National Academies Press: OpenBook

A Guide for Reducing Speeding-Related Crashes (2009)

Chapter: Section I - Summary

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Suggested Citation:"Section I - Summary." National Academies of Sciences, Engineering, and Medicine. 2009. A Guide for Reducing Speeding-Related Crashes. Washington, DC: The National Academies Press. doi: 10.17226/14227.
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Suggested Citation:"Section I - Summary." National Academies of Sciences, Engineering, and Medicine. 2009. A Guide for Reducing Speeding-Related Crashes. Washington, DC: The National Academies Press. doi: 10.17226/14227.
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Suggested Citation:"Section I - Summary." National Academies of Sciences, Engineering, and Medicine. 2009. A Guide for Reducing Speeding-Related Crashes. Washington, DC: The National Academies Press. doi: 10.17226/14227.
×
Page 3
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Suggested Citation:"Section I - Summary." National Academies of Sciences, Engineering, and Medicine. 2009. A Guide for Reducing Speeding-Related Crashes. Washington, DC: The National Academies Press. doi: 10.17226/14227.
×
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Suggested Citation:"Section I - Summary." National Academies of Sciences, Engineering, and Medicine. 2009. A Guide for Reducing Speeding-Related Crashes. Washington, DC: The National Academies Press. doi: 10.17226/14227.
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SECTION I Summary Introduction One of the hallmarks of the AASHTO Strategic Highway Safety Plan (SHSP) is to approach safety problems in a comprehensive manner. The range of strategies available in the guides covers various aspects of the road user, the highway, the vehicle, the environment, and the management system. The guides strongly encourage the user to develop a program to tackle a particular emphasis area from each of these perspectives in a coordinated manner. To facilitate this, the electronic form of the material uses hypertext linkages to enable seamless integration of various approaches to a given problem. As more guides are developed for other emphasis areas, the extent and usefulness of this form of implementation will become even more apparent. The goal is to move away from independent activities of engineers, law enforcement, educators, judges, and other highway-safety specialists. The implementation process outlined in the guides promotes the formation of working groups and alliances that represent all of the elements of the safety system. In so doing, they can draw upon their combined expertise to reach the bottom-line goal of targeted reduction of crashes and fatalities associated with a particular emphasis area. The six major areas of the AASHTO SHSP (Drivers, Vehicles, Special Users, Highways, Emergency Medical Services, and Management) are subdivided into 22 goals, or key emphasis areas, that impact highway safety. Though reduction of speeding-related fatalities is not specifically included in the list of SHSP emphasis areas, speeding is a contributing factor in many fatal crashes. Therefore this guide, which addresses speeding, complements the other guides in this series. Strategies discussed are applicable to high- and/or low-speed roadways and include education, enforcement, and engineering approaches to reducing speeding-related fatalities. Speeding is among the most significant contributing factors to fatal collisions. Excessive speeds reduce a driver’s ability to react and maneuver and require greater stopping distances. The severity of collisions, particularly those involving pedestrians, bicyclists, and motorcyclists, increases dramatically with the speed of collision. Speeding-related crashes are an issue that can be deterred with increased efforts in education, engineering, and enforcement. Currently there are many different efforts in the nation and around the world in practice to reduce these types of collisions. Throughout this guide, problems and strategies associated with “low-speed” and “high- speed” roads are presented. AASHTO considers (AASHTO Policy on Geometric Design of Highways and Streets, 5th Edition) the upper limit for low-speed design (i.e., design speed) is 45 mph, and the lower limit for high-speed design is 50 mph. Many of the strategies involve speed limits and advisory speeds (setting, posting, enforcing, etc.). As it is common practice for posted speed limits to be some nominal value less than the design speed (often 5 mph), this guide presents information on high- I-1

and low-speed designs, with the definition being low-speed roads with speed limits of 40 mph or less (5 mph less than the highest AASHTO design speed) and high-speed roads with speed limits of 45 mph or greater (5 mph less than the lowest AASHTO design speed). Grouping of strategies by speed range is done for convenience and focus. Users of this guide need not be constrained, however, by the definitions and groupings. A user may find that a strategy discussed in the low-speed guide may have application and value in a nominally high-speed condition. This is not only acceptable but considered good use of the guide. The strategies discussed are shown in Exhibit I-1. General Description of the Problem Excessive or inappropriate speeds result from two basic problems, both of which involve human factors considerations. Driver behavior (i.e., consciously choosing a clearly inappropriate speed) is one aspect of the problem. The second is associated with driver response to the environment (i.e., inadvertent selection of a speed that is inappropriate or unsafe, failure to adjust or change speeds, or failure to perceive the speed environment and as a result incur risk of a collision or conflict). It is both of these types of problems that this guide seeks to address. Approximately 42,000 automobile-related fatalities occur each year in the United States, and historically, nearly one-third of fatal crashes involve speeding, as shown in Exhibit III-1. In Traffic Safety Facts 2006—Speeding, the National Highway Transportation Safety Administration (NHTSA) defines a speeding-related crash as a crash in which “the driver was charged with a speeding-related offense or if an officer indicated that racing, driving too fast for conditions, or exceeding the posted speed limit was a contributing factor in the crash” (NHTSA, 2006). This section details characteristics of speeding-related fatalities and fatal crashes obtained from a review of recent literature and the NHTSA Fatality Analysis Recording System (FARS) database. In 2006, there were 42,708 traffic fatalities, 30 percent (13,113) of which involved speeding. Of these fatalities, 13,543 (32%) occurred as a result of a speeding-related crash. Only 13% of all speeding-related traffic fatalities occurred on Interstate roadways, while 72% occurred on non-Interstate roads. Of the crashes on non-Interstate roads, 29% occurred on low-speed non-Interstate roads (defined for the purpose of this report as roads with a speed limit of 40 mph or less), and 43% occurred on high-speed non-Interstate roads (roads with a speed limit of 45 mph or more). Roadways with unknown or no statutory speed limits accounted for 15 percent of speeding-related fatalities. These data are taken from Traffic Safety Facts 2006–Speeding (NHTSA, 2006). A further review of 2005 FARS data yields additional insights into fatal crash characteristics (NHTSA, 2005): • Approximately 39 percent of speeding-related fatal crashes occurred on horizontal curves. • Speeding-related fatalities occur primarily in single-vehicle crashes; 70 percent of speeding-related fatalities on low-speed roads, and 67 percent on high-speed roads occurred in this manner of collision. • 38 percent of speeding drivers in a fatal crash were under the age of 25. • 40 percent of drivers that were speeding in fatal collisions had a blood alcohol content (BAC) of at least 0.08. SECTION I—SUMMARY I-2

SECTION I—SUMMARY I-3 Objectives of the Emphasis Area The speeding-related safety issues discussed above are the basis for the inclusion of the strategies discussed in Section V. The strategies cover setting appropriate speed limits, improving driver awareness of speeding-related safety concerns, improving enforcement efforts, communicating appropriate speeds with drivers, and ensuring the roadway environment is designed and operated so as to encourage appropriate speeds. The strategies are grouped by objective—the safety concerns being addressed. Exhibit I-1 lists the objectives and the related strategies discussed in this guide. The strategies considered cover the full range of engineering, enforcement, and education: • Set appropriate speed limits—Speed limits that appear inconsistent may be ignored by the majority of drivers and this may contribute to lack of respect for speed limit and other traffic laws. Setting speed limits to reflect the surrounding context of the roadway and meet with driver expectations can help improve driver respect for speed limits. • Heighten driver awareness of speeding-related safety issues—Informing drivers of the risks—both to themselves and to other road users—associated with speeding is intended to encourage drivers to obey speed limits and drive at speeds safe for the roadway environment. EXHIBIT I-1 Objectives and Strategies for Addressing Speeding-Related Fatalities Objectives Strategies A. Set appropriate speed limits B. Heighten driver awareness of speeding-related safety issues C. Improve efficiency and effective- ness of speed enforcement efforts A1 Set speed limits which account for roadway design, traffic, and environment A2 Implement variable speed limits A3 Implement differential speed limits for heavy vehicles if appropriate (High Speed Only) B1 Increase public awareness of risks of driving at unsafe speeds B2 Increase public awareness of potential penalties for speeding B3 Increase public awareness of risks of not wearing seatbelts B4 Implement neighborhood speed watch/traffic management programs (Low Speed Only) B5 Implement Safe Community Programs C1 Use targeted conventional speed enforcement programs at locations known to have speeding-related crashes C2 Implement automated speed enforcement C3 Increase penalties for repeat and excessive speeding offenders C4 Strengthen the adjudication of speeding citations to enhance the deterrent effect of fines C5 Increase fines in special areas

SECTION I—SUMMARY I-4 D. Communicate appropriate speeds through use of traffic control devices E. Ensure that roadway design and traffic control elements support appropriate and safe speeds EXHIBIT I-1 (Continued) Objectives and Strategies for Addressing Speeding-Related Fatalities Objectives Strategies D1 Improve speed limit signage D2 Implement active speed warning signs D3 Use in-pavement measures to communicate the need to reduce speeds D4 Implement variable message signs (High Speed Only) E1 Use combinations of geometric elements to control speeds E2 Effect safe speed transitions through design elements and on approaches to lower speed areas E3 Provide appropriate intersection design for speed of roadway E4 Provide adequate change + clearance intervals at signalized intersections E5 Operate traffic signals appropriately for intersections and corridors (signal progression) E6 Provide adequate sight distance for expected speeds E7 Implement protected-only signal phasing for left turns at high- speed signalized intersections (High Speed Only) E8 Install lighting at high-speed intersections (High Speed Only) E9 Reduce speeds and/or volumes on both neighborhood and downtown streets with the use of traffic calming and other related countermeasures (Low Speed Only) • Improve the effectiveness of speed enforcement efforts—Many crashes are caused or aggravated by drivers’ noncompliance with traffic control devices or traffic laws. Effec- tiveness of enforcement can be increased if drivers perceive there is a significant chance they may be cited for speeding and may be given a hefty fine. Visible conventional or automated enforcement programs, increased fines for repeat offenders, and upholding of citations and levying of fines by courts can increase drivers’ perceptions of the enforcement- related risks of speeding. • Communicate appropriate speeds through use of traffic control devices—Information on appropriate speeds, including permanent speed limits, variable speed limits, and warning speeds, needs to be conveyed clearly to drivers and at appropriate locations. Pavement markings can be used to encourage drivers to proceed at appropriate speeds without actually posting the speed limit. Even though drivers have the responsibility to drive at a safe speed, they need to be able to receive cues from the roadway environment as to what that safe speed is.

SECTION I—SUMMARY I-5 • Ensure roadway design and traffic control elements support appropriate and safe speeds—Geometric design features of roadway sections and intersections, and operation of traffic signals, need to reflect the speeds desired of drivers. For example, roadway design elements sensitive to the context in which they will be located can encourage appro- priate speed choices by drivers. Geometric elements which affect operating speeds, such as horizontal and vertical curves, can be designed in combinations to encourage appropriate speeds. Intersection types and designs should be appropriate for the context of the road- way. Providing a proper signal coordination through intersections along a corridor can create uniform speeds and reduce the need for drivers to stop at the intersections.

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TRB's National Cooperative Highway Research Program (NCHRP) Report 500, Vol. 23: Guidance for Implementation of the AASHTO Strategic Highway Safety Plan: A Guide for Reducing Speeding-Related Crashes provides suggested guidance on strategies that can be employed to reduce crashes involving speeding.

In 1998, the American Association of State Highway and Transportation Officials (AASHTO) approved its Strategic Highway Safety Plan, which was developed by the AASHTO Standing Committee for Highway Traffic Safety with the assistance of the Federal Highway Administration, the National Highway Traffic Safety Administration, and the Transportation Research Board Committee on Transportation Safety Management. The plan includes strategies in 22 key emphasis areas that affect highway safety. The plan's goal is to reduce the annual number of highway deaths by 5,000 to 7,000. Each of the 22 emphasis areas includes strategies and an outline of what is needed to implement each strategy.

Over the last few years the National Cooperative Highway Research Program (NCHRP) has developed a series of guides, all of which are now available, to assist state and local agencies in reducing injuries and fatalities in targeted areas. The guides correspond to the emphasis areas outlined in the AASHTO Strategic Highway Safety Plan. Each guide includes a brief introduction, a general description of the problem, the strategies/countermeasures to address the problem, and a model implementation process.

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