vvEPA ------- 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) ------- 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. ------- 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 ------- * 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) ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- Q. 1990 2000 1970 1980 Year Figure 1. Numbers of People Exposed to Noise from Urban Inters fates, 1974-2000. 11 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- SCENARIO (See Table 9) Baseline A Ldn' dB Figure 2. Changes in Noise Exposure From Urban Interstates in 1974 for Four Barrier Scenarios. 18 ------- 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 ------- 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 ------- 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 ------- |