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From page 1...
... 55.- A Decade of Experience P E _..__I IIi'l sPSPELIIVI'Ij LI . Ii 5 ;m M Im g 1ja Transportation Research Board Special Report 204 National Research Council Eli LIMI LUV1H LEQTt
From page 2...
... 1984 TRANSPORTATION RESEARCH BOARD EXECUTIVE COMMITTEE OFFICERS CHAIRMAN: Joseph M Clapp, Senior Vice President, Roadway Express, Inc., Akron, Ohio VIcE CHAIRMAN: John A
From page 3...
... 55: A Decade' of Experience Transportation Research Board Special Report 204 National Research Council Washington, D.C.
From page 4...
... Transportation Research Board Special Report 204 Price $14.00 Edited for TRB by Edythe Traylor Crump mode I highway transportation subject areas 17 energy and environment 51 transportation safety 54 operations and traffic control Transportation Research Board publications are available by ordering directly from TRB. They may also be obtained on a regular basis through organizational or individual affiliation with TRB; affiliates or library subscribers are eligible for substantial discounts.
From page 5...
... COMMITTEE FOR THE STUDY OF.THE BENEFITS AND COSTS OF THE 55 MPH NATIONAL MAXIMUM SPEED LIMIT ALAN A ALTSHULER, New York University, Chairman HARRY T
From page 6...
... Transportation Research Board Staff DAMIAN J KULASH, Assistant Director for Special Projects FRANCIS P
From page 7...
... Preface In 1982 Congress expressed concern that eroding compliance with the 55 mph national maximum speed limit threatened the safety of America's highways. Several states had weakened their penalties for violations of the 55 mph speed limit, and some members of Congress became concerned that this would encourage faster driving and impair highway safety.
From page 8...
... vi Preface estimates of the benefits and costs of the 55 mph speed limit, even though measurement of most effects is imprecise. In determining the effects on safety, analysis is confounded by the difficulty of isolating the effects of the speed limit from other causes of the improved safety record.
From page 9...
... Preface vii Altshuler, Dean of the Graduate School of Public Administration at New York University; his guidance and direction are greatly appreciated. The study was performed under the supervision of Dr.
From page 10...
... Contents EXECUTIVE SUMMARY ............................................
From page 11...
... 4 ESTIMATED REDUCTIONS IN INJURIES AND INJURY SEVERITY .........76 Injury Data Limitations, 77 Injury Rate Trends, 78 Economic Savings, 89 Summary, 90 References, 91 5 TAXPAYER COSTS AND BENEFITS .................................. 93 Taxpayer Benefits, 94 Public Costs, 100 Conclusion, 102 References, 103 6 ENERGY SAVINGS ................................................
From page 12...
... APPENDIX A: Effect of the Fuel Shortage on Recreational Travel in 1974 182 APPENDIX B: Effectiveness of Safety Belts in Reducing Highway Fatalities .....................................................187 APPENDIX C: Speeding and Highway Fatalities....................200 APPENDIX D: State Penalties For Violation of the 55 mph Speed Limit.........................................................209 APPENDIX E: Analysis of Speedometer Adjustments ..............218 APPENDIX F: Survey of State Traffic Enforcement Administrators 225 APPENDIX G: Estimates of Taxpayer Benefits .....................232 APPENDIX H: Further Research...................................240 APPENDIX I: Detailed Tables .....................................
From page 13...
... Executive Summary To assist the Congress in setting policy on the 55 mph national maximum speed limit, the conclusions of the Committee for the Study of Benefits and Costs of the 55 mph National Maximum Speed Limit are summarized as follows: Findings of the committee about the effect of the 55 mph speed limit on safety, energy, travel time, and taxpayer costs; Recommendations of the committee for continuation of the 55 mph speed limit and the mechanism by which state compliance is measured; and Unresolved Issues that surround the appropriate speed limit for selected roads. FINDINGS Enacted during the Arab oil embargo to conserve fuel, the 55 mph speed limit became effective in all states by March 1974.
From page 14...
... 55: A DECADE OF EXPERIENCE Consequences of the 55 mph Speed Limit in 1974 Not all of the 9,100 fewer fatalities that occurred on the nation's highways in 1974 can be attributed to the 55 mph speed limit, however. Part of the reduction in fatalities in 1974 can be attributed to economic conditions and fuel shortages that curtailed the amount of driving.
From page 15...
... Executive Summary 3 speed driven by motorists on rural Interstates has crept upward from 57.6 mph in 1974 to 59.1 mph in 1983, it is still far below the average of 65 mph that prevailed in 1973. More important, the distribution of highway speeds continues to be narrower than before the 55 mph speed limit became effective, and this reduced variance enhances highway safety.
From page 16...
... 4 55: A DECADE OF EXPERIENCE Taxpayer Costs Several government programs provide benefits that may be affected by highway fatalities, disabilities, and injuries. The chief programs are Medicare, Medicaid, and Old Age Survivors and Disability Insurance.
From page 17...
... Executive Summary insurance costs, and as a result, most large trucking firms support the 55 mph speed limit. Residents in rural areas of the United States drive more than the average American on highways posted at 55 mph, and the above average cost in additional travel time for residents of predominantly rural states may explain the somewhat lower level of support for the law outside of the Northeast.
From page 18...
... 6 55: A DECADE OF EXPERIENCE TABLE 1 Major Effects of the 55 mph Speed Limit Total Effect of Impact Area for 1983 Speed Limit Percentage Highway fatalities 44,300 (-)
From page 19...
... Executive Summary 7 withholding of federal highway funds from a state in which more than 50 percent of all motorists exceed the speed limit on the roads posted at 55 mph. Adjustments for speedometer error and sampling error that are permitted under current law make this requirement less stringent than it first appears, but the committee finds the rationale and magnitude of these adjustments to be arbitrary.
From page 20...
... 55: A DECADE OF EXPERIENCE reallocation appears desirable in many instances and would redress one of the charges now made against the 55 mph speed limit, namely, that it' encourages police agencies to misallocate resources on offenses that present relatively minor safety risks. UNRESOLVED ISSUES The committee was divided on the question of speed limits for rural Interstate routes.
From page 21...
... Executive Summary 9 that some states will be unable to demonstrate compliance, thereby subjecting themselves to a loss of some federal-aid highway funds. Decreasing compliance, along with slipping public support and an apparent lack of support in some state legislatures, could ultimately lead to the nullification of this law.
From page 22...
... 10 55: A DECADE OF EXPERIENCE Could Safety be Enhanced by Permitting Relaxation of the 55 mph Speed LimitIf Other Effective Safety Policies Are Enacted To Replace it? The committee recognized the immense practical difficulties of enacting a widespread behavioral change on the scale of the 55 mph speed limit, and it discussed whether the public determination could be mustered to introduce other laws of this significance.
From page 23...
... Executive Summary 11 Because Interstate routes have a better safety record than other road systems, relaxation of the speed limit on rural Interstate routes would probably not have a proportional impact on safety. If the speed limit were increased to 60 or 65 mph on all 31,500 miles of rural Interstate routes, about 19 percent of all traffic on roads posted at 55 mph would be affected.
From page 24...
... 12 55: A DECADE OF EXPERIENCE produce system-wide changes in driving behavior. The strength of the spillover effect cannot be firmly established but it does provide one more reason for caution in contemplating upward adjustments in the 55 mph speed limit.
From page 25...
... Executive Summary 13 than the medium- and high-penalty states. But some of the individual states within the low-penalty group had lower speeds and lower fatality rates than many of the states in the other two categories.
From page 26...
... 14 55: A DECADE OF EXPERIENeE Is Control of Speed Limits a State or a Federal Responsibility? Aside from temporary federal action during World War II, speed limit policy had always been a responsibility of state and local governments before 1974.
From page 27...
... 1 Introduction For the past decade -- since March 1974 -- a maximum speed limit of 55 mph has been in effect on the iiation's highways. Originally enacted as a temporary fuel conservation measure, Congress made the 55 mph speed limit permanent because of the apparent safety benefits.
From page 28...
... 16 55: A DECADE OF EXPERIENCE of 1982, proponents of the 55 mph speed limit proposed sanctions against those states whose penalties for speeding did not embody a substantial deterrent to violators. A compromise reached in the House and Senate conference requested that the National Research Council investigate the benefits of the law and determine whether the states with reduced penalties experienced more speeding.1 In response to this legislative mandate, a careful assessment is made in this study of the impact of the 55 mph speed limit on lives, injuries, travel time, fuel conservation, and taxpayer costs, Individual state laws and enforcement policies are examined to determine whether they affect motorist compliance with the 55 mph speed limit.
From page 29...
... Introduction 17 SCOPE OF THE STUDY The chapters that follow focus on how the 55 mph speed limit affects driving behavior and how that behavior, in turn, affects the national welfare. In Chapter 2 the changes in driving behavior brought about by the enactment of the 55 mph speed limit are described.
From page 30...
... 18 55: A DECADE OF EXPERIENCE the relationship between speed limits and motorist behavior. Areas where further research is needed are noted in Appendix H
From page 31...
... 2 The Reductions in Speeds Resulting From the 55 MPH Speed Limit As early as November 1973 a number of states began lowering posted speed limits as part of the national effort to reduce fuel consumption. By March 1974 all states had reduced maximum speed limits to 55 mph.
From page 32...
... 20 55: A DECADE OF EXPERIENCE are examined in this chapter, following an overview of the different types of highways affected by the 55 mph speed limit. THE HIGHWAY SYSTEM: MILEAGE, TRAVEL, AND SAFETY Each year Americans drive more than a trillion miles on nearly 4 million miles of streets and highways.
From page 33...
... INTERSTATES - - AND FREEWAYS 26% 12%F1 Mileage Travel Fatalities ARTERIALS °/ 1. K - 48 iWI 9% Mileage Travel Fatalities -, COLLECFORS 21% 17' 237o Mileage Travel Fatalities LOCALS 69% 14 % 107 % Mileage Travel Fatalities FIGURE 1 Roads and highways: mileage, travel, and safety (1-3)
From page 34...
... 22 55: A DECADE OF EXPERIENCE Collector highways collect rural and urban traffic and funnel it toward arterial highways. They make up 21 percent of total mileage and carry 18 percent of all travel.
From page 35...
... Interstates and Freeways (1%) Interstates and Freeways (less than Arterials :10/0)
From page 36...
... 24 55: A DECADE OF EXPERIENCE Interstate Highways The 55 mph speed limit caused a decrease in the average highway speeds on rural Interstates by dramatically curtailing the percentage of motorists driving at extremely high speeds. The percentage of drivers exceeding 65 mph on the rural Interstates declined from 50 to 9 percent during the first year the 55 mph speed limit was in effect.
From page 37...
... 50 1972 1974 1976 1978 1980 1982 65 55 Reductions in Speeds 25 FIGURE 5 Trend in average speeds on Interstate highways (5)
From page 38...
... 40 35 - 30 U 25 20 13 - f- z U 10 35 40 45 50 55 60 65 70 75 80 SPEED (mph) FIGURE 6 Trend in speed variability (standard deviation)
From page 39...
... 40 0 40 0 30 35 40 45 50 55 60 65 70 75 80 MILES PER HOUR 30 35 40 45 50 55 60 65 70 75 80 MILES PER HOUR FIGURE 7 Change in speed distribution on non-Interstate rural highways, 1973-1974 (4)
From page 40...
... 28 55: A DECADE OF EXPERIENCE the pronounced reductions in average speeds across all major highway systems. Completeness of Sample Before 1976 not all states reported speed data to the Federal Highway Administration (FHWA)
From page 41...
... Reductions in Speeds 29 average speeds, whereas those states that already had loop monitors recorded an average increase in speeds of only 0.8 percent. Loop monitors record higher average speeds than radar for two reasons.
From page 42...
... 30 55: A DECADE OF EXPERIENCE As public concern about fuel supplies waned, motorists began to drive faster. However, on rural Interstate highways average speeds remain well below pre-55 mph speed limit levels.
From page 43...
... 3 Highway Safety and the 55 MPH Speed Limit During the Arab oil embargo of late 1973 and early 1974, the industrialized nations of the West experienced their first major shortage of petroleum. Many nations responded by implementing energy conservation measures such as reduced speed limits.
From page 44...
... 55 50 1 45 40 35 30 25 20 . 15 FO 10 0 5 n NUMBER OF FATALITIES 1945 1950 1955 1960 1965 1970 1975 19801982 FATALITY RATE 1 0 1945 1950 1955 1960 1965 1970 1975 19801982 FIGURE 8 Fatalities and fatality rate on all roads dnd highways, 19461982 (1)
From page 45...
... Highway Safety and the 55 mph Speed Limit 33 rate trend since 1946. Thus, even had the energy crisis not occurred, and had speed limits not been lowered in 1974, some decline in the fatality rate would have been expected in 1974 because of the prevailing downward trend.
From page 46...
... 34 55: A DECADE OF EXPERIENCE cies, such as motor vehicle standards and drunk driving campaigns. The influence of economic and demographic factors on the number of highway fatalities is also discussed.
From page 47...
... 6 Highway Safety and the 55 mph Speed Limit 35 ALL ROADS HIGHWAYS S
From page 48...
... 36 55: A DECADE OF EXPERIENCE Reaction Time Modern highways are designed such that under optimal conditions a driver has at least 2.5 seconds after he perceives an accident situation well down the highway to decide to respond and to take corrective action (5)
From page 49...
... Highway Safety and the 55 mph Speed Limit 37 Curves Speed influences steering when negotiating curves on lower-quality highways. If a driver enters a curve lacking adequate superelevation at too high a speed, he may cut the curve, and thereby cross into the opposite lane.
From page 50...
... 38 55: A DECADE OF EXPERIENCE ers traveling at 65, 60, and 55 mph, the fastest driver, on approaching a truck overturned ahead, will travel much farther while reacting, needs much more distance to come to a stop, and will crash into the truck at a higher impact speed.2 Assuming a truck is blocking the road 290 ft ahead of these three drivers, the driver traveling at 65 mph will crash into the truck at 35 mph, would certainly be injured with such a great change in velocity, and could be killed. The driver traveling at 60 mph will crash into the truck at 22 mph and has a greater probability of surviving.
From page 51...
... Highway Safety and the 55 mph Speed Limit 39 possibility of fatality increases dramatically as the change in velocity during the collision increases (8)
From page 52...
... 100,000 E : 10,000 0 E 1,000 C 100 -30 -20 -10 0 +10 +20 +30 VARIATION FROM MEAN SPEED (mph) FIGURE 12 Accident involvement rate by variation from mean speed (10)
From page 53...
... Highway Safety and the 55 mph Speed Limit 41 NATIONWIDE EXPERIENCE WHEN THE 55 MPH SPEED LIMIT BECAME LAW IN 1974 Because speed is known to affect highway safety, based on assessment of the physical relationships involved as well as actual reported expe- rience with accidents, it was expected that enactment of the 55 mph national maximum speed limit in 1974 would cause a decline in highway fatalities and injuries. Nevertheless, the magnitude of the decline9,100 fewer fatalities in 1974 than in 1973 -- was so dramatic that renewed attention was given to the safety consequences of highway speeds.
From page 54...
... 42 55: A DECADE OF EXPERIENCE the speed limit, reduced travel, and a variety of other factors were identified (15)
From page 55...
... Highway Safety and the 55 mph Speed Limit 43 trends are too short to project the expected fatality rate for 1974 (independent of the 55 mph speed limit) with any great confidence.
From page 56...
... 44 55: A DECADE OF EXPERIENCE Three travel-related aspects of this context are particularly important in assessing the relative contribution of the 55 mph speed limit: The extent to which highway travel declined in, 1974, Whether accident-prone types of travel declined more than average, and Whether travel by accident-prone groups declined more than average. Declines in Total Travel Some decline in the absolute number of highway fatalities would have been expected in 1974 simply as a consequence of the reduction in travel.
From page 57...
... Highway Safety and the 55 mph Speed Limit 45 does not affect the conclusion that something unusual affected the pattern in 1974. Furthermore, reliable toll road receipts for 1974 provide a further check on travel estimates because travel data from toll receipts are also derived from actual vehicle counts.
From page 58...
... 46 55: A DECADE OF EXPERIENCE Declines in Discretionary Travel If individuals drove less on weekends, and at night, and took fewer vacation trips, fatalities would decrease because these types of trips involve above average fatal accident rates. National measures of such travel do not exist.
From page 59...
... Highway Safety and the 55 mph Speed Limit 47 TABLE 3 Visits to National Parks, 1971-1980 (000s)
From page 60...
... 48 55: A DECADE OF EXPERIENCE Males, another higher than average risk group, also maintained a constant share of total fatalities from 1971 to 1976 (20)
From page 61...
... Highway Safety and the 55 mph Speed Limit 49 all types of roads, not on just those posted above 55 mph. Two plausible hypotheses were offered: (a)
From page 62...
... 50 55: A DECADE OF EXPERIENCE scale, with a score of 7 being the most severe. Fatal accidents in Texas in which the vehicles involved were scored as a 6 or 7 declined 30 percent based on a comparison between the first 6 months of 1973 and the first 6 months of 1974 (32)
From page 63...
... TABLE 5 Estimated Effects of 55 mph Speed Limit in Individual States State Highway System Time Period of Study Methodology Estimated Effect of 55 mph Speed Limit Arizona (25) Interstate, U.S.
From page 64...
... TABLE 5 (continued) Time Period of Estimated Effect of 55 mph Speed State Highway System Study Methodology Limit Michigan (35)
From page 65...
... Highway Safety and the 55 mph Speed Limit 53 (37)
From page 66...
... TABLE 6 Experiments with Speed Limits Before Energy Crises of 1974 and 1979 Jurisdiction Speed Limit (mph) pre post Highway Type Years Effect on Safety Comment Finland (40)
From page 67...
... New Zealand 55 to 60 50 Rural roads (43) Ontario (44)
From page 68...
... 56 55: A DECADE OF EXPERIENCE level. It is also consistent with the studies of national data, which generally estimate that as a result of the 55 mph speed limit fatalities were reduced by 3,200 to 7,500 lives in 1974.
From page 69...
... Highway Safety and the 55 mph Speed Limit 57 Speeds in the 1973-1983 Decade Although speeds have increased during the last decade, speeds on main rural highways remain well below the levels of 1973. Average speeds on rural Interstates declined by 7.4 mph in 1974.
From page 70...
... 58 55: A DECADE OF EXPERIENCE nation's travel on high-speed roads remains well below the levels that prevailed before the 55 mph speed limit. Other Improvements to Roads, Vehicles, Medical Services, and Driver Behavior Some of the safety benefits that accompanied the introduction of the 55 mph speed limit in 1974 might not be lost if speed limits were increased today, because improvements during the last decade make high-speed driving less risky than it formerly was.
From page 71...
... Highway Safety and the 55 mph Speed Limit 59 Although no comprehensive evaluation of the benefits of improved emergency medical services has been made, reports from individual jurisdictions note substantial improvements in safety due to improved ambulance services (50,51)
From page 72...
... 60 55: A DECADE OF EXPERIENCE installed. Highways of Interstate design quality, which incorporate, many of these improvements, have safety records two to four times better than other roads.
From page 73...
... Highway Safety and the 55 mph Speed Limit 61 in the next section, however, the benefit depends on the size of the car. The shift to smaller and lighter cars erodes some of the value of improved crashworthiness.
From page 74...
... 62 55: A DECADE OF EXPERIENCE cars have a much greater probability of being seriously injured or killed. Occupants of subcompact cars involved in crashes with larger vehicles are from 6 to 8 times more likely to be killed than occupants of other cars (60)
From page 75...
... Highway Safety and the 55 mph Speed Limit 63 about three times as many fatal accidents per mile traveled as those aged 25 to 64 (69)
From page 76...
... 64 55: A DECADE OF EXPERIENCE Statistical analysis, discussed next, generally supports an estimate of this magnitude, although estimating what the nation's highway safety record would be without the speed limit necessarily involves speculation about numerous changes in the highway environment that have occurred since 1974, many of which were discussed earlier. Nevertheless, the current effect of the 55 mph speed limit on safety can be estimated statistically from trends in speeds, fatalities, and other key components of the highway environment.
From page 77...
... Highway Safety and the 55 mph Speed Limit 65 ment, unemployment, and labor force participation. The speed limit and the fuel shortage are accounted for with binary variables.
From page 78...
... 66 55: A DECADE OF EXPERIENCE 60 r- MODE I1:± I LEYI 40 ACTUAL 35 L 1960 1965 1970 1975 1980 1985 FIGURE 16 Fit of fatality model, 1960 to 1982, adjusting for the oil shortage and the 55 mph speed limit (72)
From page 79...
... Highway Safety and the 55 mph Speed Limit 67 TABLE 8 Correlation Between Speed Variables and Fatality Rates by State Highway System Percent Percent Exceeding Exceeding Number of Highway System 55 mph 65 mph States Statewide -- 0.02 0.27 47 Interstates -- 0.01 0.33 48 Rural arterials 0.02 0.25 45 Rural collectors 0.01 -- 0.09 37 Urban freeways -- 0.35 -- 042 14 Urban arterials -- 0.12 -- 0.08 21 Correlation significant to 0.05 variables. Because only about 3,500 fatalities occur on Interstate routes each year, random events can distort the fatality rate.
From page 80...
... 68 55: A DECADE OF EXPERIENCE Previous research has revealed wider variations in traffic speeds on individual highway segments to be related to a higher probability of accident occurrence (6,7)
From page 81...
... Highway Safety and the 55 mph Speed Limit 69 At this point, however, the extent to which speed variance affects safety independently of the mean speed remains unclear, and the extent to which motorists can increase their mean speed without increasing the variance of speed has not been demonstrated (see Appendix H)
From page 82...
... 70 55: A DECADE OF EXPERIENCE speeds continues to remain less dispersed than it was in 1973, the safety consequences of the 55 mph speed limit have not been eroded. Today, more than a decade following the inception of the 55 mph speed limit, numerous changes have reshaped driving conditions, possibly modifying the extent to which fatalities would be increased if the speed limit were increased.
From page 83...
... Highway Safety and the 55 mph Speed Limit 71 fastest growing age group among drivers, and they are more susceptible to injury in accidents, particularly high-speed crashes. The mix of traffic will become more hazardous as the share of total highway travel accounted for by heavy trucks increases.
From page 84...
... 72 55: A DECADE OF EXPERIENCE American Association of State Highway and Transportation Officials. Safety Impact of the 55 mph Speed Limit.
From page 85...
... Highway Safety and the 55 mph Speed Limit 73 State Highway Commission Joint Highway Research Program, West Lafayette, 1975.
From page 86...
... 74 55: A DECADE OF EXPERIENCE uation: A Case Study of York County Pennsylvania. Pennsylvania Department of Health, Harrisburg, Pa., June 1980.
From page 87...
... Highway Safety and the 55 mph Speed Limit 75 Limit in the United States.
From page 88...
... 4 Estimated RedUctions in Injuries and Injury Severity Although severe data limitations make firm conclusions impossible, the 55 mph speed limit appears to have reduced the number of highway injuries substantially: Between 1973 and 1974, 182,400 fewer persons were injured in highway accidents (1)
From page 89...
... Reductions in Injuries and Injury Severity 77 INJURY DATA LIMITATIONS The effect of slower driving speeds on accidents is clouded by uncertainty about the number of accidents and injuries averted because of the 55 mph speed limit. Estimating the effect of the speed limit on injuries and accidents is complicated by many of the same confounding influences that make it difficult to estimate reduced fatalities.
From page 90...
... 78 55: A DECADE OF EXPERIENCE TABLE 10 Representative Motor Vehicle Injuries by Abbreviated Injury Scale Level (2) AIS Code Injury Severity Level Representative Injuries Minor injury 2 Moderate injury 3 Serious injury 4 Severe injury 5 Critical injury Superficial abrasion or laceration of skin, digit sprain, first-degree burn, head trauma with headache or dizziness (no other neurological signs)
From page 91...
... 200 180 160 140 OTHER FEDE] L-AID PRIMARY 120 100 80 60 STA 40 1968 1970 1972 1974 1976 FIGURE 17 Injury rates on rural highways, 1968-1976 (1)
From page 92...
... 80 55: A DECADE OF EXPERIENCE Injury rates on urban highways reveal a similar pattern (Figure 18)
From page 93...
... j4'- 33( 32( 310 30( 290 U 280 270 260 250 240 230 110 100 90 80 701 I I I I I I! I I 1968 1969 1970 1971 1972 1973 1974 1975 1976 FIGURE 18 Injury rates on urban highways, 1968-1976 (1)
From page 94...
... 82 55: A DECADE OF EXPERIENCE State-Specific Data on Injury Severity Before examining actual data on the effect of the 55 mph speed limit by type of injury, it should be noted that there are a wide range of plausible hypotheses about how speed might affect the distribution of injuries. At one extreme, the reductions in speed at the time of impact could be just sufficient to reduce fatalities, but not sufficient to reduce severe or serious injuries to any great degree.
From page 95...
... TABLE 11 Driver.Injuries in North Carolina, 1973 and 1974 (8) Speed Limit Less Than 55 mph First Quarter Second Quarter Third Quarter Change Change Change Injury 1973 1974 (%)
From page 96...
... 84 55: A DECADE OF EXPERIENCE on all highways posted at 55 mph. Data in the first quarter probably include the largest confounding influences of the fuel shortage (the Arab oil embargo ended in March 1974)
From page 97...
... Reductions in Injuries and Injury Severity 85 TABLE 12 Texas Rural Highway Accidents, 1973-1974 Highway System Injury 1973 1974 Change (%) Interstate K 271 203 -- 25.1 A 838 559 -- 33.3 B 1,431 1,077 -- 24.7 C 969 778 -- 19.7 U.S.
From page 98...
... 86 55: A DECADE OF EXPERIENCE TABLE 13 Reductions in Total Statewide Injuries, 1973-1974 Injury Percent Change Category 1973-1974 Fatal -- 12.9 Incapacitating -- 11.6 Evident -- 7.8 Possible -- 8.1 SOURCE: Data for 23 states provided by the National Safety Council. Interstates and rural primary and rural state secondary highways had 102,500 fewer injuries and 6,300 fewer fatalities in 1974 (1)
From page 99...
... FATALITIES 1973 INJURIES 1973 55,113 2,835,683 Affected Highway Systems (50%) 1974 Reductions on Affected Highway Systems (-11.4%)
From page 100...
... 88 55: A DECADE OF EXPERIENCE TABLE 14 Percentage Distribution of Known Injured Survivors by AIS Category Urban Rural AIS (%)
From page 101...
... Reductions in Injuries and Injury Severity 89 ECONOMIC SAVINGS The National Highway Traffic Safety Administration (NHTSA) estimated that Americans spent $3.3 billion for medical treatment of injuries sustained in traffic accidents in 1980 (9)
From page 102...
... 90 55: A DECADE OF EXPERIENCE accidents (9)
From page 103...
... Reductions in Injuries and Injury Severity 91 TABLE 16 Direct Costs of Motor Vehicle Accidents Reduced by the 55 mph Speed Limit Estimated Savings Category ($000s) Medical 50,000-90,000 Legal 20,000-55,000 Property damage 52,000-95,000 Total 122000-240,000 highway systems directly affected by lowered speed limits.
From page 104...
... 92 55: A DECADE OF EXPERIENCE T Klein.
From page 105...
... Taxpayer Costs and Benefits Federal, state, and local governments spend more than $2 billion annually to compensate thousands of motor vehicle accident victims for medical costs or loss of earnings. Taxpayers also pay nearly $500 million in compensation and sick leave for public employees' lost time that results from accidental injuries on the highways.
From page 106...
... 94 55: A DECADE OF EXPERIENCE serious injuries and fatalities reduce the demand for medical and social service assistance to the individuals eligible for these programs. With fewer disabling accidents, and fewer individuals out of work because of their injuries, the taxes these individuals pay continue to flow into public treasuries.
From page 107...
... Taxpayer Costs and Benefits 95 and fewer fatalities and disabling injuries reduce the number of families that need public assistance. Because fewer serious accidents and injuries are experienced by public employees, overall personnel costs are reduced.
From page 108...
... 96 55: A DECADE OF EXPERIENCE TABLE 17 Direct Public Program Costs of Motor Vehicle Accidents (1983 dollars)
From page 109...
... Taxpayer Costs and Benefits 97 represent only about 2 percent of the 200,000 serious injuries that occur each year, and only a small fraction of those injured are eligible for Medicaid. Further, the majority of all injuries occur on roadways other than those posted at 55 mph (3)
From page 110...
... 98 55: A DECADE OF EXPERIENCE special education, state institutions, and the Crippled Children's Fund by some $1,000,000 annually (4)
From page 111...
... Taxpayer Costs and Benefits 99 Michigan (4)
From page 112...
... 100 55: A DECADE OF EXPERIENCE loads were only slightly greater at higher speeds, pavement damage increases exponentially with heavy axle loads, thus multiplying the effect of speed. Currently, approximately 10 to 12 percent of the federal-aid highway system has irregular surfaces that would directly contribute to a speeddeterioration relationship (6)
From page 113...
... Taxpayer Costs and Benefits 101 In 1979 the average state spent about $7.3 million to enforce the 55 mph speed limit, or roughly $10.25 million in 1983 dollars (Table 19)
From page 114...
... 102 55: A DECADE OF EXPERIENCE compare the revenues from fines to total enforcement costs (7)
From page 115...
... Taxpayer Costs and Benefits 103 TABLE 20 Total Public Program and Agency Budget Savings and Costs of the 55 mph Speed Limit (1983 dollars) Program/Budget Savings and Costs Millions ($)
From page 116...
... Energy Savings In 1973 the United States, with 6 percent of the world's population, consumed 35 percent of all the energy produced. Although the energy shortages caused by the 1973 Arab oil embargo took most Americans by surprise, many industry and government officials had been aware of the nation's growing energy problems.
From page 117...
... 20 1970 1972 1974 1976 1978 1980 1982 Energy Savings 105 FIGURE 20 Trends in petroleum imports, 1970-1983 (1, 2)
From page 118...
... 106 55: A DECADE OF EXPERIENCE to expire in April 1975 or whenever the President determined that a fuel crisis no longer existed. Although the embargo was lifted in April 1974, the President did not lift the speed restriction.
From page 119...
... Energy Savings 107 In a recent comprehensive evaluation of the energy conservation benefits of the 55 mph speed limit, Mason and Zub (6) assembled fuel performance information on 593 vehicles.
From page 120...
... 108 55: A DECADE OF EXPERIENCE speed fuel economy estimates for commercial trucks were developed by performing regression analysis on data obtained in the Double Nickel Challenge tests. The regression equation was: Fuel Consumption Rate = C1 + C2w + C30 where w is truck weight and v is selected speed (mph)
From page 121...
... 50 40 RM 10 45 50 55 60 65 70 Energy Savings 109 radua1ly increased and this translates into poorer fuel economy for the current passenger car fleet. If the 1983 fleet of passenger cars traveled at the speeds that prevailed before the 55 mph speed limit was enacted, then 1 .670,00()
From page 122...
... 9 8 55: A DECAI) F OF EXPERIENCE highways posted at 55 mph (luring the past few years.
From page 123...
... Energy Savings 111 Arab Organization of Petroleum Exporting Countries' (OPEC) sources actually rose substantially after 1973, but in the past few years it has fallen substantially (Figure 22)
From page 124...
... 7 Travel Time and Cost Impacts The slower and more uniform speeds that resulted from the 55 mph speed limit have saved lives and fuel, and have reduced the number of injuries, the nation's medical bill, and the costs of government programs. Americans have paid a price for these benefits.
From page 125...
... Travel Time and Cost Impacts 113 enactment of the 55 mph speed limit is not available, speed limit reductions were greatest on the Interstates, where daytime speeds of 75 mph had been permitted in some states (1)
From page 126...
... 114 55: A DECADE OF EXPERIENCE a living from travel for recreational or social purposes. The importance of saving time differs depending on the type of trip being made.
From page 127...
... Travel Time and Cost Impacts 115 Studies of passenger tolerance for delays during commuting suggest that most commuters ignore time losses of 2 to 4 minutes, although they probably take seriously additional time losses (4)
From page 128...
... 116 55: A DECADE OF EXPERIENCE Commercial Time Impacts Trucking In 1982 truckers drove 126.4 billion miles on highways posted at 55 mph; approximately 60 percent of this travel was on Interstates (Table 22)
From page 129...
... Travel Time and Cost Impacts 117 comparing the performance of two long-haul tractor trailers demonstrated that reducing the speed from 60 mph to 55 mph saved 10 percent of fuel consumption on hilly terrain. Reducing the speed to 50 mph, however, saved only 3 percent more fuel (5)
From page 130...
... 118 55: A DECADE OF EXPERIENCE speed for passenger cars (11)
From page 131...
... Travel Time and Cost Impacts 119 Buses Buses travel about 2.7 billion vehicle miles each year on highways posted at 55 mph. As with truck and automobile traffic, buses slowed down most on rural Interstates and less on other systems.
From page 132...
... 120 55: A DECADE OF EXPERIENCE Chapters 3 and 4 when evaluating the net desirability of the 55 mph speed limit. Comparisons of average speeds between 1973 and 1982 are inexact for all the highway systems affected by the 55 mph speed limit; nonetheless, it appears that travel in 1982 on highways posted at 55 mph required about 1 billion additional hours of passenger time when compared to the speeds of 1973 (Table 25)
From page 133...
... Travel Time and Cost impacts 121 drivers in rural areas may bear a greater share of the time cost burden than drivers elsewhere. Highway travel statistics reflect this uneven burden (18)
From page 134...
... 8.6 - 7.6 9.8 8.8 6 1' 7 f T8 17 LM 7,1 1.3.9 12.5 IPcrcct of' Ad d t j onat travel Time E Perct of Safety Rencfjrs FIGURE 24 Regional distribution of time Costs and lives saved on main rural highways.
From page 135...
... Travel Time and Cost impacts 123 carry the majority of long-distance travel, the frustration with slower travel speeds is felt most directly by users of this system. Rural Interstates also have a relatively good safety record.
From page 136...
... 124 55: A DECADE OF EXPERIENCE Westerners travel more miles on highways posted at 55 mph and encounter more open roads formerly posted at speed limits 15 and 20 mph higher. Westerners also benefit from improved safety; however, because fatal accidents have low probabilities, these benefits may not be recognized by individual motorists.
From page 137...
... Travel Time and Cost Impacts 125 Transportation Systems Center. Effect of Variation of Speed Levels on Intercity Bus Fuel Consumption, Coach and Driver Utilization and Corporate Profitability.
From page 138...
... Public Opinion Enforcement of traffic laws, as with any law, requires that most people support the basic intent of the rule. The majority of Americans, when asked whether they support or oppose the 55 mph speed limit, endorse retention of the law.
From page 139...
... Public Opinion 127 TABLE 28 Public Support of the 55 mph Speed Limit: Demographic Breakdowns, June 23-26, 1982 (1) Category Favor Oppose No Opinion Sex Male 66 32 2 Female 84 15 1 Race White 74 24 2 Nonwhite 79 20 1 Education College 74 25 1 High school 74 24 2 Grade school 77 22 1 Region East 81 17 2 Midwest 75 24 1 South 70 28 2 West 72 25 3 Age Under 30 72 26 2 30to49 73 25 2 50to64 73 26 1 Over 65 88 10 2 Income ($)
From page 140...
... 128 55: A DECADE OF EXPERIENCE TABLE 29 Preferred Speed Limit, Drivers Only (2) Question Response (mph)
From page 141...
... Public Opinion 129 TABLE 31 Preferred Speed Limit of Different Age Groups and Different Regions (2) Preferred Speed Limit (mph)
From page 142...
... TABLE 32 Attitude Toward the 55 mph Speed Limit by Amount of Driving (3) Response Strongly Somewhat Somewhat Strongly Favor Favor Opposed Opposed Question Miles Driven (%)
From page 143...
... TABLE 33 Usual Driving Speed for Those Opposed to the 55 mph Speed Limit (4) Drivers in Group Percent Usual Driving Speed Number Percentage Opposing 55 mph 55 or less 784 52.7 9.7 56-60 560 37.6 29.9 61-65 106 71 64.2 66-70 34 2.3 73.8 70 and above 5 0.3 80.0 TABLE 34 Reported Accidents Compared to Opposition to the 55 mph Speed Limit (4)
From page 144...
... 132 55: A DECADE OF EXPERIENCE TABLE 37 Support for the 55 mph Speed Limit and Frequency of Being Stopped by Police (1) 1982 1981 Question Response (%)
From page 145...
... Public Opinion 133 TABLE 39 Preferred Speed Limit and Typical Driving Speed (2) Question Responses (mph)
From page 146...
... 134 55: A DECADE OF EXPERIENCE when 75 percent of the public replied to the pollsters that they expected a 5 mph tolerance, about this same percentage of drivers on the rural Interstates (68 percent) drove within the tolerance range, although 72 percent were violating tie letter of the law.
From page 147...
... Public Opinion 135 had been stopped for speeding in 1982, results of the Gallup Poll continue to indicate strong support for the law. The polls also indicate that most people do not object to having the federal government, rather than the states, set the maximum speed limit.
From page 148...
... 9 Enforcement and Compliance Before 1974 state and local governments shared responsibility for setting and enforcing speed limits. With the establishment of the 55 mph maximum speed limit the federal government became directly involved in regulating traffic speeds by setting the maximum permissible speed.
From page 149...
... Enforcement and Compliance 137 TABLE 41 Percent of Traffic Exceeding 55 mph (average of states, unadjusted data)
From page 150...
... i r 30 to 49 Percent Exceeding ED 50 to 59 Percent Exceeding 60 to 69 Percent Exceedincr - 0 FIG U RE 25 Percentage of motor vehicles exceeding 55 mph on public highways. 1983 (unadj usted data)
From page 151...
... Enforcement and Compliance 139 During this same period of eroding compliance, a number of states weakened their penalties for violations of the 55 mph speed limit. The Congress, concerned about the enforcement efforts of these states, requested that an examination of "whether the laws of each state constitute a substantial deterrent to violations of the maximum speed limit" be undertaken by this study.
From page 152...
... 140 55: A DECADE OF EXPERIENCE All of these factors -- institutional interactions and public perceptions -- influence motorist compliance. Before addressing the question of how federal laws can most productively influence compliance, it is useful to examine four elements that influence compliance and review experience with each: (a)
From page 153...
... Enforcement and Compliance 141 below the pre-1974 maximum speed limit. This prevents drivers from being penalized by their insurance companies for speeding violations below the previous maximum limit (state laws are summarized in Appendix D)
From page 154...
... 142 55: A DECADE OF EXPERIENCE Thus, the total penalty for speeding varies widely across the states depending on the level of the fine, the court costs imposed, and the impact of a state's point system on a driver's insurance rates. Comparable data on these costs are not available.
From page 155...
... Enforcement and Compliance 143 Medium-penalty states impose one of two measures: points for speeding between 55 and 70 mph or maximum fines greater than $25 (1 state meets the first criterion and 16 meet the second) ; Lower-penalty states do not impose points for speeding violations between 55 and 70 mph and have maximum fines of $25 or less (7 states are in this category)
From page 156...
... TABLE 45 States With High and Low Penalties Rank Ordered by Level of Compliance (unadjusted data, 1983)
From page 157...
... Enforcement and Compliance 145 of citations, and by the possibility that some third factor, for example, public opinion, is affecting both the laws and the degree of compliance. Different Roads Some states post only high-quality Interstate highways at 55 mph, whereas other states have hundreds of miles of two-lane rural roadways posted at 55.
From page 158...
... 146 55: A DECADE OF EXPERIENCE speeders actually receive. The majority of state laws prohibiting speeding, like other traffic violations, establish a range of penalties that traffic judges apply at their discretion.
From page 159...
... Enforcement and Compliance 147 extremely small, because many regularly speed without being stopped. A change in their behavior requires that they believe they run an increased risk of being stopped.
From page 160...
... 148 55: A DECADE OF EXPERIENCE Texas has shown that the visibility of patrolmen has a direct effect on vehicle speeds, whereas the frequency of citations shows no relationship to speeds (7)
From page 161...
... Enforcement. and Compliance 149 Although in most states the state patrol or the state police are responsible for at least 75 percent of the enforcement of the 55 mph speed limit, in a few states enforcement is shared equally by state and local police; for example, New York and Arizona (18)
From page 162...
... 150 55: A DECADE OF EXPERIENCE Differences in regional public opinion may partly contribute to the variations in enforcement of the 55 mph speed limit in various regions of the country. The price of public approval in different states or regions may require different strictness of interpretation.
From page 163...
... Enforcement and Compliance 151 insufficiently enforcing the law, and, in response, enacted legislation in 1978 that required a specific measure of compliance based on the percentage of traffic exceeding the speed limit on all highways posted at 55 mph (20)
From page 164...
... 152 55: A DECADE OF EXPERIENCE Adjustments Allowed to State Data As directed by law in 1980 the Federal Highway Administration (FHWA) established adjustments that the states could use to lower their estimates of the percentage of statewide traffic exceeding the 55 mph speed limit.
From page 165...
... Enforcement and Compliance 153 There are an equal number of positive and negative errors, The distribution of errors is uniform rather than unimodal, and The distribution of vehicles traveling between 55 and 60 mph is uniform. The adjustments only apply to the speed data for the percent of traffic traveling between 55 and 60 mph.
From page 166...
... 154 55: A DECADE OF EXPERIENCE The assumptions that underpin the adjustments do not appear fully warranted. The only study of speedometer error for vehicles in use revealed that speedometer errors range from ± 10 mph, although the majority (90 percent)
From page 167...
... Enforcement and Compliance 155 interval based on the sample standard deviation and the size of the sample. Generally a two-tailed test is used because the error could be either positive or negative.
From page 168...
... 156 55: A DECADE OF EXPERIENCE exceeding 55 mph, whereas Texas would not be in compliance if 53.3 percent of traffic exceeded 55 mph. Obviously states such as Virginia, which have fewer sampling stations, have an advantage over other states because of their larger adjustment.
From page 169...
... Enforcement and Compliance 157 into the deterrence mechanism because of the practices of traffic courts and the police as well as the expectations of the public. Under the current standard an individual traveling at 59 mph is counted with the same weight as one speeding along at 75 mph.
From page 170...
... 158 55: A DECADE OF EXPERIENCE highway aid) if the standard is not met in any single year.
From page 171...
... Enforcement and Compliance 159 Although this is an efficient allocation for gaining compliance, from the standpoint of overall highway safety, it represents less than an optimal allocation of resources. Such allocation may imply diminished enforcement of speed limits on highways where speeding may be a more serious safety problem.
From page 172...
... 160 55: A DECADE OF EXPERIENCE Many states do not find that the 55 mph speed limit draws resources from other police responsibilities. The officers in these states, however, point out that they do not make concentrated enforcement efforts to maintain compliance.
From page 173...
... Enforcement and Compliance 161 Under such a system, the percentage of motorists exceeding the speed limit would continue to be the basis for the adjustment, but increased stress would be placed on the faster driving that increases the variance in speeds and most impairs safety. Under this approach, a state in which 100 percent of motorists traveled at 57 mph would score 100 points (1 point x 100 percent)
From page 174...
... 162 55: A DECADE OF EXPERIENCE CONCLUSION Part of the impetus for this study came from congressional concern about states that enacted low fines for offenders of the 55 mph speed limit. Whether such practices have an effect on speeds and safety remains uncertain.
From page 175...
... Enforcement and Compliance 163 levels of enforcement. It is not clear whether the majority of the public would continue to support the speed limit if enforcement increased dramatically.
From page 176...
... 164 55: A DECADE OF EXPERIENCE A more risk-related weighing scheme of the type proposed in this chapter would encourage law enforcement agencies to allocate their resources so as to reduce the points consumed against them. This means that proportionally more resources would be directed at high-speed offenders and off-Interstate offenders.
From page 177...
... Enforcement and Compliance 165 F Council.
From page 178...
... 10 Recommendations and Conclusions The 55 mph national maximum speed limit, enacted during the Arab oil embargo of 1973 to conserve fuel, became effective in all states by March 1974. Motorists slowed down and the number of highway fatalities declined from 55,511 to 46,402 per year -- an unprecedented decrease in highway fatalities outside of wartime.
From page 179...
... Recommendations and Conclusions 167 injuries and 34,000 to 61,000 fewer minor and moderate injuries occur each year because of slower and more uniform speeds. As a result of fewer injuries, medical costs are reduced by some $50 to $90 million annually (Chapter 4)
From page 180...
... 168 55: A DECADE OF EXPERIENCE TABLE 48 Current Impact of the 55 mph Speed Limit (1, 2) Reduction due Total to 55 mph Speed Percent Major Impact Areas (1983)
From page 181...
... Recommendations and Conclusions 169 TABLE 49 Total Travel and Fatalities on Highways Posted at 55 mph (1982) Urban Rural Vehicle Vehicle Miles of Miles of Highway Travel Total Travel Total System (millions)
From page 182...
... 170 55: A DECADE OF EXPERIENCE Residents in rural areas tend to depend more on automobile travel and tend to spend more of their time driving on highways posted at 55 mph. Motorists in the Mountain West region of the country spend 15 percent of their travel time on rural Interstates as compared to only 6 percent by motorists in the Northeast.
From page 183...
... Recommendations and Conclusions 171 way systems, and public attitudes favoring return of speed-limit jurisdiction entirely to the state and local governments?
From page 184...
... 172 55: A DECADE OF EXPERIENCE the sampling methods from which estimates are drawn. Nonetheless, given the sharp discontinuity from past trends (discussed in Chapter 2)
From page 185...
... Recommendations and Conclusions 173 increase in the number of motorists exposed to risk -- suggests that the speed limit saves 2,000 to 4,000 lives annually. Although these mechanical adjustments oversimplify the complexity of the safety trends of the last decade, they illustrate that in approximate terms the benefits of the speed limit remain large.
From page 186...
... 174 55: A DECADE OF EXPERIENCE without being ticketed. In doing so they consider themselves in compliance with the spirit of the law.
From page 187...
... Recommendations and Conclusions 175 violation of the law leads to disrespect of laws generally -- involve forecasts and value judgments that are unavoidably controversial.
From page 188...
... 176 55: A DECADE OF EXPERIENCE TABLE 51 Motor Vehicle Fatalities on All Roads and on Highways Posted at 55 mph (1982) Highway Type Total Number Percent of Total All roads and highways 43,721 100.0 Highways posted at 55 mph 21,658 49.5 Non-Interstate freeways 740 1.7 Arterials 9,633 22.0 Collectors/local 7,658 17.5 Urban Interstates 1,644 3.8 Rural Interstates 1,983 4.5 NOTE: Estimates of fatalities on highways posted at 55 mph provided by the Center for Statistics and Analysis, National Highway Traffic Safety Administration, U.S.
From page 189...
... Recommendations and Conclusions 177 ways would require 445 million fewer hours annually. This means that.
From page 190...
... 178 55: A DECADE OF EXPERIENCE TABLE 53 Comparative Speed Trends on Highways in North Carolina for Highways With and Without Changes in Posted Speed Limits (6) Pre-55 mph Post-55 mph Speed Limit Speed Limit (April 1973)
From page 191...
... Recommendations and Conclusions 179 that might not have been achieved otherwise. By requiring the states to conform to a national standard for maximum speeds, the federal government entered an area of policymaking previously occupied by state and local governments.
From page 192...
... 180 55: A DECADE OF EXPERIENCE Could higher speed limits, if allowed on some roads, be contained to eligible routes? Is control of speed limits a state or a federal responsibility?
From page 193...
... Recommendations and Conclusions 181 Safety, 1980.
From page 194...
... Appendix A Effect of the Fuel Shortage on Recreational Travel in 1974 With the onset of the fuel shortage in late 1973 many people postponed vacations and reduced recreational trips. Vacation travel, especially longdistance driving on unfamiliar roads, may be more hazardous than routine trips for work or shopping.
From page 195...
... 183 FLORIDA The energy crisis of 1974 represented a clear break in the long-term trend in recreational travel growth in Florida. Recreational travel declined by 4.8 percent in 1974, only slightly more than the statewide travel decline of 4.65 percent.
From page 196...
... TABLE A -- i Number of Tourists Traveling by Car in Florida, Quarterly Data Percent Percent Percent Change Change Change No.
From page 197...
... 185 TABLE A-2 Quarterly Decline in Fatalities and Tourism, 1974 Percent Change Percent Change Quarter in Tourism in Fatalities 1st -18.8 -20.5 2nd -10.5 -15.7 3rd +7.0 -11.7 4th +2.3 -10.5 TABLE A-3 Washington State Tourism Data, Monthly Change in Fatalities and Tourism Travel, 1973-1974 Total Recreational Travel '000 Month 1973 1974 Percent Change in Tourism Percent Change in Fatalities January 616 510 -17.2 -6.0 February 899 588 -34.6 -7.0 March 1,207 930 -23.0 -13.8 April 1,705 1,665 -2.4 -52.1 May 3,281 2,961 -9.8 -30.3 June 3,457 4,507 +30.4 +4.1 July 5,452 5,505 +1.0 + 11.8 August 4,852 6,059 +24.9 -10.0 September 2,266 2,610 +12.9 +4.8 October 954 1,277 +32.9 +34.4 November 527 667 +26.6 +22.4 December 429 547 +27.5 + 17.0 Total 23,645 27,526 TABLE A-4 House Trailer Visits to Washington State Parks Month 1973 1974 Percent Change January 2,573 1,189 -53.8 February 14,577 5,218 -64.2 March 26,948 5,578 -79.3 April 60,608 43,611 -28.0 May 80,511 92,338 +12.8 June 127,675 184,475 +44.5 July 234,670 267,822 + 14.2 August 231,925 322,787 + 39.2 September 72,039 126,208 +75.2 October 21,478 48,384 + 125.3 November 6,115 11,747 +92.1 December 2,611 4,200 +61.1 Total 879,730 1,120,422 + 21.5
From page 198...
... 186 was down 27.9 percent in the first quarter for Saturday and Sunday. Overall the Washington state data indicate that recreational travel declined more steeply than total travel.
From page 199...
... Appendix B Effectiveness of Safety Belts in Reducing Highway Fatalities Safety belts have been in existence nearly as long as automobiles. The first patent for leather straps to restrain the occupants of a motorized vehicle dates to 1885.
From page 200...
... 188 to unbelted occupants. A few studies, however, have applied a clinical, or case study approach in which medical researchers reconstruct crashes to estimate whether a belted occupant would have had a less severe injury.
From page 201...
... 189 TABLE A-5 Effectiveness of Lap-Shoulder Safety Belts in Reducing Moderate and Severe Injuries (4) Injury Moderate or Worse Severe or Worse Vehicle Damage - Minor 53-56 43-46 Moderate 58-60 65-66 Moderate/severe 46-55 36-62 Severe 44-51 39-49 Age of Occupant 10-25 48 50 26-55 53 41 56+ 59 53 Crash Type Front 39 Side 58 - Rear 61 - Rollover 65 - Vehicle Type Subcompact 52 - Compact 52 - Intermediate 45 - Full-sized 60 - olnsufficient sample size for estimation CLINICAL ANALYSES A less frequently applied method of analyzing the effectiveness of safety belts has relied on expert judgment.
From page 202...
... TABLE A-6 Safety Belt Effectiveness Studies (5) Author Year Type of Belt Reduction in All Types of Injuries (%)
From page 203...
... 191 are only about one-half as likely to be involved in the most severe crashes. They compared the probability of accident involvement for belted and unbelted drivers (26)
From page 204...
... 192 accidents are most likely to occur. Motorists may not realize these potential safety benefits, as is evident by the low percentage of U.S.
From page 205...
... TABLE A-7 International Mandatory-Use Laws and Estimates of Use (27-30) Date Jurisdiction Of Law Pre-Law Use Post Law Use Most Recent Estimate Combined Urban- Urban Rural Rural Combined Type' Urban- Enforce- Urban Rural Rural ment (%)
From page 206...
... 194 Germany, the initial increases in compliance appear to have been sustained. Whereas New Zealand relies on intermittent enforcement, West German drivers appear to wear safety belts voluntarily.
From page 207...
... 195 Rates for use of safety belts are typically much lower for teenagers, drivers af night, and drivers who have been drinking, all of whom have a higher probability of involvement in an accident. This implies that the effectiveness of safety belts does not increase linearly with compliance.
From page 208...
... 196 fatality is reduced by about 50 percent. Translated to the United States, this could mean a dramatic reduction in the number of vehicle-occupant fatalities.
From page 209...
... 197 of the law depends on the treatment of the topic in the media and the awareness gained through public information in publicity campaigns. Campaigns underway at the national, state, and local levels could help convince individuals of the merits of safety belts and increase support for a law mandating their use.
From page 210...
... 198 D.C. Andreassand.
From page 211...
... 199 R.A. Wilson and C.M.
From page 212...
... Appendix C Speeding and Highway Fatalities SUMMARY AND RESULTS This appendix was written by Charles A Lave, Professor of Economics, University of California, Irvine.
From page 213...
... 201 is a high speed or a low speed, the fatality rate is low; presumably because the probability of collision is low. When there is a considerable range of speeds among cars on the highway, the fatality rate is high; presumably because this increases the probability of collision.
From page 214...
... TABLE A-8 Means of the Variables Highway System Fatality Rated Average Speed (mph) Percent Drivers Exceeding 55 mph Percent Drivers Exceeding 65 mph 85th Percentile Speed (mph)
From page 215...
... 203 TABLE A-9 Range of Variation Among States Variable Mean Lowest Value Highest Value Urban Freeways Fatality rate 3.25 0.89 15.50 Average speed 54.90 51.10 57.20 Percent drivers exceeding 55 mph 46.30 23.10 64.60 Percent drivers exceeding 65 mph 2.94 0.40 8.10 85th percentile speed 59.90 57.40 63.80 85th percentile -average speed 5.00 1.80 7.50 Citations per driver 58.20 24.10 118.00 Rural Interstates Fatality rate 1.81 0.39 4.79 Average speed 58.10 54.80 62.50 Percent drivers exceeding 55 mph 68.70 40.30 88.80 Percent drivers exceeding 65 mph 9.31 1.70 28.60 85th percentile speed 63.20 58.80 69.40 85th percentile -average speed 5.13 2.70 9.10 Citations per driver 74.00 24.10 193.00 Considerable difference exists among states. The data in Table A-9 indicate this range of variation for two subsets of the data: Interstate rural roads in 1981 and urban freeways in 1981.
From page 216...
... 204 TABLE A-10 Effect of Speed on Fatality Rates Highway Systems i-Ratio of Average Speed 1981 Rural Interstate ( 0.4) Arterial (-2.3)
From page 217...
... 205 cates that increased average speeds decrease the fatality rate. To understand the insignificance of the speed variables in these equations and the perverse signs of the speed variables in other equations, it is useful to construct a simple algebraic model of the effects of speed.
From page 218...
... 206 TABLE A-li Combined Effects of Speed and Speed Variance Highway System Average Speed 85th Percentile Speed R2 1981 Rural Interstate -0.24 (1.8)
From page 219...
... 207 on the fatality rate. It is obvious, from Table A-12, that this is not true.
From page 220...
... 208 Would raising the speed limit raise the variance and the fatality rate to their former levels? Perhaps it would; perhaps not.
From page 221...
... Appendix D State Penalties For Violation of the 55 mph Speed Limit State Penalties for Exceeding Pre-55 mph Speed Limit Penalties for Exceeding 55 mph Speed Limit Alabama $100 fine maximum, no points assessed. And/or Jail Conviction Fine Maximum Maximum first $5 to $100 10 days second $200 20 days third $500 6 months (within I yr)
From page 222...
... APPENDIX D (continued) State Penalties for Exceeding Pre-55 mph Speed Limit Penalties for Exceeding 55 mph Speed Limit California Same as present.
From page 223...
... Idaho 'Up to $100 fine and/or up to 10 days imprisonment. $5 fine maximum plus $7.50 costs, no points, nonmoving violation for insurance.
From page 224...
... APPENDIX D (continued) State Penalties for Exceeding Pre-55 mph Speed Limit Penalties for Exceeding 55 mph Speed Limit Louisiana First offense, up to $100 fine and/or up to 30 days imprisonment.
From page 225...
... Mississippi Unless another penalty is provided fine is: first conviction, not more than $100 or more than 10 days; second conviction within 1 year, fine not more than $200 or more than 20 days or by both; third or subsequent conviction within 1 year after first conviction, fine not more than $500 or not more than 6 months or both. Missouri Up to $500 fine and/or up to 1 year imprisonment.
From page 226...
... APPENDIX D (continued) State Penalties for Exceeding Pre-55 mph Speed Limit Penalties for Exceeding 55 mph Speed Limit New York Up to $100 fine and/or up to 30 days imprisonment.
From page 227...
... Oregon $500 fine maximum. Up to 1 year imprisonment Pennsylvania $10 fine regardless of speed plus $5 court cost; total penalty $15.
From page 228...
... APPENDIX D (continued) State Penalties for Exceeding Pre-55 mph Speed Limit Penalties for Exceeding 55 mph Speed Limit South Dakota Up to $100 fine.
From page 229...
... Washington Maximum fine $250; Maximum jail term, 90 days. West Virginia First offense: maximum fine $100 not more than 10 days in jail.
From page 230...
... Appendix E Analysis of Speedometer Adjustments The analysis of speedometer adjustments in this appendix is provided by John J Wiorkowski, Professor, Programs in Mathematical Science, University of Texas, Dallas.
From page 231...
... 219 Assume that the counting device can measure the proportion of cars traveling at speed x, and denote this by f(x)
From page 232...
... 220 Equation 3 to sum over k. To do this, specific speeds must be examined.
From page 233...
... 221 Now Equation 4 can be rewritten as 5 (max-55)
From page 234...
... 222 be written as Pr(y > 55)
From page 235...
... 223 of faulty speedometers are in reality not speeding, are not counted. This might seem reasonable except that the NHTSA-FHWA memorandum states, "The assumption is that a driver who knowingly exceeds the speed limit should be included in the 'percent exceeding' statistic calculation." Thus, individuals are incorrectly excluded.
From page 236...
... Due to limited data available on speedometer error distributions and frequency distributions of vehicle speed, any methodology for calculating speedometer errors must be based upon a set of reasonable assumptions. The following illustrates one methodology accompanied by a given set of assumptions.
From page 237...
... Appendix F Survey of State Traffic Enforcement Administrators To supplement available national data on speed-limit enforcement efforts, the state agencies responsible for enforcement of the 55 mph speed limit were surveyed. Thirty-eight states responded, although not all surveys contained complete information.
From page 238...
... 226 of the time spent enforcing only the 55 mph speed limit are not available. Indeed, some states could not provide estimates of the amount of time spent patroling different types of highways.
From page 239...
... 227 TABLE A-17 Comparison of Staff-Hour Allocations with Travel and Motor Vehicle Fatalities on Highways Posted at 55 mph Manhours Travel Fatalities Highway System (%)
From page 240...
... 228 only 13 percent of police officers but issued 75 percent of all speeding citations for violations of the 55 mph speed limit. He indicated that speed-limit enforcement was not a priority for local agencies.
From page 241...
... 229 for patrolmen to increase speed-limit enforcement, which allows the agency to increase the number of patrols without hiring additional personnel. One state official indicated that 20 percent of 55 mph enforcement is achieved through overtime pay.
From page 242...
... 230 ance that officers should permit before writing a citation. These tolerances are given in the table below.
From page 243...
... 231 police chiefs allocated 29 percent to additional staff hours for enforcement of the 55 mph speed limit and 12.6 percent to capital budgets (mostly for additional speed-monitoring equipment and vehicles)
From page 244...
... Appendix G Estimates of Taxpayer Benefits OLD AGE, SURVIVORS, AND DISABILITY INSURANCE Total Old Age, Survivors, and Disability Insurance (OASDI) costs come from three separate programs: lump sum awards, survivors benefits, and disability insurance.
From page 245...
... 233 Calculation [3000 x (0.73)
From page 246...
... 234 Disability Benefits [Number AIS 4 and 5 injuries averted] x [Proportion by Sex]
From page 247...
... 235 Medicaid Savings = $66,090,000 x [Proportion population receiving Medicaid]
From page 248...
... 236 x [Average Annual Benefit] x [Administrative Adjustment]
From page 249...
... 237 Workmen's Compensation Federal savings = [Number of Injuries] x [Proportion of Severe Injuries Occurring to Federal Workers]
From page 250...
... 238 State [Time Lost] (see estimates above)
From page 251...
... 239 NHTSA, U.S. Department of Transportation, 1983, p.
From page 252...
... Appendix H Further Research During the course of this study the Committee for the Study of Benefits and Costs of the 55 mph National Maximum Speed Limit encountered a number of instances where necessary data were either inadequate or nonexistent. In other instances, the data were available, even if scattered, but had never been properly analyzed and it was not feasible to assemble and process such data for this study.
From page 253...
... 241 at 55 mph, a sample of vehicle speeds should be taken on highways posted below 55 mph. This resulting information will allow better estimation of the relationship between speed and safety, and will help determine if restricted speeds on well-patroled roads posted at 55 mph are causing motorists to drive faster on less safe systems where there is less likelihood that they will be apprehended.
From page 254...
... 242 highway safety, and further analysis is needed to determine whether average speed could be increased independently of speed variance, while accounting for the physical and behavioral factors involved. SAFETY AND TRAVEL PURPOSES The belief that recreational driving, which is more prone to random fluctuations than routine trips, is inherently more dangerous is alluded to in this study.
From page 255...
... 243 ENFORCEMENT ISSUES More research is needed on the question of how motorist perceptions of enforcement affect compliance and how to best influence those perceptions. One important factor influencing deterrence is the role of traffic courts in meting out fines for speed-limit violators.
From page 256...
... Appendix I Detailed Tables TABLE A-21 Fatality Rate (per 100 million vehicle miles) , 1946-1983 Year Rate Percentage Change Year Rate Percentage Change 1946 9.8 -12.65 1965 5.54 -1.60 1947 8.82 -10.00 1966 5.70 +2.89 1948 8.11 -8.05 1967 5.50 -3.51 1949 7.47 -7.89 1968 5.40 -1.82 1950 7.59 -1.61 1969 5.21 -3.52 1951 7.53 -0.79 1970 4.88 -6.33 1952 7.36 -2.26 1971 4.57 -6.35 1953 6.97 -5.30 1972 4.43 -3.06 1954 6.33 -9.18 1973 4.24 -4.29 1955 6.34 +0.16 1974 3.59 -15.33 1956 6.28 -0.95 1975 3.45 -3.90 1957 5.98 -4.78 1976 3.33 -3.48 1958 5.56 -7.02 1977 3.35 +0.60 1959 5.41 -2.70 1978 3.39 +1.19 1960 5.31 -1.85 1979 3.50 +3.20 1961 5.16 -2.82 1980 3.50 0.00 1962 5.32 +3.10 1981 3.32 -5.14 1963 5.41 + 1.69 1982 2.93 -11.75 1964 5.63 +4.07 1983 2.76 -5.80 SOURCE: National Safety Council.
From page 257...
... 245 TABLE A-22 Average Speeds on Selected Highways, 1973-1983 Change 1973 1974 in Average Average Speed Speed Speed 1973-74 Highway System (mph)
From page 258...
... 246 TABLE A-24 Estimated Distribution of Nonfatal Injuries by Maximum AIS by Highway Class 1982° Highway System AIS 1 (%)
From page 259...
... TABLE A-25 Estimated Reductions in Injuries by AIS Level and Highway .Typea, 1973-1974 AIS 1 AIS 2 AIS 3 AIS 4 AIS 5 Highway Classificationb 1973 1974 Change 1973 1974 Change 1973 1974 Change 1973 1974 Change 1973 1974 Change Urban Interstates and 121,539 101,282 20,957 18,879 15,733 3,146 5,896 4,913 983 691 576 115 30 25 5 freeways Rural Interstates 60,351 41,817 18,534 19,053 13,208 5,854 7,275 5,029 2,246 577 399 178 184 122 62 Rural other federal-aid 235,016 201,444 33572 50,016 42,872 7,144 17,201 14,744 2,457 1,830 1,568 262 915 784 131 primary Rural federal-aid state 140,028 133,877- 6,151 23,695 22,655 1,040 11,502 10,997 505 1,258 1,203 55 744 711 33 Total reductions 79,214 17,184 6,191 610 231 'These calculations assume 1973 and 1974 total injuries are distributed according to the injury distributions given in Table A-24. bEstimates of total nonfatal injuries by highway type from Fatal and Injury Accident Rates on Federal-Aid and Other Highway Systems, 1975 FHWA, U.S.
From page 260...
... 248 TABLE A-26 Petrolum Imports and Domestic Petroleum Production, Selected Years 1960-1980 (000s BPD) Year Domestic Production Crude Oil Total Imports, Refined Petroleum Products Crude Oil Domestic Petroleum Consump- tionb Imports as a Percentage of Domestic Consumption 1960 7,989 1,820 c _C 9,825 18.5 1970 11,312 3,419 _C _C 14,696 23.2 1973 9,208 6,256 3,012 3,244 17,308 36.1 1974 8,774 6,112 2,635 3,477 16,653 36.7 1975 8,375 6,056 1,951 4,105 16,322 37.1 1976 8,132 7,313 2,026 5,287 17,461 41.9 1977 8,245 8,807 2,193 6,615 18,431 47.8 1978 8,707 8,363 2,008 6,356 18,847 44.4 1979 8,552 8,456 1,937 6,519 18,513 45.7 1980 8,597 6,909 1,646 5,263 17,056 40.5 1981 8,572 5,996 1,599 4,396 16,058 37.3 1982 8,649 5,113 1,625 3,488 15,296 33.4 1983" 8,664 4,935 1,629 3,306 15,004 32.9 SOURCE: H.R.
From page 261...
... TABLE A-27 Effect of Weight on Passenger Car Fuel Consumption by Inertia Weight Class" Inertia Weight Class (Ib) Fuel Consumption Rate at 55 mph (gal/mile)
From page 262...
... 250 TABLE A-28 Estimated Highway Fuel Consumption Rates for Passenger Cars Fuel Consumption Fuel Consumption Percent of Rate for 1972 Rate for 1979 Travel Mileage Fleet Fleet Model Year by Model Year (gal/mile) (gal/mile)
From page 263...
... 251 TABLE A-29 Estimated Fuel Consumption and Fuel Economy Rates of 1983 Passenger Automobile Fleet for Before and After the 55 mph Speed Limit° Model Year Percent of Annual Mileage by Model Year Fuel Consumptionb Pre- 1974 Post- Gall 1974 Mile MPG Gal/Mile MPG.
From page 264...
... 252 TABLE A-30 Crude Oil and Petroleum Product Imports (000s BPD) Arab OPEC as a Total Percent Total Arab Total of Total Year OPEC OPEC Non-OPEC Imports Imports 1973 2,993 915 3,263 6,256 14.6 1974 3,280 752 2,832 6,112 12.3 1975 3,601 1,383 2,454 6,055 22.8, 1976 5,066 2,424 2,247 7,303 33.2 1977 6,193 3,185 2,614 8,807 36.2 1978 5,751 2,963 2,613 8,364 35.4 1979 5,637 3,056 2,819 8,456 36.1 1980 4,300 2,551 2,609 6,909 36.9 1981 3,323 1,848 2,672 5,995 30.8 1982 2,146 854 2,968 5,114 16.7 1983 1,676 483 3,120 4,796 10.1 SOURCE: Monthly Energy Review.
From page 265...
... 253 TABLE A-32 Estimated Average Speeds for Passenger Vehicles, 1973 and 1982 (1)
From page 266...
... 254 TABLE A-34 Additional Passenger Hours of Travel Additional Additional Passenger Vehicle Hours Occupancy Hours (OOOS) a Ratesb (000s)
From page 267...
... Study Committee Biographical Information ALAN A ALTSHULER, Chairman, is a political scientist and is currently Dean of the Graduate School of Public Administration, New York University.
From page 268...
... 256 He holds a B.A. in economics and a masters degree in public service from California State University at Los Angeles.
From page 269...
... 257 Laboratory 1955-1961, taught physics at the University of Illinois, Urbana, 1961-1970, and served as Director, Coordinated Science Laboratory, University of Illinois, 1965-1970. He is a recipient of the U.S.
From page 270...
... FM sion; Special Assistant to the Assistant Secretary for Systems Development and Technology; and Manager, Advanced Research Program.
From page 271...
... 259 motive Engineers and received the Arch T Colman paper award in 1974 and 1975, and the Vincent Bendix Automotive Electronics Award 1976.
From page 272...
... 260 University of New York, Buffalo, 1980-1983. He has served on the following Transportation Research Board Committees since 1970: Traffic Records; Operator Regulations; and Alcohol, Other Drugs, and Transportation.
From page 273...
... 261 psychology and automobile crashworthiness, one of which received the Arch T Coleman award from the Society of Automotive Engineers.
From page 274...
... 262 graduate of the University of Texas with a B.S. in mechanical engineenng, Mr.
From page 275...
... The Transportation Research Board is a unit of the National Research Council, which serves the National Academy of Sciences and the National Academy of Engineering. The Board's purpose is to stimulate research concerning the nature and performance of transportation systems, to disseminate the information produced by the research, and to encourage the application of appropriate research findings.
From page 276...
... TRANSPORTATION RESEARCH BOARD NATIONAL RESEARCH COUNCIL .2101 Constitution Avenue, N.W. Washington, D.C.

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