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6 are potentially useful in safety plan development, as a supple- Note that the AASHTO Strategic Highway Safety Plan and all ment to crash data or when crash data are not available. of the supporting resources (e.g., NCHRP Report 501) intend This guide addresses the development of safety plans for that multiple issues should be addressed and multiple plans specific emphasis areas, but does not address the evaluation of developed. The guide deals with addressing one issue at a the effectiveness of those plans after their implementation. For time, but the procedures will be applied multiple times to evaluation issues, the reader is referred to NCHRP Report 501 address all issues of interest. As described later, the choice will (18) and to specific safety evaluation tools such as SafetyAnalyst. most often be based on analysis or crash data which assist the The goals of this guide are the following. user in determining which of the 22 issues/areas defined by AASHTO or additional jurisdiction-specific issues are most · Specify a basic three-stage procedure to be used in develop- critical in his or her jurisdiction. ing an emphasis area plan: (1) choosing an area, (2) setting a goal, and (3) choosing among potential strategies within the Stage 2. Set a Crash, Injury or Death Reduction given area and targeting their implementation to subpopula- Goal for That Issue tions of road users, vehicle types, or roadway locations. · Define data-related procedures for roadway, road user, and The emphasis-area team will then use a series of factors to vehicle-based emphasis areas that will assist the user in the define a reduction goal for death and injuries in each of the third stage choosing among potential treatment strate- emphasis areas chosen. AASHTO has suggested that a gies and targeting the strategies. "stretch goal" be established for both the overall safety · Define procedures which can be used with three levels of program composed on a combination of emphasis areas, and safety data and treatment effectiveness: within a given emphasis area. This "stretch goal" is one that Known treatment effectiveness combined with linkable is not likely to be met by existing safety efforts, or even a crash, roadway inventory and traffic data limited expansion of these efforts. The goal will push the Known treatment effectiveness and crash data only jurisdiction to be innovative in defining new programs and (e.g., no inventory data) procedures to achieve success. The agency may decide to Unknown treatment effectiveness and crash data only define both a "stretch goal" and a series of reduced or lesser · Customize the procedures and data descriptions for differ- goals that can be met either within a given time period or with ent groups of emphasis areas (e.g., lane departure crashes, innovative, but realistic, efforts. special road-user populations including older and younger drivers, pedestrians and bicyclists). Stage 3. Define the Series of Treatments and the Target Subpopulation (Drivers, Highway Corridors, The following text will provide an overview of the proposed Intersections) for Each Treatment That Will Be data analysis procedures to be covered in this guide. Descrip- Required to Meet Your Goal tions of potential safety data files for use in these and other procedures will be presented in Section II of the guide. General The goal of this step is to develop a combination of treat- details of the procedures will be presented in Section III. The ment strategies and targets which will allow the user to meet procedures will then be customized for specific groups of the established goal. In general, this will require the following emphasis areas in Sections IVXI. Finally, information on steps. improving existing databases will be presented in Section XII. 1. Define possible subpopulations (e.g., drivers, miles of spe- cific highway types, intersection types in specific highway Introduction to Proposed Procedures classes) for treatment. As indicated above, the development of a safety- 2. Specify one or more proposed treatments for each target improvement plan is a multi-stage process. (For clarity, the subpopulation. term "stage" will be used to describe the major procedures re- 3. If treatment effectiveness is known, determine if the num- quired to develop the plan. The term "step" will then be used to ber of targets (e.g., miles/drivers/intersections) that can be describe individual steps/processes required to conduct a given treated in each subpopulation will lead to reductions that major stage/procedure. Thus, there are "steps" within "stages.") meet the specified goal. If not, add additional treatments or new target populations (e.g., local roads if the original targets were on the state system). Stage 1. Define/Choose Issue(s)/Emphasis Areas 4. If possible, determine whether the benefits derived from The safety planning team will first define or choose an issue treating the target subpopulations exceed the costs. (Note (emphasis area) or set of issues that need to be addressed. that this assurance that the treatment is cost beneficial does
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7 not have to be a separate step. With processes presented public information campaign onto scheduled enforce- later in this guide, it can be done during the definition of ment activities). target subpopulations if "full data" are available and if 6. If cost-effective, implement the treatment(s)! treatment effectiveness is known. This benefit-cost calcu- lation will not be possible for treatments without defined Note that all these steps may have to be done interactively effectiveness levels.) until a final solution is reached. In addition, they may not be 5. If a treatment for a specific subpopulation is not cost- done in the sequence shown here. For example, as noted effective, consider other possible treatments with higher above, the final definition of target subpopulations may be crash-reduction potential, consider alternative targets done before the determination of strategies, and may also be (e.g., local road systems if you are a state DOT), or done concurrently with the determination of B/C ratios, consider ways to reduce the cost of the treatment imple- depending on the methodology used. The following sections mentation (e.g., combine roadway safety treatment with will provide more specific guidance concerning this overall other non-safety work at chosen locations, piggy-back procedure tailored to the different types of emphasis areas.