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1 SUMMARY Safety Data and Analysis in Developing Emphasis Area Plans In 1996, the American Association of State Highway and Transportation Officials (AASHTO), along with the Federal Highway Administration (FHWA), the National High- way Traffic Safety Administration (NHTSA), and the Transportation Research Board (TRB), convened a meeting of safety experts and highway safety stakeholders to develop a comprehensive Strategic Highway Safety Plan (SHSP). The plan developed by the team focused not only on engineering strategies for roadway improvement, but also incorporated education, enforcement and emergency response in order to reduce injuries and fatalities on the highways. The committee identified 22 emphasis areas in these 6 categories: Drivers, Vehicles, Special Users, Highways, Emergency Medical Services and Management. In 2003, AASHTO's Board of Directors, the U.S. Department of Transportation, the Governor's Highway Safety Association and the American Association of Motor Vehicle Administrators set a goal to reduce annual highway fatalities by 5,000 to 7,000 by 2008. In order to meet this goal and help state and local jurisdictions implement the Strategic Highway Safety Plan, a series of implementation guides were developed under NCHRP Project 17-18(3), each focusing on one of the 22 emphasis areas outlined in the SHSP. To date, 20 implementation guides have been published as individual volumes in the NCHRP Report 500 series, addressing drivers, vehicles, special users, highways, and emer- gency medical services. Each guide provides users with helpful information about proven, tried and experimental countermeasures to address the objectives relative to that specific emphasis area. The guides encourage finding appropriate combinations of strategies from all of the guides to best address the specific safety concerns in each individual jurisdiction. This requires the coordination of efforts by all stakeholders, including enforcement and judicial officials, school and community educators, engineers and planners and emergency responders. However, guidance in how to develop this synergy has been limited. The basic principal in developing an effective safety plan is to achieve the greatest results with the least cost, or, in other words, to identify the strategies and countermeasures with the greatest benefit-cost (B/C) ratio for each safety concern (whether it be location, user group, vehicle type or crash type), and the combination of strategies that provide the best B/C ratio across the entire system. In order to determine what these ratios are, data about crashes and the vehicles and people involved in them, as well as data associated with the effectiveness and costs of each countermeasure must be collected, organized, linked and analyzed. In many cases, the available data will be limited or unknown. While police crash records are the most basic form of roadway safety data which can be made available to analysts in any jurisdiction, the information recorded on the report may vary from location to location, as different forms are used in different places. The crash location can be reported with varying levels of specificity, as well. Other data sources, such as hospital and other medical records, insurance records, and licensing information, may or may not be available and may or may

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2 not be linked to crash data. Roadway inventory information in some jurisdictions is detailed and linked to crash records, while in others the information is limited and may be difficult to link to crash data. Also, for many of the strategies suggested in the implementation guides, there have been no valid studies which provide expected crash reduction factors. Therefore, it is up to the user to use the information provided about the strategy to estimate how effective he or she believes it will be in the jurisdiction's specific application of it. Because each juris- diction is likely to have access to different types of data, and no jurisdiction will have perfect and complete data, determining the best set of strategies to include in a safety plan can be over- whelming for any highway safety official. Description of the Data and Analysis Guide This guide specifically addresses highway safety data, an emphasis area under the Manage- ment category in AASHTO's SHSP, and was developed to aid highway safety analysts in using the other implementation guides to make decisions about how to appropriately allocate safety funds to get the best results. Section I introduces a three-stage process for identifying a target emphasis area, setting an appropriate injury (and fatality) reduction goal, and defining the treatments that will allow the jurisdiction to reach that goal. Section II steps the user through the types of data that are necessary for making good safety decisions, as well as the data that are helpful, but not required, to develop and implement a safety plan. Information regarding several national sources of data, as well as suggestions about how to obtain and organize local data, is also included in this section. Section III lays out the details of the three-stage process introduced in Section I, and dis- cusses the four procedures that may be used to follow the process. Each procedure is specific to the available combination of data a jurisdiction has for crash data, non-crash data, and strategy effectiveness. The remaining sections provide a detailed description of the specific application of the three-stage process and appropriate procedures for roadway segments (Section IV), junc- tions (Section V), special road users (Section VI), illegal driver actions (Section VII), unsafe driver actions (Section VIII), special vehicles (Section IX), work zones (Section X) and EMS services (Section XI). Finally, Section XII describes how data improvements can improve a jurisdiction's ability to most appropriately use their safety funding to implement the best combination of strategies to reduce the greatest number of injuries and fatalities. How to Use This Guide We recommend that users become familiar with the other implementation guides in this series (especially those that address emphasis areas that are safety concerns in their jurisdic- tions) and the objectives and countermeasures detailed in them before attempting to follow the three-step process outlined in this "Data and Analysis Guide." However, Section II and Section XII are appropriate to consult in the beginning stages of the development of a safety plan. Section II outlines types of data that are required and helpful in understanding specific safety concerns and needs and also provides resources for national crash and non-crash data. Section XII discusses ways to improve crash and non-crash safety databases to allow the user to make more beneficial decisions regarding choice of strategies and allocation of funds. Users may want to make some of these data collection and management suggestions long- term goals within their highway safety plans. Once users have an understanding of the accessibility, limits, and needs of their own data systems and are familiar with the other guides in this series, they can follow the process

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3 introduced in Section I and detailed in Section III to begin defining injury reduction goals and identifying the strategies that will help to reach those goals in each relevant emphasis area. They can then choose which procedure is most tailored to the data that is available to follow the three-step process. The procedures address these data scenarios: Procedure 1: Treatment effectiveness is known, and both crash and non-crash (e.g., roadway inventory and traffic) data are available. Procedure 2: Treatment effectiveness is known and crash data are available, but detailed inventory is not available. Crashes are mileposted Crashes are not mileposted Procedure 3: Treatment effectiveness in terms of crash/injury reduction is not known. Procedure 4: Treatment effectiveness in terms of crash/injury reduction is known for some strategies under consideration, but not for others. Procedures 1 and 2 allow the user to develop B/C ratios, which gives the most informa- tion about how far safety dollars will go to save lives and prevent injuries. B/C ratios cannot be developed in Procedure 3, because information is not known about the expected effec- tiveness of the strategies. Safety decision-makers must use other means, much more dependent on judgment, to rank strategies, and will have to make assumptions about how close those strategies will get them toward reaching their crash/injury reduction goals. Procedure 4 is a combination of the other strategies. Note that depending on the emphasis area being considered (as they are considered one at a time within this process), the same procedure may not always be used. For example, when addressing intersection crashes, the available data may allow you to use Procedure 1, but when addressing crashes involving bicyclists, you may have to use Procedure 3. Once the user understands the procedures used to follow the three-step process, he or she can then choose an emphasis area and go to the specific section that addresses it (Sections IV through XI) to follow the detailed procedure outlined for that emphasis area. This process can be repeated for each of the emphasis areas that are to be addressed. Other Helpful Resources NCHRP Report 500, Volumes 120 As mentioned above, these implementation guides detail strategies and countermeasures to address safety concerns in several of the 22 emphasis areas outlined in AASHTO's Strate- gic Highway Safety Plan. Crash reduction factors (CRFs) and accident modification factors (AMFs) are provided for several of the strategies discussed. This information is required to determine the B/C ratio for the strategy you are considering. Research is continually pro- gressing to develop the AMFs or CRFs for more strategies, as well as refining or confirming the factors already in use. It is recommended that users of this series continue to check the literature for new research in these areas. NCHRP Report 501: Integrated Safety Management Process This report addresses "Creating More Effective Processes and Safety Management Systems," which is one of AASHTO's 22 emphasis areas, and, coupled with this "Data and Analysis Guide," covers the emphasis areas under the Management category of the SHSP. NCHRP Report 501 develops a six-step process for bringing together all highway safety stakeholders and

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4 developing and implementing a comprehensive highway safety program. The "Data and Analysis Guide" supplements this process by providing detailed instruction on how to use the available data to make the decisions required in developing a safety plan. AASHTO Strategic Highway Safety Plan For background information, and to read the plan on which these implementation guides are based, visit: http://safety.transportation.org/doc/Safety-StrategicHighwaySafetyPlan.pdf.