths as a result of acceleration/deceleration and




idling..




     In most cases the parking lots being analyzed have not yet been




built, so the process of apportioning emissions to traffic aisles within




the parking lot is just an extension of the estimating procedure used to




predict average running times in the lots.  Both processes require that




assumptions of preferred parking areas and travel paths within the




parking lot be made.  Also, detailed plans of the parking lot, including




locations of traffic lanes and entrances/exits, are necessary in both




cases.  Comparatively, more latitude may be exercised in predicting




vehicle movement within parking lots for purposes of emission distri-




bution, since any rational traffic assignment should result in an im-




provement over the assumption of vehicles being uniformly distributed




throughout the lots.




     Thus, the traffic assignments can be made from a knowledge of the




entry points and destinations of vehicles within the parking area by




subjectively determining preferred travel routes.  The methodology for




apportioning emissions is outlined in detail in Section 3.2.









3.2  Methodology for Allocating Parking Lot Emissions to Traffic Lanes




     1.  Obtain estimates of the number of vehicles entering and exiting




at each entrance/exit to the parking area during the time period of




concern.




     2.  Identify the desired ultimate destination points within the




development and the number or percent of trips bound for each identified




destination point (based on building entrances, tenant mix, ticket booth




locations, walking distances from parking area, etc.).




                                   7

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      3.  Using a drawing or map  to  scale of the development and  its




parking area, mark  the major movement routes of vehicles to parking




spaces nearest the  destination points.  Some of the traffic aisles may




be used on  routes from more than one entrance.  Do not  show the  indi-




vidual parking aisles unless traffic other than that parking along the




aisle would normally use it in traveling through the parking lot.




      4.  Mark nodes on the drawing  at points where the  traffic movement




splits or where there should be  a significant change in traffic  volume




as some of  the cars park.  Number the resulting traffic links between




each  pair of nodes.




      5.  Starting at one entrance,  estimate the distribution of  vehicles




at each node  (intersection) by assigning percentages of the traffic




reaching the node to each link  (aisle)  leading away from that node.  The




traffic volume leaving the node  will not equal 100 percent if some




vehicles park in the vicinity of that node.  Continue splitting  the




traffic coming from the entrance onto subsequent links  until it  is all




distributed to parking areas.  Repeat this procedure for the other




entrances.   (There  is no need to consider links carrying less than two




percent of  the total traffic in  the parking lot, as this would increase




the number  of line  sources in the HIWAY model without greatly increasing




the accuracy of emission distribution.)  This step is shown schemati-




cally in Figure 2.




      6.  If aisles  are two-way and  motorists would normally use  the  same




aisles to exit as they did to enter, no separate distribution for




exiting vehicles need be performed. However, if the aisles are  designed




for one-way traffic or if entrances and exits are located at different




points on the periphery of the parking  lot, the procedure described




                                    8

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( !
n
2850 veh/hr in (60% of total) c
240 veh/hr out (60% of total) 1 -^
entrance A |
link 1 I
50% 1

30% ^_,
parking 1
'
70%
60%
par
40%l


•king 40%
4 parking
40%
-H
r-\
30%
link 7 y
70%
50% 5,°%
parking
H
rH

I •
•H
i-H

C
•H
•

door 1
30%

door 2
'', 30%

\
[ door 3
/ 40%


parking
Figure 2.  Example distribution of vehicles from one entrance to
parking spaces

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in step 5 should also be conducted for traffic exiting during the corre-

sponding time period.  The starting points with exiting traffic are the

parking lot exits; otherwise, the procedure is completely analogous to

that described above.

     7.  Measure the length of each link carrying two or more percent of

the traffic and record these values in the tabular format shown in Table

1-

     8.  Determine a weighting factor for each link by multiplying its

length by the fraction of total traffic traveling in the aisle.  Total

the weighting factors, then determine the constant (c) for calculating

line source emission rates for the HIWAY model by dividing the estimated

parking lot emissions by the total of the weighting factors:

               c   =   —:—*—  , where
                      ^-1 i i

               Q   =   parking lot emissions, gm/sec

               P.  =   fraction of running vehicles using traffic
                       link i

               L.  =   length of link i, any consistent units

If separate analyses are performed for entering and exiting traffic,

then subtotals for emissions due to entering vehicles  (Q. ) and exiting

vehicles (Q   ) must be used to calculate separate weighting factors for

the two analyses.

     9.  Calculate the line source strength of each link  (in gm/sec-m):

               q.  =   cP./z  , where

               z   =   factor to convert units of length to meters

These calculations should be recorded in the same table as used in steps

7 and 8.


                                   10

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            Table 1.  ALLOCATION OF PARKING LOT EMISSIONS TO TRAFFIC LINKS
Traffic
 link
Length
Fraction of entering or exiting
   vehicles using this link
Weighting
 factor
Line source strength,
      gm/sec-m
                                         11

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     10.  Divide the total line source strength for each link into




emission rates per lane.  The relative emission rates for traffic in




each direction on two-way aisles are estimated to be the same as the




ratio of entering to exiting vehicles at the entrance/exit serving




this traffic aisle.  If separate distributions are performed for entering




and exiting traffic (see step 6 above), the traffic volumes in each




direction on the aisle can be calculated.  Unless specific information




to the contrary is available, the emissions from travel in each direc-




tion should be divided uniformly among the lanes in that direction.




     11.  Indicate the locations of major queues in the parking area




that were segregated to be input as separate line sources.  The line




source strength and upstream length of each queue should be calculated




per the instructions in Section 4.4.3 and 4.1, respectively.




EXAMPLE




     Problem.  The convention/exposition hall design shown in Figure 3




has two parking lot entrances/exits.  During the peak hour, traffic




through the main entrance is estimated to be 2,850 in and 240 out.




Traffic through the other gate would be 1,900 in and 160 out.  All




internal traffic aisles have two lanes and are designed for two-way




traffic.




     The developer estimates that approximately 60 percent of the




persons entering the hall will enter through doors 1 and 2  (30 percent




each) while 40 percent will enter through door 3.  Average vehicle




running times (in O£ put) during the peak hour are estimated to be 175




seconds, and parking lot emissions  (Q) are calculated to be 79.3 gm/sec.




Distribute the emissions to line sources within the parking lot and




estimate line source strengths for input to HIWAY.





                                  12

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                                  residential area
commercial
      main
      ent.
apartments
commercial
                                    x \  •  \  \,

                                    ''t&rrace ^'v x ,
   Figure 3.  Convention/exposition hall
                                  13

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     Solution.
     a.  Traffic volumes and destination points are given.  From this
information and the map showing locations of traffic lanes and parking
spaces, major movement routes can be identified and traffic links can
be identified and marked.  This is shown separately for each of the
entrances in Figures 2 and 4.
     b.  The distribution of vehicles at each intersection is determined
subjectively.  The vehicles from Entrance A (Figure 2) account for 60
percent of the total and are nearest doors 1 and 2, which likewise
account for about 60 percent of the attraction points.  Since there is
adequate parking approximately equidistant from the two doors, the
traffic would probably split in half at the first intersection.  Traffic
on link 2 would park as near to door 1 as possible, with those vehicles
unable to find a parking space (50 percent) continuing on to link 3.  A
similar process would occur with vehicles on links 4 and 5, except that
some might continue on this traffic lane attempting to find a parking
space near door 3.  However, they would be competing for these spaces
with vehicles from Entrance B.
     In summary, the estimates of traffic splits and vehicles parking
are based on available parking spaces and proximity to the convention
hall entrances.  The values for vehicle distribution presented in this
example are for illustrative purposes and should not be applied directly
in other analyses.
     c.  Distribution of vehicles from Entrance B (Figure 4) is based
primarily on attraction to door 3, although some vehicles  (16 percent in
this example) would undoubtedly continue along the main traffic lane to
park nearer to door 2."
                                   14

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                                                       door 1
20%
                         20%
                     •4
               link 8
                      40%"
                    parking
            Oi
                    40%-* - L
           V
          link 7
     80%        20%
   parking    parking

                 40%

             10% •**"""
           parking
                             vD
                                    /
                                                        30%
                            I'door 2
                             \r 30%
                             P/
                                     door 3
                                      40%
                                             j//s ////// j/j/se/ xx
                              50%
                              entrance B
                                       link 12
                                 1900 veh/hr in  (40% of total)
                                  160 veh/hr out (40% of total)
Figure 4.   Distribution of vehicles  from entrance B to parking spaces
                               15

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     d.  The length of each link is scaled from the map and recorded in




Table 2.




     e.  The fraction of total incoming vehicles using each link is then




calculated as shown in Table 2, and a weighting factor determined for




each link.




     f.  The constant for calculating line source strengths is deter-




mined to be .0643 by dividing parking lot emissions (79.3) by the sum of




the weighting factors (1,234).




     g.  The line source strengths for each link are then calculated




using the equation q. = cP./z.  The conversion factor  (z) from feet to




meters is 0.305.  Resulting values are recorded in Table 2.




     h.  The ratio of entering to exiting vehicles is the same at both




entrances/exits, 11.83 to 1.  The emission rates for each lane are




calculated from this ratio, with the emission estimates for links 5, 6




and 9 also requiring data on the percentage of traffic from each en-




trance.  The emission data for input to HIWAY are summarized in Table 2.
                                   16

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Table 2.  EXAMPLE ALLOCATION OF PARKING LOT EMISSIONS TO TRAFFIC LINKS
Traffic
link
1
2
3
• 4
5
6
7
8
9
10
11
12

Length
feet
500
720
350
400
400
450
380
380
450
350
280
650

Fraction of entering or exiting
vehicles using this link (p)
(.6) = .60
(.6) (.5) = .30
(.6) (.5) (.5) = .15
(.6) (.5) = .30
(.6) (.5) (.7) +
(.4) (.4) (.4) (.2) = .22
(.6) (.5) (.7) (.4) +
(.4) (.4) (.4) = .15
(.6) (.5) (.7) (.4) (.3) +
(.4) (.4) (.4) = .09
(.6) (.5) (.7) (.2) +
(.4) (.4) (.4) (.4) = .07
(.6) (.5) (.7) (.2) (.4) +
(.4) (.4) (.4) (.2) = .03
(.4) = .40
(.4) (.4) = .16
(.4) (.5) = .20

Weighting
factor
300
216
52
120
88
68
34
27
14
140
45
130
1,234
Line source
strength, g/ra-s
0.1264
0.0632
0.0315
0. 0632
0.0464
0.0315
0.0190
0.0147
0.0063
0.0843
0.0337
0.0421

Emission rate
S or E lane
0.1166
0.0583
0.0291
0.0049
0.0059
0.0139
0.0015
0.0011
0.0028
0.0778
0.0311
0.0388

by lane, gm/sec-m
N or W lane
0.0098
0.0049.
0.0024
0.0583
0.0405 s
0.0176
0.0175
0.0136
0.0035
0.0065
0.0026
0.0033


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4.0  COMPILATION OF INPUT DATA




     The data that must be compiled in order to run the HIWAY model are




shown in Table 3.  These data may be classified into four general cate-




gories:  source configuration (measurements of the site and surrounding




area), receptor location, meteorological data, and emission data.  The




steps to be followed in obtaining or generating all of these data are




explained in this chapter.  The final section of this chapter describes




the selection of specific combinations of emission data and meteoro-




logical data for input to the model to simulate CO concentrations during




different time periods.




4.1  Source Configuration




     The distance between sources and receptors must be accurately




defined in the analysis.  This is normally accomplished by obtaining an




engineering drawing or site plan of the proposed development plus a




large enough surrounding area to include all potential receptor sites.




A copy of the drawing or plan should be made so that notations and




additional markings can be written on it.  A base map should then be




prepared from this copy by placing a coordinate system on the map and




marking each access street and parking lot traffic link as a straight




line (along the centerline of the street or lane) with well-defined end




points.




     Any convenient units can be used for the coordinate system; prob-




ably those of the base map would be easiest to apply.  If the arbitrary




origin of the coordinate system is placed to the south and west of all




line source end points and receptor locations, the (x,y) coordinates
                                    18

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              Table 3.  INPUT DATA REQUIREMENTS FOR HIWAY
Source Configuration
        Coordinates (x,y) of line source end points
        Source height
        Total width of highway
        Width of center strip
        Number of traffic lanes
        Cut section or at-grade highway
        Width of cut section
        Factor to convert site measurements to kilometers
Receptor Location

        Coordinates (x,y) of receptor
        Receptor height
Meteorological Data

     -  Wind direction
     -  Wind speed
        Mixing height
        Stability class
Emission Data

        Line source emission rate for each traffic lane
                                   19

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                                                                           2500
Figure 5.  Example base map with coordinate system superimposed
                                 20

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will all be positive.  However, the model will accept negative coordi-




nates.  An example base map with a coordinate grid superimposed is shown




in Figure 5.




     The locations of the line sources are input to the HIWAY model by




the grid coordinates of the two end points of each link.  Distances




between line sources and receptors are calculated in the model from




their respective coordinates.  Because of the importance of the source-




receptor configuration to the accuracy of the analysis, it is recom-




mended that coordinates used in the model be checked by calculating




distances between key points trigonometrically and comparing these




values with measurements between the corresponding points scaled directly




from the base map.  For crucial dimensions, such as the distance of a




public sidewalk from the edge of an access street or parking lot entrance,




field measurements of these small distances (if facilities are already




in existence, this is preferable to scaling from the base map) should be




used in conjunction with coordinates for the line source to calculate




the exact grid coordinates of the receptor.  (Receptor location is also




discussed in Section 4.4.)  Calculation of receptor coordinates relative




to line source end points is demonstrated in the example at the end of




this section.




     Non-linear streets or lanes must be represented in the HIWAY model




by straight-line segments.  Generally, this may be done more accurately




by keeping the line on the base map over some part of the street rather




than by connecting points on the centerline of the curving street.  The




correct procedure is shown in Figure 6.  Attention to this procedure is




important only when receptors are to be specified in the model near the




non-linear street's edge.




                                  21

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Incorrect
Correct
      Incorrect
                                           Correct
Figure 6.  Simulation of Curving Streets with Straight Line Segments
                                 22

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     If emission rates change substantially along a street due to


different traffic volumes or speeds, the street should be split into


separate line sources at the points where the emission rates change.


For an access street on which emission rates remain fairly constant over


the length of the street, end points of the line source should be


extended sufficiently so that any portion of the length that would


impact on a downwind receptor (with a wind direction specified in the


analysis) is included.


     No distinction is made in the model among any of the three types of


line sources that are included—access streets, major traffic aisles in


parking areas, and major queues on either the access streets or the


parking areas.


     The sources representing queues have a finite length.  This length


is calculated from equations presented in the Guidelines:


At signalized intersections


                       V(l-G/Cy)D

                          CPH


         where L   =   queue length, meters


               V   =   traffic demand, veh/hr


            G/Cy   =   green time to signal cycle ration, dimensionless


               D   =   spacing between successive vehicle tailpipes in

                       the queue, assumed to be 8 m/veh


             CPH   ='   number of signal cycles per hour


 At rioh-signalized intersections

                      r   v2  ,
               L
         where C   =   capacity, veh/hr, and other symbols are as

                       defined above
                                  23

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One end point for the queue is the intersection.  The other end point




can be calculated after the length of the queue is determined.  If the




queue length is less than 25 meters (about three vehicles), it should




not be included in the model as a separate line source.




     Several other dimensions and data values must be provided to fully




define the source configuration.  The additional dimensions are:  (1)




height of the line source above ground level, (2) total width of the




street, (3) width of the median strip (if present), and (4) width of cut




section at its top (if the street is in a cut section).  All of these




dimensions must be input in units of meters rather than the units used




for the coordinate system.  Three other pieces of information must be




specified:  (1) the number of lanes in the street, (2) whether the




street is in a cut section, and (3) the scale factor for converting the




coordinate system units to kilometers.  Scale factors for the most




common units are shown below:




               Map units                Scale factor




               feet                     0.0003048




               miles                    1.6093




               meter                    0.001




               kilometers               1.




     The HIWAY model is only applicable to relatively flat terrain.  For




at-grade streets, the height of the line source may be estimated as 0.0




rather than tailpipe height  (0.5 meter)  without any loss of accuracy




because an initial vertical dispersion of 1.5 meters is included in the




model.




     The width of the street or highway should include the width of any




center median present, but not the highway shoulders.  If the width is




not specified in the material submitted and cannot be accurately measured




                                  24

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from the drawing, an estimate of 12 feet  (3.66 meters) per lane may be

made for modern main streets and highways.   If the right-of-way width

is obviously limited by existing development, an estimate of 10 feet

(3.05 meters) per lane may be more appropriate.

EXAMPLE

     Problem.  A receptor site located on the centerline of a sidewalk

is 6 feet from the edge of the curb of a major access street to a shop-

ping center, as shown in Figure 7.  The street, including curbs, is 52

feet wide.  The coordinates  (in feet) specified for its end points are

(165, 300) and (366, 416).   If the receptor  is 80 feet  (measured along

the street) from the intersection denoted by the coordinates  (165, 300),

what are the coordinates of  the receptor  site?

     Solution.

     a.  Distance (d) of the receptor from the centerline of the street

is:
                         d   =   52_  +  6
                                  2
                                 32 feet

     b.  The angle  (a) formed by the street  and the x-axis is calculated

as follows:
                                        416  - 300
                         a   =   arctan 366  - 165

                                 arctan 0.557
                             =   30.0°

     c.  The coordinates of  the receptor  can then be  calculated trigo-

nometrically:

                         x    =   165 + 80 cos a + 32 sin a
                          i\
                                  250
                         y    =   300 + 80 sin a - 32 cos a
                          R
                                  312
                                    25

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                                                           416
      165
Figure 7.  Location of receptor relative to line source end points
                                26

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4.2  Receptor Location




     Critical receptor sites are usually the nearest "reasonable" loca-




tions to streets tor traffic lanes with the highest line source strength




and locations immediately downwind of a group of line sources.  For an




indirect source with emissions from both access streets and a parking




area, these locations are usually near an intersection of access streets




or near an entrance/exit to the parking area.  By using the HIWAY model,




all potential points of maximum CO concentration can be evaluated simul-




taneously.  Up to 50 receptor sites can be specified in the HIWAY run.




     The Guidelines recommend that receptor site selection be through




joint review of maps and plans of the area by the reviewing agency and




the applicant.  Several examples of locations that would generally be




regarded as reasonable and unreasonable receptor sites are presented in




the Guidelines and are repeated herein:




Examples of Reasonable Receptor Sites




     1.  All sidewalks where the general public has access on a more or




less continuous basis for 1- or 8-hour periods.




     2.  A vacant lot in which a neighboring facility is planned and in




whose vicinity the general public (including employees if the neigh-




boring facility is not being built for the prime purpose of traffic




control) would have access continuously for 1- and 8-hour periods.




     3.  Portions of a parking lot to which pedestrians have access




continuously for 1- and 8-hour periods.




     4.  The vicinity of a parking lot's entrances and exits, providing




there is an area nearby, such as a public sidewalk, residences, or




structures (e.g., an auto service center at a shopping center), where
                                  27

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the general public is likely to have continuous access for 1 or 8 hours.




     5.  The property lines of all residences, hospitals, rest homes,




schools, playgrounds, and the entrances and air intakes to all other




buildings.




Examples of Unreasonable Receptor Sites




     1.  Median strips on roadways.




     2.  Locations within the right-of-way on limited access highways.




     3.  Within intersections or on crosswalks at intersections.




     4.  Tunnel approaches.




     5.  Within tollbooths.




     6.  Portions of parking lots where the general public is not




likely to have access for 1- or 8-hour periods.




     Some other receptor sites may be of special interest, even though




they are not anticipated to be points of maximum CO concentration in the




area, because sensitive members of the population are likely to be




exposed there.  These special receptors might include schools, play-




grounds, day care centers, hospitals, sanitariums, nursing homes, and




parks.




     The x and y coordinates of all receptor sites must be specified in




the same units as the line source end points.  It is important that the




receptors' grid coordinates be determined from the same base map used to




fix the location of the line sources so that possible errors in defining




the source-receptor relationship are minimized.




     The heights of all receptor sites must be specified in meters.




Normally, receptor height would be about two meters above ground level,




at nose height.






                                  28

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4.3  Meteorological Data




     Meteorological input data for the analysis should be specified to:




(1) result in the maximum Co concentrations that may occur at receptor




sites and (2) be consistent with observed meteorological conditions that




are representative of the site for the time periods of concern.  Four




different meteorological inputs are required for the HIWAY model:




               -  wind direction




                  wind speed




               -  mixing height




                  stability class




     To provide assurance that the specified data are consistent with




actual meteorological conditions, a full year's records from a nearby




meteorological station should be obtained and reviewed.  Joint frequency




distribution for wind direction, wind speed, and stability class (e.g.,




the STAR program output available from the National Climatic Center)




will indicate whether certain critical combinations of these three




variables occur with sufficient frequency to be considered in the anal-




ysis.  However, these frequency distributions are not normally generated




for a specific hour of the day, so the raw data still must be scanned to




determine whether the critical combinations of wind direction, wind




speed, and stability class ever occur during the hour(s) with highest




emission rates.  If not, it is also important to determine the hours in




which these adverse meteorological conditions do occur.




     4.3.1  Wind Direction




     The wind directions to be investigated should be selected based on




the locations of receptors relative to sources, with the receptors







                                   29

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falling downwind of major line sources.  Obviously, this may require the




analysis of several wind directions if receptors have been specified in




different directions from the proposed development site.  Since there is




no simple procedure for isolating the wind direction or receptor site




that will result in the highest CO concentrations, each wind direction




must be modeled separately.  A major advantage of the HIWAY model com-




pared to the screening procedure is its ability to analyze several




receptors and alternative sets of meteorological input data efficiently.




     The base map showing locations of sources and receptors provides an




excellent aid in establishing the wind directions for use in the model.




     Several general guidelines are applicable to the selection of wind




directions for the model:




     1.  For receptors near a large number of short line source segments,




as in a parking lot or adjacent to intersection approaches, a wind




direction that places the maximum number of these sources directly




upwind should be used.




     2.  For receptors near (within about 10 meters) access street line




sources which extend for a long distance (more than 100 meters) beyond




the receptor location, a wind direction parallel or nearly parallel to




the line source should be considered in estimating maximum 1-hour con-




centrations.  Parallel winds are not appropriate for estimating 8-hour




concentrations because winds would not persist parallel to the street




for such an extended period.




     3.  For receptors more distant from sources, the wind direction




should place the receptor directly upwind of the nearest access street




intersection or parking lot entrance/exit.







                                   30

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     4.  The wind direction most frequently associated with D or E




stability classes and low wind speeds should be considered.




     4.3.2  Wind Speed




     This is the most sensitive input in the estimation of CO concen-




trations because the diffusion equation in the model calculates ambient




concentrations as being inversely proportional to wind speeds.  For




example, a change in wind speed from 2.0 to 1.0 m/sec in the model




doubles the predicted CO concentration.




     With this inverse relationship, predicted concentrations approach




infinity as the average wind speed approaches zero.  Therefore, the




model is not appropriate for wind speeds less than 0.5 m/sec and usually




overpredicts for wind speeds less than 1.0 m/sec.  A 1.0 m/sec minimum




should be observed in indirect source analyses.




     The number of annual occurrences of a 1.0 m/sec wind speed in




conjunction with a D or E stability class and the selected wind di-




rection during the time period of concern should be determined from raw




meteorological data, if available, or National Weather Service monthly




climatological summaries before the 1.0 value is used in the model.  If




this combination of adverse meteorological conditions has not occurred




during the year, the minimum wind speed recorded for the time period




with the assumed stability class and wind direction should be input




instead.  Alternately, a different wind direction or stability class for




which a 1.0 m/sec wind speed has been recorded may be considered.




     The wind speed data should be representative of the winds at the




height of the plume from the line source.  For at-grade highways and




nearby receptors, the most appropriate height is two meters above





                                  31

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ground level.   Surface wind measurements taken at the more common height



of 10 meters may be used directly, but measurements from greater heights



should be adjusted to corresponding speeds at 10 meters height.  Wind



profiles (variations in wind speed with height) which can be used to



estimate the ratio of the wind speeds at the two heights are shown in



the Workbook of Atmospheric Dispersion Estimates,  Figures 1-1 and 1-2.



     4.3.3  Mixing Height



     In contrast to wind speed, mixing height is not a critical input



for indirect source analysis.  The distances between sources and recep-



tors, generally less than 100 meters, are so small that the ceiling on



vertical dispersion imposed by the mixing height has no effect on pre-



dicted concentrations at the receptors.



     Sufficiently accurate values for use in the model can be obtained



from the EPA publication Mixing Heights, Wind Speeds, and Potential for


                                                            4
Urban Air Pollution throughout the Contiguous United States,  Figures 1



through 10.  This compilation of mixing height data provides a selection



of values specific for the time of day, season, and national location



being analyzed.  Mean annual early morning (mimimum for the day) mixing



heights shown in this publication are 300 to 700 meters for most parts



of the country.  Afternoon (maximum for the day) mixing heights range



from 1,000 to 2,600 meters.



     Morning and afternoon mixing height values for specific dates



(e.g., to compare model results with CO sampling data) can be readily



calculated from vertical temperature profiles and surface temperature



readings available from the National Climatic Center, Asheville,



North Carolina, for any of the 62 national locations at which upper-air
                                  32

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measurements are routinely made.  The 62 cities are listed in Table 4



and the method for calculating mixing height from the vertical temper-


                                                          4
ature profile is explained in the publication cited above.   This more



detailed estimation of mixing height is not warranted for predicting



future CO concentrations in the indirect source analysis.



     4.3.4  Stability Class



     Pasquill stability classes A (very unstable) through F  (moderately



stable) are used in the HIWAY model to indicate the rate of atmospheric



mixing.  For the source-receptor configurations in indirect source



analysis, higher CO concentrations are generally predicted with increas-



ing atmospheric stability.  In order to determine the most stable poten-



tial stability class for a particular analysis, the time of day and



urban/rural location of the development site must be known.



    . In a relatively flat and open area, stability is primarily a func-



tion of wind speed and incoming solar radiation  (during the day) or



cloud cover (during the night).  The relationship is shown in Table 5.



Note that neither E nor F stability normally occurs during the daytime.



Therefore, D stability should be used to estimate the highest CO con-



centrations for all daytime hours.



     Day is defined as the period from one hour after sunrise until one



hour before sunset.   National Weather Service stations record the local



times of sunrise and sunset each day, or the official times for any date



and U.S. city can be obtained from the Naval Observatory, Washington,



D.C.



     Guidelines for estimating stability classes for open land or rural



areas are presented in Table 5.  In urban areas, the atmosphere is



likely to be less stable as a result of the mechanical turbulence



                                   33

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    Table 4.  NATIONAL WEATHER SERVICE UPPER-AIR OBSERVING STATIONS
Location
NWS
Abbr.
Location
NWS
Abbr.
Albany, New York              ALB
Albuquerque, New Mexico       ABQ
Amarillo, Texas               AMA
Athens, Georgia               AHN
Bismarck, North Dakota        BIS
Boise, Idaho                  BOI
Brownsville, Texas            BRO
Buffalo, New York             BUF
Burwood, Louisiana            BRJ
Cape Hatteras, N. C.          HAT
Caribou, Maine                CAR
Charleston, S. C.             CHS
Columbia, Missouri            CBI
Dayton, Ohio                  DAY
Denver, Colorado              DEN
Dodge City, Kansas            DDC
El Paso, Texas                ELP
Ely, Nevada                   ELY
Flint, Michigan               FNT
Glasgow, Montana              GGW
Grand Junction, Colo.         GJT
Great Falls, Montana          GTF
Green Bay, Wisconsin          GRB
Greensboro, N. C.             GSO
Huntington, W. Va.            HTS
International Falls, Minn.    INL
Jackson, Mississippi          JAN
Jacksonville, Florida         JAX
Lake Charles, Louisiana       LCH
Lander, Wyoming               LND
Las Vegas, Nevada             LAS
          Little Rock, Arkansas         LIT
          Medford, Oregon               MFR
          Miami, Florida                MIA
          Midland, Texas                MAF
          Montgomery, Alabama           MGM
          Nantucket, Massachusetts      ACK
          Nashville, Tennessee          BNA
          New York, New York            JFK
          North Platte, Nebraska        LBF
          Oakland, California           OAK
          Oklahoma City, Okl.           OKC
          Peoria, Illinois              PIA
          Pittsburgh, Penn.             PIT
          Portland, Maine               PWM
          Rapid City, S. D.             RAP
          St. Cloud, Minnesota          STC
          Salem, Oregon                 SLE
          Salt Lake City, Utah          SLC
          San Antonio, Texas            SAT
          San Diego, California         SAN
          Santa Monica, Calif.          SMO
          Sault Ste. Marie, Mich.       SSM
          Seattle, Washington           SEA
          Shreveport, Louisiana         SHV
          Spokane, Washington           GEG
          Tampa, Florida                TPA
          Topeka, Kansas                TOP
          Tucson, Arizona               TUS
          Washington, D. C.             DIA
          Winnemucca, Nevada            WMC
          Winslow, Arizona             • INW
Source:   Mixing Heights, Wind Speeds,  and Potential for Urban Air Pollution
         throughout the United States.  U.S. Environmental Protection
         Agency.  Research Triangle Park, North Carolina.  1972.  Table A-l.
                                34

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            Table 5.  ESTIMATION OF PASQUILL STABILITY CLASSES

Surface wind
speed (at 10 m) ,
m/sec

< 2
2-3
3-5
5-6
> 6
Day
Incoming

solar

Strong Moderate

A
A-B
B
C
C

A-B
B
B-C
C-D
D
radiation

Slight

B
C
C
D
D
Night
Thinly
overcast
or >4/8
low cloud

E
D
D
D

<3/8
cloud


F
E
D
D
The neutral class, D, should be assumed for overcast conditions
during day or night.
Source:  Workbook of Atmospheric Dispersion Estimates.  U.S. Depart-
         ment of Health, Education, and Welfare, Public Health Service.
         Cincinnati, Ohio.  1970.  Table 3-1.
                                 35

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created by vehicles, aerodynamic effects of buildings, and heat island




effects in highly paved areas.  This increased atmospheric mixing would




preclude E and F stability classes from occurring, except in special




situations, in urban areas.  Therefore, D stability should be used to




estimate the highest CO concentrations for urban locations, even for




nighttime periods.  For open suburban sites, E stability may be used to




stimulate night stability.




4.4  Emission Data




     The only emission data required by the HIWAY model are the line




source emission rates (q) in gm/sec-m for each lane of traffic in the




study area. Point or area source CO emissions cannot be input.  There is




no upper limit to the number of line sources that can be considered in a




single run.  One lane or any even number of lanes from 2 to 24 can be




specified for each line source.  The emission rates for multiple-lane




sources should be listed in order from left to right as the line source




is viewed from end point 1 to end point 2.




     4.4.1  Emission Rates for Parking Area Traffic Lanes




     The emission rates for traffic lanes in parking lots are calculated




by first estimating the total emissions per hour in the parking area and




then apportioning this total to the individual traffic lanes by the pro-




cedure described in Chapter 3.  This procedure produces emission rates




in gm/sec-m for direct input to the HIWAY model.




     The emissions attributable to major queues at entrances/exits and




intersections within the parking lot are not included in the emission




rates calculated for these traffic lanes.  The queue emissions, like




those from queues occurring along access streets, are considered as







                                 36

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separate line sources.  Calculation of emission rates from queues is


explained in Section 4.4.3 below.


     4.4.2.  Emission Rates for Access Streets


     Emission rates for access streets are calculated by a procedure


described in detail in Appendix A of the Guidelines, "Methods for


Estimating Emissions from Highways."  The equation used in that pro-


cedure is presented here, but it is recommended that the detailed


description be followed in the calculations.


     This equation estimates the uniform emission intensity for each


lane of freely flowing traffic on the street or highway.  The excess


emissions that occur as a result of queues at intersections are esti-


mated by additional calculations described in the next section and are


handled as separate line sources.  It should be noted that the emission


rate calculated for the free flowing segments of the access street also


extends over the length of the queue; the additional line source repre-


senting the queue only simulates the extra emissions due to acceler-


ation/deceleration and idling.


     The equation for estimating emission rates by lane is:


          q. .   =   (1.036 x 10~5) (EF) . . (V../S..)
           13                           ID   13  13

    where q..   =   line source emission rate in lane j for road segment

                    i, resulting from free flowing traffic, gm/sec-m


          V. .   =   traffic volume demand, veh/hr


          S. .   =   average vehicle operating speed, mph


        (EF)..   =   speed corrected emission factor, gm/min-veh


(1.036 x 10  )  =   conversion factor from gm/min-mi to gm/sec-m


     Volume demands for some time period(s) on all access streets


should be provided by the applicant.  If average daily traffic  (ADT)


                                  37

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volume is provided, the volume demand for the 1-hour periods of concern



can be estimated as a fraction of ADT by using data on local diurnal



traffic patterns.  Traffic volumes during particular seasons may be



estimated by applying seasonal adjustment factors.  Traffic volumes are



usually given separately for travel in each direction on a street, but



not by lane.  Therefore, the total one-way volume must be apportioned to



the lanes in that direction.



     The average operating speed on a highway link is a function of the



volume-to-capacity ratio of the link and its design speed.  Estimated



speeds during specific hours may also be provided by the applicant.  If



not, operating speeds may be estimated from Figures A2 through A5 in



Appendix A of the Guidelines.



     The CO emission factors, a function of operating speed, are pre-



sented for the year 1975 in Figure 8.  These values in units of gm/min-



veh were derived from data in EPA publication AP-42, Supplement Number



5.   For years other than 1975, the appropriate emission factor may be



estimated as follows:



             (EF) .   =  (EF)__ (ef/55)
                 yr         75


       where (EF)    =  emission factor for year of concern
                 yr


             (EF)    =  emission factor obtained from Figure 8



              ef     =  emission factor in gin/mi for the year of concern:



                             Calendar year    ef for CO
1972
1973
1974
1975
1976
1977
1978
1979
1980
70.6
65.6
61.6
55.0
48.2
41.5
35.0
29.1
23.2
                                  38

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              10    15
20    25    30    35    40    45



           VEHICLE SPEED, mph
50
55    60
65
Figure 8.  Composite emission factors for carbon monoxide for calendar year 1975

-------
     Several assumptions were made in the derivation of data in Figure 8:

          -  a national average mix of vehicles by model year

             88 percent of VMT by light-duty vehicles, 12 percent of
             VMT by light-duty trucks

             20 percent of vehicles operating from a cold start

                                               o        o
             ambient temperature in range of 68  F to 86  F

             a low altitude location outside California

If any of these assumptions are not applicable, correction factors

should be obtained from the Guidelines (Tables 1 and 2) or from AP-42,

Supplement Number 5.

     4.4.3  Emission Rates for Queues

     The emission rate for a queue on either an access street or in a

parking area is calculated from equations presented in Appendix A of the

Guidelines.  Two different types of queue formation are considered—at

signalized intersections and at non-signalized intersections.  The

average emission rate over the finite length (as determined by the

method described in Section 4.1, page 23) of a queue at signalized and

non-signalized intersections may be estimated as follows:

At Signalized Intersections
          q. .  =    (EF) .  . + 0.5  (EF) ' . .  (1 - G/Cy)

                                60 D
    where q^ _.  =  excess line source emission intensity to be applied
                  over the finite queue length L..
                  section approach i, gm/sec-m
over the finite queue length L.. in lane j at inter-
       (EF)..  =  average emission factor for accelerating and decel-
                  erating vehicles over the estimated queue length,
                  gm/min-veh

      (EF)'..  =  emission factor for idling vehicles in the queue,
           „      gm/min-veh
                                   40

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          G/Cy  =  green time to signal cycle ratio at approach i,
                   dimensionless

            D   =  spacing between successive vehicle tailpipes in the
                   queue, assumed to be 8 m/veh

The emission factors used for (EF)..  and (EF)'..  are not presented in

Appendix A, but can be derived from Supplement 5 to AP-42  and the U.S.

EPA Modal Emission Analysis Model.  Summary tables of source intensity
(q) in Appendix A of the Guidelines indicate that EF.. and (EF)'..

are a function of both signal cycle length and traffic volume.  Values

for q..  should be obtained from Tables A8 to A12 of Appendix A.

At Non-signalized Intersections

          q..  =  (EF)../60D
           ID         ID
 where (EF)..  =  average emission factor for vehicle speeds about
                  0 mph, gm/min-veh, and other symbols are as defined
                  above

The emission factor (EF).. is the same as described in Section 4.4.2, so
                        ID
the value of 20 gm/min-veh for 1975 (from Figure 8) and the calculation

procedure for estimating the factor for years other than 1975 are

applicable.

4-5  Selection of Alternatives for Modeling

     The objective of the indirect source microanalysis is to determine

the highest 1- and 8-hour CO concentrations likely to occur at a reason-

able receptor site in the vicinity of a proposed development.  In making

this determination, several different alternatives that possibly require

separate modeling analyses should be evaluated:

        different wind directions must be input to produce maximum
        CO concentrations at different receptors;

        1-hour and 8-hour periods have different source emission
        rates and meteorological conditions;
                                   41

-------
        peak traffic periods and most adverse meteorological condi-
        tions may occur at different times of day.

        peak traffic volumes on access streets may not coincide with
        peak traffic movement periods in the parking area;

        CO concentrations at receptor sites without the impact of
        the proposed development (no-build alternative) may be of
        concern.

     Each of the above situations should be considered in preparing a

list of alternatives to be modeled for a specific indirect source anal-

ysis.  Some of the potential alternatives may drop out without perform-

ing a modeling analysis.  For example, if emission rates are 15 percent

higher during the peak traffic period than during the hour with worst

meteorology and wind speed is twice as high in the peak traffic period,

then it should be clear that the hour with worst meteorology would

produce the higher predicted CO concentrations, because the concentra-

tion is inversely proportional to wind speed.

     In some cases, there are no means of readily determining which

alternative will produce the highest predicted concentration without

running the alternatives in the HIWAY model.  The only input data that

are variables after the source-receptor configuration of the site has

been established are line source emission rates and meteorological data.

These data are input on only a few punch cards, so it may be advanta-

geous to make two or more runs with changes in a few data cards rather

than to include all alternatives in one run.  Another benefit of this

procedure is that it provides an opportunity for an interim review of

results.

     Analyses of 8-hour periods should be accomplished with relatively

high priority, since the 8-hour NAAQS of 10 mg/m   (9 ppm) for CO is
                                  42

-------
exceeded more often than the 1-hour NAAQS of 40 mg/m  (35 ppm).  If the




first run shows that the 8-hour standard is threatened but not the 1-hour




standard, further analysis of alternatives could focus exclusively on




8-hour periods.  Methods of estimating maximum 8-hour CO concentrations




with the HIWAY model are discussed in Chapter 7.
                                  43

-------
5.0  INPUT DATA FORMAT FOR THE HIWAY MODEL




     This chapter describes how the data generated per the instructions




in the .previous chapter are transformed into an input data card deck for




the HIWAY program.  The discussion concentrates on batch (card deck)




rather than interactive (computer terminal keyboard) operation because




the amount of data generally necessary for the indirect source analysis




would be too time-consuming to input with the interactive mode.




     A minimum of seven data cards are required for each line source in




the analysis.  Table 6 shows the sequence and format for these seven




types of input data cards.




     Note that all data, except the heading (card type 1) are in floating




point format with 10-space field widths.  It is crucial that a decimal




point be placed in each field.  Otherwise, the data will be misread and




results will be incorrect.  It is recommended that the data be left-




oriented in the fields, as shown in the columns titled "Forms," to




facilitate keypunching and verification.




    For indirect source analysis, many line sources (e.g., 10 to 50)




will probably be input as a single data set representing one time




period.  Also, more than one of these data sets of several sources may




be included in a computer run of the model.  Before the seven types of




data cards for another line source are placed in the deck, a card with




the value 9999. in columns 1 through 5 should be used to separate this




input data from the previous line source's data.  The same card should




be used between data sets for different alternatives.  The card with




9999. should not be used after the final set of line source input data.




     Data on card types 5, 6 and 7 are the same for all line sources in




a data set representing one time period.  Therefore, these cards can be





                                    44

-------
Table 6.  INPUT DATA FORMAT
Card/ input name
Type 1 (1 card)
Heading



Type 2 (1 card)
REP1
SEP1
REP2
SEP 2



H
WIDTH



CNTR


XNL


Type 3 (up to
3 cards)
QLS



Type 4 (1 card, -may
be blank
Columns

1-80




1-10
11-20
21-30
31-40



41-50
51-60



61-70


71-80




1-80





for at-grade)
CUT

WIDTC

1-10

11-20

Format

20A4




F10.0
F10.0
F10.0
F10.0



E10.0
F10.0



F10.0


F10.0




F10.0






F10.0

F10.0

Form

AAAA




XXXX.XXX
XXXX.XXX
XXXX.XXX
XXXX.XXX



XX. X
XX.



XX.


X.




.xxxxxxxx






X.

XX.

Description

Alphanumeric descrip-
tion of line source
segment & other inform-
ation (e.g., time pd.)

East coordinate, pt. 1
North coord. , point 1
East coord. , point 2
North coord., point 2
(end points of the
line source are at
centerline of road)
Height of source
Total width of road
incl. center strip
(not input for cut
section)
Width of center
strip (not input for
cut section)
Number of traffic
lanes



Emission rate for
each lane (in order
from left to right
viewed from pt. 1)



0. if at-grade
1. if cut section
Width of top of cut
section
Units

-




Map units
Map units
Map units
Map units



Meters
Meters



Meters


_




Gm/sec-m






-

Meters

Value
limits

-




-

-
-



0. or +
_



< width


1. or even
integer 2 .
to 24.


-






0. or 1.

_

            45a

-------
                     Table 6.  INPUT DATA FORMAT (continued)
Card/input name
Type 5 (1 card)
THETA
U
HL
XKST
Type 6 (1 card)
GS
Type 7 ( up to
50 cards)
XXRR
XXSR
Z
Columns
1-10
11-20
21-30
31-40
1-10

1-10
11-20
21-30
Format
F10.0
F10.0
F10.0
F10.0
F10.0

F10.0
F10.0
F10.0
Form
XXX.
XX. X
XXXX.
X.
X . XXXXXXX

XXXX . XXX
XXXX. XXX
XX.
Description
Wind direction, degrees
from north
Wind speed
Height of mixing layer
Pasquill stability
class:
A = 1. D = 4.
B = 2. E = 5.
C = 3. F = 6.
Scale factor for map
units:
kilometers =1.0
meters = 0.001
feet = 0.0003048
miles = 1.6093

East coordinate of
receptor*
North coordinate of
receptor
Height of receptor
Units
Degrees
M/sec
Meters



Map units
Map units
Meters
Value
limits
0.-360.
1.0 or
greater
>100
1. to 6.


-
-
0. or +
*A value of 9999. is entered in this field following the last receptor card
 if another set of data is to follow.
                                      45b

-------
 duplicated  to produce  the  appropriate number of copies  for compilation




 of  the  data deck.




      The  data cards  for  a  run  are  placed  behind the  HIWAY program  deck




 as  shown  in Figure 9.  Job control cards  for the  specific computer




 system  are  located at  the  front  of the  deck, between the HIWAY  program




 and input data  decks,  and  at the end of the input data.  The  program can




 be  run  on computers  that read  FORTRAN IV.




      The  computer CPU  time required to  run the program  is a  function of




 many factors, including  the number of sources  and receptors.  On an




 IBM 370 computer, about  17 seconds are  required to compile the  program




 plus about  0.2  seconds running time for every  source-receptor combina-




 tion.  For  example,  an analysis  with 20 sources and 12  receptor sites




 would take  about 65  seconds CPU  time  (17  + 20  x 12 x 0.2) on  this  computer.




 Depending on the number  of sources and  receptors, either a 3- or 5-




.minute  upper limit should  be specified  for an  IBM 370 in case of an




 error in  the input data.




      To simulate a different alternative, only the emission  rates  (card




 type 3) and/or  meteorological  conditions  (card type 5)  will  change.




 Type 3  and  type 5 cards  containing data for the second  alternative can




 be  manually inserted in  the deck,  replacing the corresponding cards from




 the first run.   The  revised deck is then  ready to be run again, although




 the printout from the  first run should  be reviewed for  errors or unexpected




 results before  the deck  is resubmitted.




      If the interactive  operation  of HIWAY through the  UNAMAP system is




 used for  an uncomplicated  analysis, the same  input data must be avail-




 able.  After the computer  is accessed,  the HIWAY  program  is  initiated by




 typing  the  command  "hiway." All communication by the user  is in lower





                                    46

-------
                    job control card  /
                  data  set for       f
                                          . U.MK a
            third line  source (/eRoA»w»y,u*»iK» *""" NE *
          spacer card
       data set for       A
       second line source^
     spacer card        £-

   card  types 7
  card type 6
 card type 5
card type 4
                                472.3.  1102.
                                            *.0
                             / o.ooo&o^a
                           / 04.5.  r*
     card  type 3
    card type 2
   card type 1
                          .0015
                                       .0095   .CO/ 7 .OOI1  .0019
 /'
                                      11*1.  O.0
/ FIPTH ST., LJfJfc »
                                     N« S PM
                           OATA
 job control cardiiy ^
 HIWAY
 program
job     x
control
cards
  Figure 9.   Assembly of  HIWAY card deck
                                      47

-------
case letters.  Input data are entered as the computer calls for them.




Result?-, are output after the data for each line source have been enter-




ed.  After the results are printed, options are available to run the




model for new receptor locations or a new road segment  (line source), or




to end the program.
                                    48

-------
6.0  OUTPUT DATA AND ITS PRESENTATION
     The model-calculated CO concentrations, in uq/m  and ppm, at all
specified receptor locations resulting from the traffic lanes of a
single line source are output in the format shown in Figure 10.  Notice
that the name assigned to the line source on input card 1 is printed as
the heading for the output for that data set, and that all other input
data are summarized above the tabular presentation of CO concentrations.
     The combined impact on any receptor site of all line sources in the
vicinity of the proposed development is determined by adding the concen-
trations contributed by each line source.  The same meteorological input
data must be used with every source in a data set representing the
combined effect of all sources.  A convenient tabular format for calcu-
lating total predicted CO concentrations at each receptor is shown in
Table 7.
     The impact of the nearby traffic considered in the model is usually
predominant at the specified receptor locations.  However, the total CO
concentration at any receptor would also have some contribution from
other, more distant traffic, commonly referred to as the urban back-
ground component.  As indicated in Table 7, a value representing the CO
background should be added to the model-predicted concentrations at each
receptor site before these estimated total concentrations are compared
with the National Ambient Air Quality Standards  (NAAQS).
     Several approaches for estimating background concentrations,
depending on what data are available, are described in Section 4.3 of
the Guidelines and in Appendix H of the Guidelines.  The approaches are
summarized below, but it is recommended that the full descriptions from
the original references be reviewed before calculating background con-
centrations .
                                   49

-------
	HI WAY VERSION:
 EN DP 01 NTS OF
              THE  LINE SOURCE
               .220  ANC      ,<»15
                                          IPO
EMISSION
EMISSION
          HEIGHT TS     .COP METERS
          RATE ( GRAKS /S ECOVD* METF R)
          OF
                                 1 LANECS)
     .300-02
 WT3TH OF AT-GRADE
 WIDTH
 WIND
                    HIGHWAY TS
          5.0 M
       OF  CENTER
      DIRECTION
       .0
DEGREES
WIND SPEED I
STABILITY
HEIGHT  OF
THE  SCALE
       STRIP IS
       S	10.	
       i.o METCpr/src
CLASS  TS     4	
LIMITING  Lib" IS   Z CD 0.0 METERS
OF THE COORDINATE AXES IS	l.OCDC USER UNTTS/KH.
RECEPTOR
X
.2C50
.3350
.7850
.tZOQ
.4650
.5B50
.8850
.3375
.2000
.2000
.9000
LOCATION
Y
-.OC75
-.0075
-.CC75
-.0075
-.CC75
-.0075
-.G075
-.0125
-.0125
.2200
-.0125
HEIGHT
Z( M)
Z. GOOD
2. OC 00
2. CD 00
2. CO CD
2. 00 00
2.CCOO
2. CD 00
2. CO 00
2. CDOC
2. OCOO
2. 00,00
CONCENTRATION
UGM/MET[IR**3
0.
27.
87 7
J *J •
59.
0.
0.
0.
612.
0.
0.
r.

PPM *
.000
• 02«»
.725
.052
.noo
.pro
.CPO
.532
• OPO
.ono
.ono
*   PPM CONCENTRATIONS CORPfCT FCR CARSON MONOXIDE ONLY.
 Figure 10.  Example HIWAY output
                             50

-------
    Table 7.  CALCULATION OF TOTAL CO CONCENTRATIONS AT RECEPTOR SITES
Hour of Day




Season
Wind Direction
Wind Speed, m/sec




Mixing Height, m	




Stability Class	
Receptor No.
Receptor
Coordinates
Line Source

Subtotal , ppm
Estimated Back-
ground , ppm
Total Concen-
tration , ppm










CO Concentration, ppm




















                                   51

-------
Approaches for Estimating Background Concentrations

     1.  Note the second highest 1- and 8-hour concentrations observed

at a continuous monitoring station near the site of the proposed source

over the past year during the time period of concern.  These values

should be adjusted to account for the effect that the Federal Motor

Vehicle Emission Control Program will have by the first year of the

proposed source's operation.

     2.  Use results of a calibrated mesoscale diffusion model such as

APRAC-1A to estimate the highest representative 1- and 8-hour concen-

trations likely to occur during the time period of concern.

     3.  If ambient sampling data for a limited period (assumed to be 14

days) at the proposed site plus a full year's data by hour for another

site in the urban area  (located at least 100 meters from major traffic

lanes) are available, the background  (x ) may be calculated as follows:
          Max. observed l-hr/8-hr cone.
          at proposed site during oper-
          ating hours
 Max. observed l-hr/8-hr cone.
 at historical site during
 source operating hours in
_past year
                         Max. observed l-hr/8-hr cone.
                         at historical site during
                         source operating hours during
                        _the limited sampling period  _
     4.  If ambient sampling data for a limited period at the proposed

site plus maximum observed concentrations at another site in the urban

area are available, the background may be calculated as follows:
                                    52

-------
         fMax. observed l-hr/8-hr cone.
          at proposed site during oper-
         [ ating hours
Max. observed l-hr/8-hr cone."
at historical site during
past year
                         Max. observed l-hr/8-hr cone.
                         at .historical site during
                         the limited sampling period
     5.  If only ambient sampling data for a limited period at the pro-

posed site are available, the background may be calculated as follows:
          Max. observed l-hr/8-hr cone.
          at proposed site during oper-
          ating hours
Max. X/Q in site's locale
for any season from Figures
42 - 45 of AP-101
                        "X/Q" in site's locale from Figures
                         42 - 45 of AP-101 during time of
                         year in which sampling is performed
      6.  If the source is to be located in a rural area, a natural back-

ground of 1 ppm may be assumed.



     For each time period and set of meteorological conditions simulated,

a different CO concentration is predicted at any given receptor site.  The

maximum concentration, including background, predicted at a receptor site

under any alternative is compared with the 1-hour NAAQS of 40 mg/m

(35 ppm) or 8-hour NAAQS of 10 mg/m  (9 ppm) as the final step in the

indirect source analysis.  If one or more of the predicted concentrations

exceed the NAAQS, the proposed source's application may not be approved

until its traffic handling facilities have been redesigned so that NAAQS

can be met.
                                  53

-------
7.0  ESTIMATION OF MAXIMUM 8-HOUR CO CONCENTRATIONS

     In most instances, peak 8-hour CO concentrations are more likely to

exceed the NAAQS than are peak 1-hour concentrations.  However, there is

presently no completely satisfactory procedure for estimating peak 8-

hour concentrations, since the HIWAY model is designed to accept input

data for 1-hour averaging periods.

     The procedure described in Section 4.2 of the Guidelines  for

estimating peak 8-hour concentrations is to manually modify predicted 1-

hour concentrations by applying a persistence factor.  The persistence
                 *
factor, which is always less than 1.0, accounts for variations in meteor-

ology  (primarily in wind direction) occurring over an 8-hour period as

opposed to a 1-hour period.

     The other modification necessary to predict peak 8-hour concen-

trations by the persistence factor procedure is to input emission rates

consistent with the mean hourly traffic volume during the 8-hour period

of concern rather than peak 1-hour emission rates.  The mean traffic

volume for the 8-hour period is always less than peak 1-hour volume.

     A method for calculating an appropriate meteorological persistence

factor from concurrent wind data, CO sampling data, and traffic data at

a site "similar" to the proposed one is also presented in Section 4.2 of

the Guidelines.

     The persistence factor is calculated as follows:

     a.   Select an existing indirect source similar to the proposed

one.

     b.   Concurrently monitor hourly traffic volume, wind speed, wind

direction, and CO concentrations.


                                   54

-------
     c.   Note the highest 1-hour CO concentrations (with wind speed
<2m/sec) and traffic volume during that hour for each day.
     d.   Note the highest 8-hour average CO concentration and average
hourly traffic volume during that period for each day.
     e.   Calculate a persistence factor, p, for each day:
                     (Max. 8-hr av. CO)             Vl
               P  =
                     (Max. 1-hr. CO with u<2m/sec) V
                                                     8
     f.   Select the highest observed daily persistence factor for
estimating maximum 8-hr CO concentrations.
     The steps involved in estimating peak 8-hour concentrations are
summarized below:
     1.   Determine the mean hourly traffic volumes and emission rates
on each traffic lane for the 8-hour period of interest.
     2.   Determine the meteorological input data for the peak 1-hour
emission period during the 8 hours according to the instructions out-
lined in Section 4.3 of this document.
     3. ,  Run the HIWAY model with the emission and meteorological input
data obtained in steps 1 and 2.
     4.   Multiply predicted concentrations at each receptor site by the
calculated persistence factor to account for lack of persistence in the
adverse meteorological conditions.
     5.   Add a background concentration for the 8-hour period, calcu-
lated by one of the approaches described in Chapter 6, to the predicted
concentrations to determine the estimated peak 8-hour concentrations for
comparison with the NAAQS of 9 ppm.
     In addition to the procedure based on a persistence factor relating
1-hour and 8-hour concentrations, several other procedures for estimating
                                 55

-------
peak 8-hour concentrations at proposed developments are discussed in


Appendix H of the Guidelines.  All of the procedures are empirical in


that they require analysis and application of wind data and/or air


quality data from the proposed development site or a similar location.


     Two of these alternate procedures are:


     1.  Using predicted maximum hourly traffic volumes for an 8-hour


period and observed adverse meteorological data on an hourly basis for


that same time period, run the HIWAY model eight times to simulate the


successive 1-hour concentrations.  Peak 8-hour concentrations can then


be obtained by averaging these eight values.


     2.  Using wind speed and direction observations for the peak 8-hour


emission period/ construct conditional hourly wind direction change

                       Q
frequency distributions  for those periods with low wind speeds.  These


wind direction change frequency distributions can then be input to a


simulation of the proposed site in which receptors are strategically


placed, and the simulation repeated with several sets of wind direction


change data.  To estimate peak 8-hour concentrations for comparison with


NAAQS, the highest ratio between estimated 1-hour and 8-hour concentra-


tions at each receptor should be used.


     It should be emphasized that these procedures do require collection


of wind speed and direction data at a location that is determined to be


representative of the proposed site.  Any of these three procedures for


estimating peak 8-hour concentrations can be used if the necessary data


are available and if applied appropriately.
                                   56

-------
                                  REFERENCES


 U.S. Environmental Protection Agency, Office of Air Quality Planning and
 Standards; "Guidelines for the Review of the Impact of Indirect Sources
 on Ambient Air Quality"; EPA-450/4-74-010; (January 1975);  Research
 Triangle Park, N. C. 27711.
2
 Zimmerman, J. R. and R. S. Thompson; "User's Guide for HIWAY: A Highway
 Air Pollution Model"; Environmental Monitoring Series EPA-650/4-008;
 (February 1975); National Environmental Research Center, U.S. Environ-
 mental Protection Agency, Research Triangle Park, N. C. 27711.

 American Association of State Highway Officials; "A Policy on Geometric
 Design of Highways in Urban Areas";  (1957); Washington, D.  C.
4
 U.S. Environmental Protection Agency, Office of Air Programs; "Mixing
 Heights, Wind Speeds and Potential for Urban Air Pollution Throughout
 the Contiguous United States"; Office of Air Programs Publication Number
 AP-101; (January 1972); Office of Technical Information and Publications,
 Research Triangle Park, N. C. 27711.

 Turner, D. B.; "Workbook of Atmospheric Dispersion Estimates"; PHS Publi-
 cation No. 999-AP-26; (1969); U.S. Environmental Protection Agency,
 Research Triangle Park, N. C. 27711.
6
 U.S. Environmental Protection Agency; "Compilation of Air Pollutant
 Emission Factors"; Publication Number AP-42; Supplement No. 5 to the
 Second Edition; (April 1975) ; Office of Technical Information and
 Publications, Research Triangle Park, N. C. 27711.
7
 Kunselman, P., H. T. McAdams, C. J. Domke and M. Williams;  Automobile
 Exhaust Emission Modal Analysis Model;  (January 1974); U.S. Environmen-
 tal Protection Agency, Ann Arbor, Michigan.
8
 Meyer, E.  L., Jr., and J. E. Quon; "A Method for Simulating Wind Con-
 ditions During Atmospheric Stagnation Periods"; J. Appl. Met. 11;
 (August 1972).
                                   57

-------
                           APPENDIX.  EXAMPLE ANALYSIS









Problem.  A regional shopping center of 780,000 square feet leasable




floor space and 3800 parking spaces is to be built in a Southeastern




metropolitan area.  Completion is expected by January 1978.  A plan of




the proposed shopping center and surrounding area is shown in Figure




A 1.




     Traffic volumes on access streets and at entrances/exits to' the




parking lot for a peak shopping period have been projected by the




developer with input from the Highway Department.  Estimated traffic




demand by hour for each access street and entrance/exit is shown in




Table A 1.  Average speeds by hour on the access streets are shown in




Table A 2.  During the peak seasonal shopping period, it is estimated




that ambient temperature would be approximately 50  F and that about 30




percent of the vehicles in the parking lot  (20 percent on the access




streets) would be operating from a cold start.  Traffic in the parking




area and on 68th and Mill Streets will be about 88 percent light-duty




vehicles, 12 percent light-duty trucks.  On other streets and highways,




the split will be about 80 percent LDV, 12 percent LDT, and 8 percent




heavy-duty truck  (assume negligible diesel-powered trucks).  Extensive




queuing is anticipated at two signalized intersections—Florida Boulevard




at Irving Boulevard and at Mill Street.  Queuing will probably also




occur at the non-signalized intersection at 68th Street and Irving




Boulevard.  The approximate signal times for the signalized intersections




and approach capacities for the non-signalized intersection are summarized




in Table A 3.




                                    58

-------
     Scale 1" = 250 feet
  •H
  U
  o
  U
                                       N
                                    INTERSTATE 85
                                                                                    - 3000
                                                                                   v- 2500
                 8
   Irving Blvd. 1
                                           B
                            .   F
                                                11
                 10
                                                                                    -2000
                                                                                Mill St.
                                                           R5     R4
                                                       12
                                              L
                                                                         CN
                                                I
                                                CQ

                                                (8
                                                •O
                                                •rl
                                                M
                                                O
                                                    R2
                                                                                    -1500
      Irving Blvd. 2:
                              Irving Blvd. 3
              R6
  I
3000
3500
  I
4000
  Figure A 1.  Proposed  shopping center and surrounding area



                                         59
CQ

n)
T)
•H

0
rH
fe
•RI
I
4500
                                                                                    _1000

-------
                                Table A 1.  TRAFFIC  DEMAND  BY  HOUR ON PEAK TRAFFIC  DAYS

-------
                        Table A 1 (continued).   TRAFFIC DEMAND BY HOUR ON PEAK TRAFFIC DAYS
Hour
Beginning
7 a.m.
8
9
10
11
12 noon
1 p.m.
2
3
4
5
6
7
8
9
10

Mill,
E
40
60
60
50
30
80
90
70
80
140
200
180
160
100
90
80

Mill,
W.
160
200
130
70
60
110
90
70
80
60
80
180
200
60
50
30

1-85,
E
3410
2600
2520
2250
2280
2770
2590
2600
3180
4350
4600
2160
1880
1470
1750
1210

1-85,
W
3850
4220
3160
2100
2350
2920
2480
2740
2660
3390
2700
1690
1950
1520
1300
980
Traffic
Ramp A,
E
130
100
90
80
90
120
110
100
150
210
280
120
80
50
60
40
demand ,
Ramp B,
E
60
90
40
30
30
30
50
40
30
100
80
100
70
110
80
20
vehicles/hour
Ramp C,
80
120
100
50
40
40
80
100
160
240
250
90
90
50
40
30
East
ent.
0
20
450
260
450
710
510
320
260
390
580
770
840
450
320
130
East
exit
0
0
190
130
260
640
710
390
190
320
450
510
580
770
770
510
South
ent.
0
0
130
70
130 .
.210
150
90
70
110
170
220
240
130
90
40
South
exit
0
0
60
40
70
190
210
110
60
90
.130
..150
170
'220
220
150
S.W. S.W.
ent. exit
0 0
10 0
240 100
140 70
240 140
370 340
270 370
170 200
140 100
200 170
310 240
410 270
440 310
240 410
170 410
70 270
E = eastbound
W = westbound
N = northbound
S = southbound

-------
Table A 2.  AVERAGE SPEEDS ON ACCESS STREETS
Street
Irving Boulevard,
all sections
68th Street
Mill Street
Ramps A, B, and C
1-85, eastbound

1-85, westbound

Florida Boulevard,
sections 1 and 2

Florida Boulevard,
section 3

Lanes
4
2
2
1
3

3

4

4

Time period
All hours
All hours
All hours
All hours
All hours except
those listed
7-8 a.m.
3-4 p.m.
4-5 p.m.
5-6 p.m.
All hours except
those listed
7-8 a.m.
8-9 a.m.
9-10 a.m.
4-5 p.m.
All hours except
those listed
7-8 a.m.
8-9 a.m.
12-1 p.m.
4-5 p.m.
5-6 p.m.
All hours except
those listed
8-9 a.m.
5-6 p.m.
Average speed, mph
25
20
20
35
50
42
43
34
27
50
39
36
43
42
30
27
26
28
24
24
30
27
27
                  61

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                    Table A 3.  DATA ON INTERSECTION DESIGNS
Intersection
Florida and
Irving Boulevards


;' < ! ' f
Florida Boulevard
and Mill Street


Irving Boulevard
and 68th Street


Approach
northbound
southbound
eastbound
westbound
:., ,:.,.•
northbound
southbound
eastbound
westbound
northbound
southbound
eastbound
westbound
	 .._.
Green time
to signal
cycle ratio
0.67
0.67
: 0.33
0.33

0.67
0.67
0.33
0.15




Cycles
per hr
* 40




40







Capacity,
veh/hr









600*
900
1400
1400
 Estimated at half of lane capacities assuming traffic in each direction
has right of way half the time.
                                   62

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     Based on tenant location, the developer predicts that the building




entrances will attract the following percentages of the center's customers:




          Building entrance        Percent of customers entering




                  A                              20




                  B                              16




                  C                              12




                  D                              11




                  E                              14




                  F                               6




                  G                              20




                  H                               1




     Meteorological data recorded at a nearby airport representative of




the shopping center location indicated that the average wind speed was




2.0 m/sec or less in 380 of the hours between 9 a.m. and 11 p.m. during




the past year.  In the same time periods, wind speed was 1.0 m/sec or




less in 131 hours.  Wind directions and stability classes corresponding




to the hours with wind speed - 1.0 m/sec are shown in Tables A 4 and




A 5, respectively.




     Ambient CO sampling has been conducted for a two week period on the




proposed site (near the coordinates 3600, 1800).  The maximum observed




CO concentration during that time was 2.5 ppm, from 6 to 7 p.m. on




Friday.  The maximum 8-hour concentration during source operating hours




was 1.8 ppm, from 3 to 11 p.m. on Friday.  CO sampling data are also




available for another suburban shopping center site in the same city.




The maximum 1- and 8-hour values recorded at that similar site on several




days throughout the past year are summarized in Table A 6.






                                  63

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  Table A 4.  WIND DIRECTIONS DURING HOURS WITH
               WIND SPEED OF 1.0 M/SEC OR LESS
Wind direction,
degrees from north
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
Number of annual
occurrences, hours
2
4
0
0
0
. ,. 3
' 1
• 1
0
1
2
4
3
3
0
0
3
7
9
7
14
5
4
4
4
3
3
4
7
12
8
5
2
4
1
1
Total                        131
                    64

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                   Table A 5.     NUMBER OF ANNUAL OCCURRENCES
                               OF WIND SPEED - 1 M/SEC BY HOUR OF
                               DAY AND CONCURRENT STABILITY CLASS
Hour
Beginning
9 a.m.
10
11
12 noon
1 p.m.
2
3
4
5
6
7
8
9
10
Total
Stability
ABC
2
1
1 1
2
2 1
2
1 1
2 3
3
3




8 17 0
Class
D E F
4
5
4
2
4
3
3
4
9
10
12 1
10 3
13 2
14 3
97 9 0
Total
6
6
6
4
7
5
5
9
12
13
13
13
15
17
131
 Daytime stability classes estimated from Table 5, p. 35.  Nighttime
stability estimated to be D if sky cover - *t, and E if < ^ because of
suburban location.
                                    65

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              .Table A 6.  MAXIMUM 1- AND 8-HOUR CO CONCENTRATIONS
                          AT AN EXISTING SUBURBAN SHOPPING CENTER
Date
Jan.
Jan.
Feb.
Feb.
Feb.
Apr.
Jun.
Jun.
Jun.
Sep.
Sep.
Sep.
Oct.
Nov.
Nov.
Nov.
Dec.
Dec.
Dec.
Dec.
Dec.
Dec.

19
23
1
23
26
19
7
8
12
14
20
30
5
6
22
23
6
7
14
17
20
21
Max. 1-hour
CO, ppm*
18.0
15.5
12.1
14.6
15.8
20.1
10.9
14.5
15.1
16.0
15.5
12.8
16.5
16.5
11.7 .
19.0
16.5
16.1
21.3
26.6
23.2
27.7
Time period
1600-1700
1900-2000
1600-1700
1100-1200
1700-1800
1700-1800
2000-2100
1200-1300
1600-1700
1600-1700
1700-1800
1700-1800
1100-1200
1700-1800
1800-1900
1600-1700
1900-2000
1200-1300
1400-1500
1600-1700
1700-1800
1700-1800
Max. 8-hour
CO, ppm
8.8
7.0
7.3
6.5
9.3
12.0
6.5
8.5
9.1
9,0
8.1
7.7
8.5
9.9
6.8
11.1
7.2
9.4
10.7
12.8
13.0
12.9
Time period
1300-2100
1500-2300
1300-2100
1000-1800
1400-2200
1500-2300
1500-2300
1100-1900
1500-2300
1000-1800
1500-2300
1400-2200
1100-1900
1500-2300
1400-2200
1200-2000
1300-2100
1200-2000
1300-2100
1500-2300
1400-2200
1400-2200
Wind speeds during these hours were - 2 m/sec.
                                  66

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     Determine whether the traffic associated with the proposed shopping




center will cause either.CO standard to be exceeded and, if so, where




the expected violations will occur.









Solution. The steps in this solution follow those outlined in Figure 1.




Many of the initial steps shown in Figure 1 have already been completed




as part of the problem description.




     1.   Select time periods and alternatives for analysis.  By reviewing




the traffic volume and speed data, it can be determined that the highest




emission rates in the vicinity of the shopping center will probably




occur between 5 and 6 p.m., as a result of heavy commuter traffic on




access streets.  The meteorological data in Table A 5 indicate that the




most adverse conditions for dispersion  (E stability) are likely to occur




from 8 to 11 p.m.  Therefore, both the 5 to 6 p.m. and 8 to 9 p.m.




periods should be analyzed as possible peak 1-hour periods.




     Depending on which of those two hours shows the highest CO concen-




trations, either the 12 noon to 8 p.m. or 3 p.m. to 11 p.m. 8-hour




period will be used to calculate the maximum 8-hour concentration.  The




noon to 8 p.m. period has the highest traffic volumes and the 3 to 11




p.m. period has the most hours of E stability.




     The peak traffic season for which the traffic data are applicable




is December, which coincides with the time of year with highest proba-




bility for low wind speeds and stable atmospheric conditions.  There-




fore, no other seasonal conditions need to be analyzed.  The year to be




simulated in the analysis should be 1978, the first year that the




shopping center will be open.





                                    67

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     2.   Determine emission factors.  The emission factor for movement
in the parking lot can be calculated by adjusting the value obtained
from Figure 8 for year, ambient temperature, and percent of vehicles
operating from a cold start.  An average speed of 10 mph is assumed in
the parking lot.
          (EF)_0 = (EF)__ (ef/55) (factor for 50° F, 30% cold start)
              /O       / D
                 = (19.0) (35/55) (1.6)
                 = 19.3 gm/min-veh
The correction factor of 1.6 is obtained from Table 1 of the Guidelines.
     Additional calculations are required to determine emission factors
for access streets because of the different speeds for each link and the
heavy-duty vehicles present.  These factors are summarized in Table A 7.
The HDV emission rate, 56.4 gm/min at 18 mph, must be calculated from
                          6
Supplement No. 5 of AP-42.
     3.   Calculate total emissions for parking lot.  Emissions are
estimated from the equation:
                 fe .(EF)  (V)  (RT)
               y      216,000
The emission factor, EF, was determined in step 2 above.  Traffic
volume, V, is the sum of all vehicles either entering or leaving the
parking lot during the time period.  According to the data in Table A 1,
the values for V in veh/hr are:
                5 to  6 p.m. -  1880
                8 to  9 p.m. -  2220
               12 to  8 p.m. -  1856
                3 to 11 p.m. -  1782
Base running time for movement into and out of a parking space has been
                                    68

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                 Table A 7.  EMISSION FACTORS FOR ACCESS STREETS
                                                  Emission factor, with
Average speed, mph        Street section           8% HDV, gm/min-veh
     50              (1-85 E and W, 8-9 p.m.             17.2
                      1-85 W, 5-6 p.m. and
                      12-8 p.m.)
44
35
30
28
27
25
24
20
(1-85 E, 12-8 p.m.)
(Ramps A, B, and C)
(Florida Boulevard 1, 2,
and 3, 8-9 p.m.)
(Florida Boulevard 1 and 2,
12-8 p.m.)
(Florida Boulevard 3 and
1-85 E, 5-6 p.m.)
(Irving Boulevard)
(Florida Boulevard 1 and 2,
5-6 p.m.)
(68th Street, Mill Street)
17.4
18.2
18.9
19.3
19.5
19.9
20.0
15.0
(0% HDV)
The above factors are based on 50° F temperature and 20 percent of
vehicles operating from a cold start in 1978.
                                   69

-------
estimated at 130 seconds.  There should be no extra running time due to




congestion during the 5 to 6 p.m. period because the parking lot is only




about 25 percent (960/3800) full at the beginning of the hour.  Accumu-




lation in the parking lot is also less than the 80 percent full level at




which running times start increasing appreciably at 8 p.m.  Therefore,




the base running time can be used for all time periods of interest, and




emissions are estimated as follows:




                5 to  6 p.m. -  21.8 gm/sec




                8 to  9 p.m. -  25.8




               12 to  8 p.m. -  21.6




                3 to 11 p.m. -  20.7




     4.   Distribute emissions to lanes in parking lot.  Using the pro-




cedure presented in Section 3, the parking lot emissions can be allo-




cated to the 12 major traffic links identified in Figure A 1.  The




calculations for this distribution and the resulting line source emission




rates for the 5 to 6 p.m. period are summarized in Table A 8.  For other




time periods, emission rates by link are proportioned to total parking




lot emission rate for the period compared to the 5 to 6 p.m. period.




     5.   Calculate emission rates for access streets.  Emissions rates




can be determined directly by use of the equation presented in Section




4.4.2, page 37.  In order to obtain the emission rates per lane, the




calculated value must be divided by the number of lanes carrying traffic




in the given direction on the street.  The emission rates are shown in




Table A 9.




     6.   Calculate lengths and emission rates for queues.  Using the




two equations on page 23 and data from Table A 3, queue lengths during






                                   70

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Table A 8.  ALLOCATION OF PARKING LOT EMISSIONS TO TRAFFIC LINKS
Traffic
link
1
2
3
4

5

6

7

8 "
9
10
11
12

Length ,
feet
250
110
520
520

110

720

880

280
520
280
190
350

Fraction of entering or exiting
vehicles using this link
(.55) .55
(.55) (.6) .33
(.55) (.3) .16
(.55) (.6) (.6)+ (.16) (.4) (.8) (.7)+ .29
(.29) (.6) (.5) (.8) (.7)+(.29) (.3) (.6) (.2)
(.55) (.6) (.6) (.2) +(.55) (.3) (.3) +(.16) (.4) (.8) (.7) (.1)+
(.29) (.6) (.5)(.8)(.7)(.2) .10
(.55) (.6) (.6) (.4) +(.55) (.3) (.3) (.8) +(.29) (.3) (.6)+
(.16) (.4) (.8) (.7) (.3)+ (.29) (.6) (.5) (.8) (.7) (.3) .20
(.55) (.6) (.6) (.4) (.3)+(.55) (.3) (.3) (.8) (.3)+ .16
(.29) (.3)+ (.16) (.3) (.4)+ (.55) (.6) (.4) (.4) (.9) (.3)
(.29) .29
(.55) (.6) (.4) (.4) (.9)+(.29) (.6)+(.16) (.3) .27
(.16) .16
(.55) (.6) (.4) (.4)+(.29)(.6) (.5)+(.16) (.4) .20
(.55) (.6) (.4)+(.29) (.6) (.5) (.8)+(.16) (.4) (.8) .25

Weighting
factor
137
36
83
151


11

144
141

81
140
45
38
88
1095
Line source
strength, g/s-m
.0359
.0215
.0104
.0189


.0065

.0131
.0104

.0189
,0176
.0104
.0131
.0163

Emission rate by
lane, gm/sec-m
5-6 p.m. ,
south or
east lane
.0078
.0094
.0059
.0106


.0033

.0061
.0055

.0106
.0091
.0059
.0069
.0082

5-6 p.m. ,
north or
west lane
.0101
.0121
.0045
.0083


.0032

.0070
.0049

. 0083
.0085
.0045
.0062
.0081


-------
Table A 9.  EMISSION RATES BY LANE FOR ACCESS STREETS
Street
Irving 1
Irving 2
Irving 3
68th Street
Florida 1
Florida 2
Florda 3
Mill Street
1-85
Ramp A
Ramp B
Ramp C
Direction
eastbound
westbound
eastbound
westbound
eastbound
westbound
northbound
southbound
northbound
southbound
northbound
southbound
northbound
southbound
eastbound
westbound
eastbound
westbound
eastbound
eastbound
SE-bound
NW-bound
Emission
5-6 p.m.
.0054
.0019
.0049
.0020
.0035
.0014
.0011
.0016
.0079
.0101
.0087
.0101
.0048
.0063
.0016
.0006
.0115
.0032
.0015
.0004
.0013
.0013
rate for
8-9 p.m.
.oois
.0031
.0014
.0024
.0014
.0017
.0004
.0005
.0028
.0037
.0029
.0042
.0023
.0026
.0008
.0005
.0017
.0018
.0003
.0006
.0003
.0003
each lane,
12-8 p.m.
.0032
.0019
.0030
.0018
.0021
.0013
.0010
.0011
.0055
.0058
.0056
.0059
.0032
.0036
.0010
.0008
.0041
.0030
.0008
.0003
.0007
.0007
gm/sec-m
3-11 p.m.
.0030
.0021
.0028
.0019
.0010
.0014
.0008
.0009
.0043
.0054
.0046
.0055
.0028
.0033
.0010
.0007
.0035
.0024
.0007
. 0004
.0006
.0006
                      72

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peak traffic hours can be estimated.  For signalized intersections,




traffic volume (V) should be per lane.  For the significant queues




(greater than 25 meters in length), emission rates over the queue length




are then estimated with the equations in Section 4.4.3.  These calcula-




tions are summarized in Table A 10.




     7.   List all line sources, record the grid coordinates of their




end points, and obtain other dimensions.  As indicated in the previous




steps of this analysis, there will be 12 access street links, 12 major




traffic aisle links in the parking lot, and eight queues.  End point




coordinates are scaled from Figure A 1 and other dimensions should be




obtained from the developer and/or a site visit.  These data are pre-




sented in Table A 11.




     8.   Select receptor sites.  Receptor sites should be specified at




locations near the highest line source emission rates, in directions




that are normally downwind of these sources during the periods with




adverse meteorology, and at points where the general public is likely to




have access for 1- or 8-hour periods.  With these criteria, receptors on-




the east side of Florida Boulevard are likely to have the highest CO




concentrations in the vicinity of the shopping center.  Due to the




right-of-way areas on both sides of 1-85, no potential receptor sites




can be found near this highway even though it has high emission rates.




     For this shopping center, the traffic aisles in the lot are shown




to have approximately the same emission rates as the access streets.




Therefore, receptor sites should be specified at reasonable locations in




or adjacent to the lot.  One receptor should be established near the




main (east) gate of the shopping center because of the potential queues





                                   73

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Table A 10.  QUEUE LENGTHS AND EMISSION RATES
Intersection
Florida and
Irving Boulevards


Florida Boulevard
and Mill Street


Irving Boulevard
and 68th Street


Approach
northbound
southbound
eastbound
westbound
northbound
southbound
eastbound
westbound
northbound
southbound
eastbound
westbound
Queue length , meters
5-6 p.m.
60
77
80
23
67
82
30
14
1
1
109
2
8-9 p.m.
29
43
24
28
29
40
52
10
0
3
30
2
Emission rate, gm/sec-m
5-6 p.m.
.0084
.0085
.0149
.0136
.0085
.0085
.0136
• —
__
—
.0425

8-9 p.m.
.0068
.0078
.0136
.0136
. 0068
.0078-:
.0142-
—
__
—
.0425
—
                74

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                  Table A 11.   CONFIGURATION OF LINE SOURCES
Line source
Access streets
Irving 1
Irving 2
Irving 3 .
68th Street
Florida 1
Florida 2
Florida 3
Mill Street
1-85
Ramp A
Ramp B
Ramp C
Parking lot aisles
1
2
3
4
5
6
7
8
9
10
11
12
Queues
F lor ida/I r ving-
northbound
southbound
eastbound
westbound
Florida/Mill-
northbound
southbound
eastbound
Irving/68th-
eastbound
End point coordinates, ft.
Xl Yl Xz Yz

2500
3358
4444
3358
4444
4444
4444
4444
2500
4018
4505
4500

4174
4067
4174
4067
4067
3358
3358
3358
3358
3877
3877
4067


4462
4426
4413
4475

4462
4426
4399

3343

1119
1119
1119
700
700
1119
1782
1782
2650
2557
2217
2548

1776
1776
1776
1776
2302
2302
1425
1119
1425
1119
1425
1425


1092
1147
1105
1133

1751
1801
1763

1105

3358
4444
5000 -
3358
4444
4444
4439
5000
5000
4340
5125
4668

4444
4174
4174
4067
4174
4067
3358
3358
3877
3877
4067
4067


4462
4426,
4151,
4550

4462
4426,
4300
*
2985

1119
1119
1119
1119
1119
1782
3200
1782
2650
2443
2565
2338

1776
1776
2302
2302
2302
2302
2302
1425
1425
1425
1425
1776

*
895,
1400
1105
1133
*
1531,
2070
1763

1105
Width of
road., m

16.5
16.5
15.9
7.2
18.9
18.9
27.4
7.1
45.7
4.2
4.2
8.4

15.3
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.2
7.2


4.0
4.0
4.1
4.1

4.0
4.0
3.7

4.1
Width of
median, m

0
0
0
0
3.0
3.0
3.0
0
17.7
0
0
0

0.7
0
0
0
0
0
0
0
0
0
0
0


0
0
0
0

0
0
0

0
Number of
lanes

4
4
4
2
4
4
6
2
6
1
1
2

4
2
2
2
2
2
2
2
2
2
2
2


2
2
2
2

2
2
2

2
For 5 to 6 p.m.
other hours.
period; queue length and end point are different for
                                  75

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at this exit.  The highest queue emission rate is at the eastbound



Irving Avenue approach to the intersection with 68th Street.  Therefore,



a receptor should also be specified at the nearest reasonable location



to this intersection approach.



     The probable critical receptor sites at this proposed development



are shown in Figure A 1.  Their grid coordinates, summarized in Table



A 12, have been calculated based on the street dimensions presented in



Table A 11 and reasonable distances away from the curbs.



     9.   Specify wind speed, mixing height, and stability class for



each time period.  Based on the data in Tables A 4 and A 5, wind speeds



of 1.0 m/sec or less occur in conjunction with most wind directions and



during all hours that the shopping center will be in operation.  There-



fore, this wind speed should be used in the analysis for all alterna-



tives.  As discussed above, D stability class is the most adverse



condition likely during the 5 to 6 p.m. period and E stability is the


                                                              4
most adverse for the 8 to 9 p.m. period.  Reference to AP-101,  Figure



7, indicates that the mean winter afternoon mixing height for the



metropolitan area in which the shopping center is located is 1000



meters.  Mixing height for the 8 to 9 p.m. period is estimated to be



midway between the morning (minimum) mixing height of 400 meters and the



afternoon mixing height.  Thus, the approximate 8 to 9 p.m. mixing



height is 700 meters.



     io.  Select wind directions.  Wind directions which put the line



sources and queues upwind of the receptors plus wind directions nearly



parallel to the major line sources should be considered.  These
                                   76

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                      Table A 12.  RECEPTOR SITE LOCATIONS
Receptor site
  Coordinates, ft.
  x             y
                     Height, m
     R 1

     R 2

     R 3

     R 4

     R 5

     R 6
4483

4498

4505

4350

4200

3275
1080

1723

2122

1748

1748

1086
2

2

2

2

2

2
                                     77

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conditions can both be met for the five receptor sites by analysis of

three different wind directions—200 , 290 , and 330 .

     11.  Code input data and run HIWAY model.  In order to model the

alternatives described above, 12 different data sets must be run: four

different emission rates times three wind directions.  Three different

computer runs of the program will be made, one for each wind direction.

     12.  Tabulate and total the model-predicted concentrations at each

receptor.  The contribution from each of the 32 sources in each of the

12 alternatives can be recorded in a tabular format such as presented in

Table 7, page 51.  The subtotals (minus background) at the six receptor

sites under each alternative are summarized in Table A 13.

     13.  Determine persistence factor for 8 hours.  Using the equation

presented in the Guidelines, the persistence factor can be calculated as

follows:
             _   (Max. 8-hr average concentration)    f  1
                 (Max. 1-hr concentration with wind   \V
                 speed < Z m/sec)                      8

    where V  =  traffic volume demand during hour in which highest
                CO concentration was observed

          V  =  average hourly traffic volume demand during 8-hour
                period in which highest CO concentrations were
                observed

Due to lack of concurrent traffic and CO data at the similar site, it is

assumed that average traffic demand during the 8 hours is the same as

during the hour with highest CO concentration, or V /V  = 1.0.  With
                                                   J.  o
this assumption, the highest observed persistence factor during the year

of data shown in Table A 6 is 0.603.  The model-predicted concentrations

using average 8-hour traffic volumes are multiplied by this empirical

factor to estimate maximum 8-hour CO concentrations.

                                   78

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Table A 13.  SUBTOTALS OF MODEL-PREDICTED CONTRIBUTIONS FROM 32
                  LINE SOURCES UNDER DIFFERENT ALTERNATIVES
Alternative
5-6 p.m. ,
5-6 p.m. ,
5-6 p.m. ,
8-9 p.m. ,
8-9 p.m. ,
8-9 p.m. ,
12-8 p.m. ,
12-8 p.m. ,
12-8 p.m. ,
3-11 p.m.
3-11 p.m.
3-11 p.m.
winds
winds
winds
winds
winds
winds
winds
winds
winds
, winds
, winds
, winds
200°
o
290
o
330
200°
o
290
330°
200°
rt
290°
330°
200°
O
290°
330°
Unadjusted
1
30.
28.
27.
14.
21.
20.
22.
18.
18.
18.
24.
22.
0
2
7
6
1
4
3
0
6
8
2
3.
CO concentration
2 3
27.8
36.2
22.4
18.1
31.2
17.3
16.6
34.2
14.9
22.2
28.6
20.4
24
14
13
22
10
6
18
10
8
22
10
9
.8
.8
.9
.1
.0
.3
.8
.4
.0
.9
.4
.9
at receptor
4 5
4.4
29.7
22.3
5.3
34.9
23.6
2.8
29.2
20.8
4.9
29.4
20.1
3.
10.
17.
3.
17.
17.
2.
10.
16.
3.
14.
14.
site
1
6
6
9
6
7
8
4
1
4
2
2
, ppm
6
neg.
56.1
24.1
neg.
23.4
22.5
neg.
31.2
23.0
neg.
31.3
22.7
                          79

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     14.  Estimate background concentrations.  Background values for the



proposed site can be obtained from the limited sampling data at the site



plus additional data from a non source oriented CO sampling station,



using approach number 3, page 52.  The estimated maximum background



values are:


                         (2.5) (4.4)       „ n
                    .  -            =  3.8ppm
          8-hour xb =      '2.1'      =  2'1 Ppm



     15.  Summarize predicted CO concentrations and compare to NAAQS.



After the adjusted 8-hour concentrations have been calculated using the



persistence factor and appropriate background concentrations have been



added, the resulting values can be compared to the NAAQS.  The data



shown in Table A 14 indicate that the 1-hour air quality standard of



35.0 ppm would be exceeded under certain conditions at three of the



receptor sites, generally as a result of emissions from nearby queuing



traffic lines.  However, violation of the 8-hour standard would be more



widespread, with concentrations above 9.0 ppm occurring at all six



receptor sites, during both 8-hour time periods evaluated, and with



prevailing winds from any of three directions.
                                  80

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Table A 14.  PREDICTED MAXIMUM 1- AND 8-HOUR CO
              CONCENTRATIONS AT PROPOSED SITE
Alternative
1-hour
5-6 p.m. ,
5-6 p.m. ,
5-6 p.m. ,
8-9 p.m. ,
8-9 p.m. ,
8-9 p.m. ,
8 -hour
12-8 p.m.,
12-8 p.m.,
12-8 p.m. ,
3-11 p.m.
3-11 p.m.
3-11 p.m.

winds
winds
winds
winds
winds
winds

winds
winds
winds
, winds
, winds
, winds

200°
290°
330°
200°
Q
290
o
330

200°
290°
330°
200°
290°
330°
CO
1

33
32
31
18
24
24

15
13
13
13
16
15

.8
.0
.5
.4
.9
.2

.5
.1
.3
.4
.7
.5
concentration at
2 3

31.
40.
26.
21.
35.
21.

12.
22.
11.
15.
19.
14.

6
0
2
9
0
1

1
7
1
5
3
4

28.6
18.6
17.7
25.9
13.8
10.1

13.5
8.4
6.9
15.9
8.4
8.1
receptor
4

8.
33.
26.
9.
38.
27.

3.
19.
14.
5.
19.
14.

2
5
1
1
7
4

8
7
6
1
8
2
site,
5

6.9
14.4
.21.4
7.7
21.4
21.5

3.8
8.4
11.8
4.2
10.7
10.7
ppm
6

3.8
59.9
27.9
3.8
27.2
26.3

2.1
20.9
16.0
2.1
21.0
15.8
                  81

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
  EPA 450/3-75-072
                              2.
                                                           3. RECIPIENT'S ACCESSION- NO.
4. TITLE AND SUBTITLE
                                                           5. REPORT DATE
 Application of the HIWAY
 Analysis:   User's Manual
Model for  Indirect Source
                                6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO.
  Kenneth  Axetell, Jr.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
  Kenneth  Axetel1 ,  Jr.
  Engineering  Consultant
  808  South Fairfax
  Alexandria,  Virginia   22314
                                                           10. PROGRAM ELEMENT NO.
                                11. CONTRACT/GRANT NO.


                                  5-02-3670A
 12. SPONSORING AGENCY NAME AND ADDRESS
  U.  S.  Environmental Protection  Agency
  Office of Air Quality Planning  and Standards
  Research  Triangle Park, N.  C. 27711
                                13. TYPE OF REPORT AND PERIOD COVERED
                                  Final
                                14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT

 A procedure for characterizing emissions of carbon monoxide occurring within
 parking lots as line sources  of pollution is described.   A line source dispersion
 model  (HIWAY) is then used  to illustrate an approach  for estimating the maximum
 impact of emissions from  vehicles in parking lots on  nearby 1- and 8- hour  ambient
 concentrations of carbon  monoxide.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                   b.lDENTIFIERS/OPEN ENDED TERMS  C. COS AT I Field/Group
  Air Pollution
  Airborne Wastes
  Atmospheric Contamination Control
  Vehicular Traffic
  Atmospheric Models
  Carbon Monoxide
                    HIWAY  Model
                    Parking Lots
                    Indirect Sources
13/02
13. DISTRIBUTION STATEMENT
  Unlimited
                                              19. SECURITY CLASS (ThisReport)
                                                Unclassified
                                              21. NO. OF PAGES
                                                  85
                                              20. SECURITY CLASS (This page)
                                                Unclassified
                                                                         22. PRICE
EPA Form 2220-1 (9-73)

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