vvEPA

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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing) 	
1. REPORT NO. 2
EPA 550/9-78-309
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Potential Effectiveness of Barriers Toward Reducing Highway
Noise Exposure on a National Scale
5.	REPORT DATE
July 1978
6.	PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Kenneth J. Plotkin, Vijay K. Kohli
8. PERFORMING ORGANIZATION REPORT NU.
WR 78-9
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Wyle Laboratories/Wyle Research
2361 Jefferson Davis Highway, ^404
Arlington, Virginia 22202
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-01-4374
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Noise Abatement and Control
2361 Jefferson Davis Highway
Arlington, Virginia 22202
13.	TYPE OF REPORT AND PERIOD COVERtU
Final —
14.	SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES

145. ABSTRACT 	
Calculations have been performed to assess the potential effectiveness of barriers toward
reducing noise exposure from the federal-aid highway system. Noise exposure, in terms of the
numbers of people exposed to greater than 60, 65, 70, and 75 dB, from the primary federal-
aid system was computed for present traffic flow and projected traffic through the year 2000.
Reductions in noise exposure were computed for several scenarios of constructing barriers along
urban interstate highways. It was found that significant reduction of noise exposure would require
barriers along most of the urban interstate system. The benefit (in terms of reduction of exposed
population) per mile of barrier construction was found to be greatest at high noise levels
(L^p > 75 dB). It was concluded that barriers would not provide a feasible method for abating
noise on a national scale. Their main benefit is to provide relief in extremely noisy local
applications.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b. IDENTIFIE RS/OPEN ENDED TERMS
c. COSATI Field/Group
Highway noise
Environmental noise
Noise Barriers


18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
- 24 _
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)

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550/9-78-309
POTENTIAL EFFECTIVENESS OF BARRIERS
TOWARD REDUCING HIGHWAY NOISE EXPOSURE
ON A NATIONAL SCALE
JULY 1978
CONTRACT NO. 68-01-4374
U.S. Environmental Protection Agency
Office of Noise Abatement and Control
Arlington, Virginia 22202
This report has been approved for general availability. The contents
of this report reflect the views of the contractor, who is responsible for
the facts and the accuracy of the data presented herein, and do not
necessarily reflect the official views or policy of EPA. This report does
not constitute a standard, specification, or regulation.

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Data
ROUTING AND TRANSMITTAL SUP
TO: (Name, office symbol, room number,
building, Agency/Post)
1.
Initials
Date

Action

File

Note and Return

Approval

For Clearance

Per Conversation

As Requested

For Correction

Prepare Reply

Circulate

For Your Information

See Me

Comment

Investigate

Signature

Coordination

Justify


REMARKS
Regional Representatives (3 copies)
EIS Coordinators	(3 copies)
•'
i
DO NOT un this form as a RECORD of approvals, concurr*nc««^tJi*poaa»<
clearances, and similar actions
FROM: (Name, org. symbol, Agency/Post)
Room No.—Bldg.
Phone No.
80*1-102 OPTIONAL Fl
SU.S. G.P.O. 1 977-241 -530/3090 FP««U«CffoC
3RM 41 (Rev. 7-76)
ISA
101-11.206

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* JpL \	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
i wzj
WASHINGTON DC 20460
OFFICE OF NOISE ABATEMENT
AND CONTROL
DATE:
NOV 31978
SUBJECT: EPA publication "Potential Effectiveness of
Barriers Toward Reducing Highway Noise Exposure
on A National Scale, July 1978" .j
FROM: John C. Schettino, .Clr^rtar
Technology and FederawProgrjama Divilsipn
u\ (1 ' U vj
TO:	Distribution List	Vi
As part of our effort to support ONAC'stask of developing a sub-strategy
for highway noise reduction, we have developed the attached publication.
It demonstrates that placement of barriers at noise sensitive locations -
the essence of FHWA's current noise policy - cannot be relied upon as
a general palliative for abating highway noise on a national scale. Bar-
riers can be beneficial in providing relief in extremely noisy local appli-
cations.
If you desire further copies of the report, please contact Mary Jane Bollman
(557-8292).
Distribution List
All ONAC and NED professional staff (1 copy each)
EPA Regional Representatives (3 copies each)
EPA Regional E1S Coordinators (3 copies each)
P. Cook, EPA/OFA (3 copies)

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TABLE OF CONTENTS
Page
1.0 INTRODUCTION		1
2.0 TRAFFIC ON FEDERALLY FUNDED HIGHWAYS		2
3.0 NOISE EXPOSURE FROM FEDERAL-AID HIGHWAYS		7
4.0 BARRIERS ON URBAN INTERSTATE HIGHWAYS		12
5.0 CONCLUSIONS		19
c.	LIST OF FIGURES
Fig.
No.
1	Numbers of People Exposed to Noise From Urban Interstates, 1974-2000. . 11
2	Changes in Noise Exposure From Urban Interstates in 1974 for Four
Barrier Scenarios	 18
LIST OF TABLES
Table
No.
1	Traffic on Federal-Aid Highways in 1974	 3
2	Road and Traffic Parameters	 4
3	Projected Traffic on Federal-Aid Highways in 2000 	 6
4	Vehicle Noise Levels (Energy-Average Maximum Pass-By Levels at
50 Feet (15 Meters))	 8
5	Area and People (Millions) Exposed to Noise Greater than Various Ljn
Values From Federally Funded Highways in 1974	 9
6	Area and People (Millions) Exposed to Noise Greater than Various Ljp
Values From Federally Funded Highways in 2000	 10
7	Distribution of Areas Exposed to Noise From Urban Interstates in 1974
For Several Barrier Heights	 13
8	Distribution of Areas Exposed to Noise From Urban Interstates in 2000
For Several Barrier Heights	 14
9	Noise Exposure From Urban Interstates in 1974 For Several Barrier Scenarios. . 16
10 Noise Exposure From Urban Interstates in 2000 For Several Barrier Scenarios. . 17
•
i

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Metric Conversions
All of the source data used in this study, obtained from federal government
agencies, were available only in English units. To permit this study to be directly keyed
to these source data, calculations were performed in English units. Final results have
been converted to metric, and are presented in both metric and English units. The
following conversion factors may be used to convert source data and intermediate cal-
culations from English to metric units:
1 foot
1 mile
1 square mile
0.305 meters (m)
1.609 kilometers (km)
2.589 square km
ii

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1.0 INTRODUCTION
Highway noise can be controlled by reducing vehicle noise levels, by altering
highway use anc(/or design, or by providing protection to exposed areas. These three
methods are listed above in decreasing order of generality, i.e., reduced vehicle levels
provide a nationwide benefit, modifying highway design or use benefits a particular
highway element or corridor, while protection to exposed areas benefits only specific
receivers. Potential nationwide benefits from vehicle noise reductions have been eval-
uated in a number of studies, for example Reference 1. These studies provide supporting
information for national vehicle noise standards which are the responsibility of the
2
United States Environmental Protection Agency.
Part of the responsibility for abating highway noise lies with the Federal Highway
3
Administration (FHWA) through its noise policy for federally funded projects. Federal-
aid systems consist of over 850,000 miles (1,370,000 kilometers), 22 percent of the
nation's total highway mileage, and handle approximately three-quarters of all highway
4
travel in the country. Although a variety of abatement measures are available, the
majority of highway noise abatement effected by FHWA has been achieved with barriers.
5
Barrier design procedures have been widely circulated by FHWA, and federal funding
is available for approved projects. Barriers are currently being constructed near noise-
sensitive areas along federally funded highway projects.
The intent of a barrier is to provide noise abatement in a particular area which
would otherwise receive excessively high noise levels. Barriers are thus inherently
local solutions, and are the primary noise control method used by FHWA. The pur-
pose of the present study is to examine barriers to determine whether they can provide
a feasible method for abating traffic noise on a national scale. This study estimates the
number of people exposed to noise from federal-aid highways from 1974 through 2000,
and the reduction of this exposure for several alternatives of barrier construction on a
national scale in 1974 and 2000. Calculations are limited to federal-aid highways
because these are the ones for which funding is generally available.
1

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2.0 TRAFFIC ON FEDERALLY FUNDED HIGHWAYS
The federal-aid highway system consists of the following three systems of roads^
•	Primary System — Rural routes and their urban extensions which are classified
as arterials. This includes the Interstate System.
•	Secondary System — Rural routes which are classified as major collectors
such as farm-to-market roads.
•	Urban System — All arterial and collector routes in urban areas (places of
5,000 or more population) which are not in the primary systems.
The highest traffic densities, hence the greatest potential for noise problems, are asso-
ciated with the primary system. The present study therefore considers only the primary
system.
Because of the difference in character between interstate and non-interstate
highways, and the population density difference between rural and urban areas, the
primary system has been divided into four parts for the purposes of this study:
•	Urban interstate
•	Urban primary, excluding interstate
•	Rural interstate
•	Rural primary, excluding interstate
Table 1 shows the traffic volume in 1974, in terms of average daily traffic (APT). Data
for ADT up to 40,000 are from Reference 7; distributions above this value are extrapolated
within the constraint that total road and vehicle mileage are consistent with values given
in Reference 7. Table 2 gives roadway configuration, speed, and the percentage of
medium- and heavy-duty trucks for each type of road. Truck percentages are from Ref-
erence 8; other data in Table 2 are assumed values typical of each type of road. Speeds
in Table 2 are consistent with data in Reference 9.
Traffic volumes on these four systems have been predicted for future years through
2000. The projections are based on a growth factor for total traffic volume and a growth
factor for road mileage for each system. The tabulated distributions shown in Table 1
2

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Table 1
Traffic on Federal-Aid Highways in 1974
Average Daily
Traffic (ADT)
(Thousands)
Miles of Road
Urban
Interstate
Urban
Primary*
Rural
Interstate
Rural
Primary*
0.4
38
242
83
8,610
0.4-1
2
223
448
32,259
1-2
23
858
1,756
50,386
2-3
31
1,267
2,511
33,911
3-4
82
1,573
2,788
21,064
4-5
137
1,520
3,075
12,895
5-10
902
7,556
11,077
21,115
10-15
1,076
5,391
6,364
4,373
15-20
1,093
3,424
2,834
1,318
20-30
1,742
3,253
2,059
705
30-40
1,129
1,109
472
122
40-60
o
o
*
660
204
48
60-80
840
450
—
—
80-100
600
335
¦¦¦
—
100-120
125
—

—
120-150
70
—
—
—
Total
Mileage
8,990
27,861
33,671
186,806
* Excluding Interstate
3

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Table 2
Road and Traffic Parameters

Urban
Urban
Rural
Rural

Interstate
Primary
Interstate
Primary
Speed (mph/kph)
55/88.5
35/56.3
55/88.5
55/88.5
g
Percent Trucks
8.7
3.4
15.6
8.2
Number of Lanes
8
4
3
2
Median Width
0
0
50/15
0
(feet/meters)*




* Median strip widths estimated here are the minimum which would
normally be found on each type highway.
4

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are first increased according to road mileage growth, then shifted upward so as to satisfy
the traffic volume growth. Growth factors used are based on the following:
•	Total traffic (vehicle miles) increases at a rate of 2.3 percent per year.
This is a composite value between estimated annual growths of 2.4 percent
for trucks^ and 2.0 percent for automobiles.^' The composite value is a
weighted average based on the relative contributions of these two vehicle
12
types to highway noise.
•	Volume (ADT) on rural interstates increases at a rate of 3.8 percent per year,
while road mileage remains approximately fixed. This is based on data in
Table 1-1 of Reference 10.
•	Total volume and road mileage of rural primaries increase at approximately
0.5 percent per year. This is based on the "full needs" case in Table 1-1
of Reference 10.
•	Mileage of urban primary roads is assumed to increase at a rate of 1 percent
per year, the rate of growth of the population. This is consistent with the
growth projections in Reference 13.
•	Urban interstate mileage is fixed at approximately 9,000 miles (14,480 km).
•	Traffic mix remains the same as given in Table 2.
Table 3 shows the projected traffic for the year 2000.
5

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Table 3
Projected Traffic on Federal-Aid Highways in 2000
Average Daily
Traffic (ADT)
(Thousands)
Miles of Road
Urban
Interstate
Urban
Primary*
Rural
Interstate
Rural
Primary*
<0.4
7
224
31
9,802
0.4-1
6
241
47
36,726
1-2
14
614
284
59,639
2-3
12
869
421
38,606
3-4
17
1,172
665
23,981
4-5
24
1,398
665
14,680
5-10
290
7,035
4,894
24,039
10-15
494
6,588
5,177
4,978
15-20
528
4,986
4,196
1,500
20-30
1,164
6,033
7,106
803
30-40
1,138
3,009
4,714
139
40-60
1,827
2,160
3,267
55
60-80
1,102
611
1,574
—
80-100
1,167
333
358

100-120
591
374
100
—
120-150
545
308
—
—
150-200
173
—
—

200-300
67

—
—
Total
Mileage
9,166
35,955
33,499
214,948
* Excluding Interstate
6

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3.0 NOISE EXPOSURE FROM FEDERAL-AID HIGHWAYS
The noise exposure to noise levels above Ly = 60, 65, 70, and 75 dB from the
federal-aid primary system has been computed* The computation was performed on the
following basis:
•	Distances to L. = 60, 65, 70, and 75 dB contours were computed for each
an
ADT range using the method of Reference 14. This model includes lane-by-
lane detail which is important for barrier calculation.
•	Vehicle noise levels used are given in Table 4, and are based on roadside
noise data in Reference 15 for automobiles, and Reference 16 for trucks.
•	The distance to each contour, less an assumed 50-foot (15-meter) setback
distance, was multiplied by the number of miles of road carrying each ADT,
then by 2, to obtain area exposed on both sides of the road. It is assumed
that noise exposure at a given point is from one road only.
•	The number of people exposed was then obtained by multiplying the area
by 4,500 people per square mile (1,737 per square km) in urban areas (this
is the median value of density in Table A-1 of Reference 18) and 56 people
per square mile (22 per square km) in rural areas (total U.S. population
divided by total U.S. area).
Table 5 summarizes the calculated exposure for 1974** for the four road types.
Table 6 shows the exposure in 2000 for the four systems. Figure 1 shows exposure
to Lyn £ 60, 65, 70, and 75 dB as a function of time for the urban interstate system.
* Previous EPA studies have identified levels above Ljn = 55 dB as significant when
considering public health and welfare.^ Calculations in the present study are pre-
sented only for 2 60 dB because highway barriers are usually practical for
alleviating only higher noise levels.
** The most recent year for which traffic and highway statistics were available at the
time of this calculation.
7

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Table 4
Vehicle Noise Levels
(Energy-Average Maximum Pass-By Levels
at 50 Feet (15 meters) )

Energy-Average Maximum Pass-By Level

at 50 Feet (15 meters)
Vehicle Type
35 mph (56.3 kph)
55 mph (88.5 kph)
Automobiles^
65.1 dB
71.4 dB
Trucks^
83.6 dB
87.5 dB
8

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Table 5
Area* and People** (Millions) Exposed to Noise
Greater Than Various Values From
Federally Funded Highways in 1974

Exceeded

60 dB
65 dB
70 dB
75 dB
Road System
Area
People
Area
People
Area
People
Area
People
Urban Interstate
(8,990 miles)
3,033
(7,852)
13.6
1,216
(3,148)
5.5
337
(872)
1.5
79
(205)
0.36
Urban Primary***
(27,861 miles)
1,590
(4,117)
7.2
431
(1,116)
1.94
54
(140)
0.24
1
(2.6)
0.005
Rural Interstate
(33,671 miles)
5,130
(13,282)
0.29
2,238
(5,794)
0.13
565
(1,463)
0.032
51
(132)
0.003
Rural Primary***
(186,806 miles)
8,871
(22,964)
0.50
2,255
(5,838)
0.13
364
(942)
0.020
14
(36)
0.001
* Square miles (square kilometers).
** People impacted based on 4,500 people/mi^ (1,738 per km^) in urban areas, and
56 people/mi^ (22 per km^) in rural areas.
*** Excluding interstate.
9

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Table 6
Area* and People** (Millions) Exposed to Noise
Greater Than Various Values From
Federally Funded Highways in 2000

Ljp Exceeded

60 dB
65 dB
70 dB
75 dB
Road System
Area
People
Area
People
Area
People
Area
People
Urban Interstate
(9,166 miles)
4,682
(12,122)
21.1
1,964
(5,085)
8.8
696
(1,802)
3.1
197
(510)
0.87
Urban Primary***
(35,955 mi les)
2,814
(7,285)
12.7
809
(2,095)
3.6
136
(352)
0.61
12
(31)
0.05
Rural Interstate
(33,499 miles)
13,154
(34,056)
0.74
5,724
(14,819)
0.32
1,954
(5,059)
0.11
488
(1,263)
0.03
Rural Primary***
(214,948 miles)
10,174
(26,340)
0.57
2,487
(6,439)
0.14
418
0,082)
0.023
16
(41)
0.001
* Square miles (square kilometers).
** People impacted based on 4,500 people/mi2 (1,738 per km2) in urban areas, and
56 people/mi2 (22 per km2) in rural areas.
*** Excluding interstate.
10

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Q.
1990
2000
1970
1980
Year
Figure 1. Numbers of People Exposed to Noise from Urban Inters fates, 1974-2000.
11

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4.0 BARRIERS ON URBAN INTERSTATE HIGHWAYS
The noise abatement potential of barriers has been evaluated by calculating
reduced exposure for several scenarios. The calculations are limited to urban interstates.
Rural highways are not included because their total exposure is small compared to urban.
Urban primary roads are not included because barriers are rarely practical on them due
to cross-streets, need for access, etc.
Tables 7 and 8 show the distribution of noise exposure in 1974 and 2000 for no
barriers and for 10-foot (3-meter), 15-foot (4.5-meter), and 20-foot (6-meter) high
barriers* Barriers higher than 20 feet (6 meters) would give little or no additional benefit.
Shown for each ADT range are the distances to the = 60, 65, 70, and 75 dB contours
with no barriers, and the areas exposed for no barriers and for the 3 height barriers. The
barrier calculations were performed using the method of Reference 19, and include the
following assumptions:
•	Level terrain. Shielding by existing buildings is not accounted for.
•	All receivers are at first-story level, i.e., high-rise residences are not
accounted for.
•	Barriers are vertical walls parallel to the road, with sound transmission
through the wall negligible.
•	Barriers located 25 feet (7.5 meters) to each side of the road.
Four barrier-use scenarios have been considered, each with the goal of eliminating
(where feasible) exposure to Ldn above a given value. These are:
A.	Eliminate exposure above Ljn = 75 dB. This requires construction of 15-foot
(4.5-meter) barriers where ADT >100K, and 10-foot (3-meter) barriers where
30K< ADT < 100K.
B.	Eliminate exposure above = 70 dB. This requires 20-foot (6-meter) barriers
where ADT > 80K, 15-foot (4.5-meter) barriers where 30K < ADT < 80K, and
10-foot (3-meter) barriers where 10K < ADT < 30K.
* Only these three heights were considered in the calculations and in the ensuing discus-
sion. Equivalent reduction to exposure could be achieved in some cases with lower barriers,
e.g., 4.5-meter barriers are assumed here in places where barriers taller than 3 meters But
less than 4.5 meters would suffice.
12

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Table 7
Distribution of Areas Exposed to Noise From Urban Interstates in 1974
For Several Barrier Heights
Average
Daily
Traffic
(ADI)
Miles
of Road
Distance (Feet) From Center of
Outer Lane to Contour,
No Barrier
Exposed Area, Square Miles
No Barrier
10 ft (3m) Barrier
15 ft (4.5m) Barrier
20 ft (6m) Barrier
60
65
70
75
60
65
70
75
60
65
70
75
60
65
70
75
60
65
70
75
<400
38
	
—
—
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
400-1K
2
	
—
—
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1-2K
23
84
—
—
—
0.3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2-3 K
31
138
—
—
—
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3-4K
82
180
70
—
—
4
0.6
0
0
2.3
0
0
0
0
0
0
0
0
0
0
0
4-5K
137
219
80
—
—
8.8
1.6
0
0
5.1
0
0
0
0
0
0
0
0
0
0
0
5-1 OK
902
310
135
—
—
88
29
0
0
71.3
0
0
0
0
0
0
0
0
0
0
0
10-15K
1,076
450
195
72
—
163
59
8
0
150
28
0
0
14.6
0
0
0
0
0
0
0
15-20K
1,093
600
245
93
—
227
80
17
0
227
53
0
0
33
0
0
0
14
0
0
0
20-30K
1,742
800
325
125
50
494
181
49
0
494
141
0
0
92
3
0
0
92
0
0
0
30-40K
1,129
1,050
430
172
68
427
162
52
7
427
148
18
0
94
12
0
0
67
0
0
0
40-60K
1,100
1,350
590
230
94
541
225
75
18
541
223
41
0
137
32
0
0
108
13
0
0
60-80K
840
1,650
740
300
120
509
219
79
22
509
219
62
0
141
38
0
0
120
21
0
0
80-100K
600
1,800
880
350
150
397
188
68
22
397
188
54
0
113
37
1.8
0
99
24
0
0
100-120K
125
2,300
1,000
420
185
106
44
17
6
106
44
15
2.5
32
9
1.3
0
27
5
0
0
120-150K
70
2,600
1,100
520
220
67
27
12
4
12
27
26
10
20
6
1.5
0
18
4.7
0.4
0

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Table 8
Distribution of Areas Exposed to Noise From Urban Interstates in 2000
For Several Barrier Heights
Average
Daily
Traffic
(ADT)
Miles
of Road
Distance (Feet) From Center of
Outer Lane to Ljp Contour,
No Barrier





Exposed Area,
Square Miles







No Barrier
10 ft (3m) Barrier
15 ft (4.5m) Barrier
20 ft (6m) Barrier
60
65
70
75
60
65
70
75
60
65
70
75
60
65
70
75
60
65
70
75
<400
7
—
—
—
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
400-1K
6
—
—
—
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1-2K
14
84
—
—
—
0.2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2-3K
12
138
—
—
—
0.4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3-4K
17
180
70
—
—
0.8
0.1
0
0
0.5
0
0
0
0
0
0
0
0
0
0
0
4-5 K
24
219
80
—
—
1.5
0.3
0
0
0.9
0
0
0
0
0
0
0
0
0
0
0
5-iOK
290
310
135
—
—
28.5
9.3
0
0
23
0
0
0
0
0
0
0
0
0
0
0
10-I5K
494
450
195
72
—
74
27
4.1
0
69
12.9
0
0
6.7
0
0
0
0
0
0
0
15-20K
528
600
245
93
—
110
39
8.6
0
110
25.7
0
0
16
0
0
0
6.8
0
0
0
20-30K
1,164
800
325
125
50
330
121
33
0
330
94
0
0
61
2.5
0
0
61
0
0
0
30-40K
1,138
1,050
430
172
68
431
163
52
7
431
150
18
0
94
12
0
0
68
0
0
0
40-60K
1,827
1,350
590
230
94
899
373
124
30
899
370
68
0
227
53
0
0
179
22
0
0
60-80K
1,102
1,650
740
300
120
667
287
104
29
667
287
82
0
184
49
0
0
157
14
0
0
80-100K
1,167
1,800
880
350
150
773
336
132
44
773
366
106
0
220
73
3.5
0
193
46
0
0
100-120K
591
2,300
1,000
420
185
503
212
82
30
503
212
70
11
151
42
6.3
0
127
23
0
0
120-150K
545
2,600
1,100
520
220
526
216
V
35
526
216
21
20
157
48
11.4
0
145
36
2.9
0
150-200K
173
3,500
1,600
660
280
226
101
39
15
226
101
39
11
65
62
6.6
0
65
22
3.6
0
200-300K
67
4,500
2,000
840
360
112
49
20
7
112
49
20
6
29
26
3.9
0
29
13
3.4
0

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C.	Eliminate exposure above = 65 dB. This requires 20-foot (6-meter)
barriers where ADT >20K, 15-foot (4.5-meter) barriers where 10K < ADT < 20K,
and 10-foot (3-meter) barriers where 3K < ADT < 10K.
D.	Eliminate exposure above = 60 dB. This requires 20-foot (6-meter) barriers
where ADT > 10K, 15-foot (4.5-meter) barriers where 3K< ADT < 10K, and
10-foot (3-meter) barriers where 1K < ADT < 3K.
Tables 9 and 10 show the distance required of each height barrier (in miles and
kilometers), and the exposure for each scenario, in 1974 and 2000. Note that the goal
of each scenario is not necessarily achieved because of the limit of effectiveness of barriers
limited to a practical height of no more than 20 feet (6 meters).
Figure 2 shows the 1974 exposure data from Table 9 in graphical form. The first
application of barriers (Scenario A) has its greatest effect at high noise levels. The
other scenarios, with more extensive barriers, tend to shift the distribution downward,
with a residual tail at high levels which cannot be eliminated with barriers.
Because barriers provide larger noise reduction at close locations where noise
levels are highest, the benefit of barrier application is first seen at higher noise levels,
but the benefit at high levels does not increase with greater application of barriers. All
four scenarios have the same reduction to population exposure above = 75 dB. A
more modest scenario of eliminating half the exposure above 75 dB in 1974 (half the goal
of Scenario A) would require 2,163 miles (3,476 kilometers) of barrier, about one-quarter
that required for Scenario A.
15

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Table 9
Noise Exposure From Urban Interstates in 1974
For Several Barrier Scenarios
Scenario
Miles (Kilometers) of
Barriers
People Exposed to Greater Ldn
(Millions)
10 ft (3m)
15ft(Wwd
20 ft (6m)
60dB
65 dB
70 dB
75 dB
Baseline — No Barrier
0
0
0
13.6
5.5
1.5
0.36
A — Eliminate Exposure Above
Ldn = 75 dB
7,338
(11,792)
390
(627)
0
13.1
5.1
1.1
0
B — Eliminate Exposure Above
Ldn = 70 dB
7,822
(12,570)
6,138
(9,864)
1,590
(2,555)
6.7
1.7
0.002*
0
C — Eliminate Exposure Above
Ldn = 65 dB
2,242
(3,603)
4,338
(6,971)
11,212
(18,018)
3.0
0.31*
0.002
0
D — Eliminate Exposure Above
= 60 dB
108
(174)
2,242
(3,603)
15,550
(24,989)
2.5*
0.31
0.002
0
* Not feasible to eliminate completely exposure with barriers.
16

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Table 10
Noise Exposure From Urban Infers fates in 2000
For Several Barrier Scenarios
Scenario
Miles
(Kilometers) of
Barriers
People
Exposed to Greater Ldn
(Millions)

10 ft (3m)
15ft(4.5m)
20 ft (6m)
60 dB
65 dB
70 dB
75 dB
Baseline — No Barriers
0
0
0
21.1
8.8
3.1
0.87
A — Eliminate Exposure Above
Ldn = 75 dB
10,468
(15,822)
2,752
(4,422)
0
16.7
7.0
1.6
0
B — Eliminate Exposure Above
Ldn = 70 dB
4,372
(7,026)
8,134
03,071)
5,086
(8,173)
7.2
1.8
0.045*
0
C — Eliminate Exposure Above
Ldn = 65 dB
662
(1,064)
2,044
(3,285)
15,548
(24,986)
4.8
0.79*
0.045
0
D — Eliminate Exposure Above
Ldn = 60 dB
52
(84)
662
(1,064)
17,592
(28,270)
4.6*
0.79
0.045
0
* Not feasible to eliminate completely exposure with barriers.
17

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SCENARIO (See Table 9)
Baseline
A
Ldn' dB
Figure 2. Changes in Noise Exposure From Urban Interstates in 1974 for
Four Barrier Scenarios.
18

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5.0 CONCLUSIONS
Calculations have been performed of the numbers of people exposed to noise
from the federal-aid highway system. It was found that the majority of exposure to
high noise levels (L , > 75 dB) is due to traffic on urban interstates.
an
The potential effectiveness of barrier construction toward reducing noise
exposure from federal-aid highways was evaluated by considering wide-scale construc-
tion of barriers along urban interstate highways. Four scenarios considered were con-
structing barriers to eliminate exposure above = 60, 65, 70, and 75 dB. It was
found that these four scenarios would require extraordinarily large mileages of barriers —
both sides of more than half of the urban interstates.
The present calculation is not sufficiently detailed to permit calculation of
scenarios involving exposure only to levels higher than those noted above. However,
a trend was seen that the benefits (in terms of reduction of exposed population) per mile
of barrier are greatest when applied to relieve extremely high noise levels. This has
been the intended purpose of barriers in virtually all applications. General reduction
of highway noise at moderate levels would require clearly impractical magnitudes of
construction.
It is therefore concluded that barriers constructed along federal-aid highways
would not provide a feasible method for abating traffic noise on a national scale.
Their main benefit is to provide relief in extremely noisy local applications.
19

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REFERENCES
1.	"Background Document for Medium and Heavy Truck Noise Emission Regulations",
EPA-550/9-76-008, March 1976.
2.	Noise Control Act of 1972, Public Law 92-574, 92nd Congress, HR 11021,
October 27, 1972.
3.	Federal-Aid Highway Program Manual (FHPM), Volume 7, Chapter 7. Federal
Highway Administration, May 1976.
4.	"A Statement of National Highway Transportation Policy", Federal Highway
Administration, December 1976.
5.	Simpson, M.A., "Noise Barrier Design Handbook", FHWA Report No. RD-76-58,
1976.
6.	"America on the Move!", U.S. Federal Highway Administration, 1977.
7.	"Highway Statistics 1974", Highway Statistics Division, Office of Highway
Planning, Federal Highway Administration.
8.	Kent, P., and Bishop, H., "1974 National Truck Characteristics Report",
Planning Services Branch, Office of Highway Planning, Federal Highway
Administration, April 1974.
9.	"The Status of the Nation's Highways: Conditions and PerformanceReport of
the Secretary of Transportation to the United States Congress, September 1977.
10.	"Interagency Study of Post-1980 Goals for Commercial Motor Vehicles", draft,
June 1976.
11.	"The Report by the Federal Task Force on Motor Vehicle Goals Beyond 1980",
draft, September 2, 1976.
12.	Plotkin, K.J., and Sharp, B.H., "Assessment of Highway Vehicle Noise Control
Strategies", InterNoise 74, October 1974.
13.	"Area Economic Projections 1990", U.S. Department of Commerce, 1976.
14.	Plotkin, K.J., "A Model for the Prediction of Highway Noise and Assessment
of Strategies for its Abatement Through Vehicle Noise Control", Wyle Research
Report WR 74-5, prepared for the U.S. Environmental Protection Agency,
September 1974.
20

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REFERENCES (Cont'd)
15.	Olson, N., "Statistical Study of Traffic Noise", APS-476, National Research
Council of Canada, Division of Physics, 1970.
16.	Sharp, B.H., "A Survey of Truck Noise Levels and the Effect of Regulations",
Wyle Research Report WR 74-8, December 1974.
17.	"Information on Levels of Environmental Noise Requisite to Protect Public Health
and Welfare With an Adequate Margin of Safety", Report No. 550/9-74-004,
U.S. Environmental Protection Agency, March 1974.
18.	Rackl, R., Sutherland, L., and Swing, J., "Community Noise Countermeasures
Cost-Effectiveness Analysis", Wyle Research Report WCR 75-2, prepared for the
Motor Vehicle Manufacturers Association, July 1975.
19.	Sharp, B.H., Plotkin, K.J., Glenn, P.K., and Slone, R.M., "A Manual for
the Review of Highway Noise Impact", Wyle Research Report prepared for the
U.S. Environmental Protection Agency, No. EPA-550/9-77-356, May 1977.
^U.S. GOVERNMENT PRINTING OFFICE: 1 97 8-720-335/61 69-31
21

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