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27 4. Consider additional tried treatments. For treatments for safety improvements on rural two-lane highways. IHSDM which reliable effectiveness measures cannot be estimated, will likely be expanded in the future to address facility types apply Procedure 3 to select additional treatment types and in addition to rural two-lane highways. target locations or subpopulations, until all available The forthcoming Highway Safety Manual (HSM), sched- funds have been budgeted. uled for publication in 2008, will present formal procedures for estimating the crash/injury reduction effectiveness of specific improvement types, including an expanded set of Other Safety Analysis Tools CRFs and AMFs representing countermeasure effectiveness. The procedures presented above supply a goal-oriented In the meantime, an expanded set of AMFs developed in approach to developing plans for safety improvement NCHRP Project 17-25 has been presented in NCHRP programs. Users should be aware of other analytical tools that Research Results Digest 299 (27). are being developed to assist in this process. FHWA's Safety- Analyst software, planned for release in 2006 or beyond, is Summary intended for application to safety management of a highway system, but may be an effective tool for safety planning as The procedures presented above have defined the overall well. Key capabilities of SafetyAnalyst include: process for planning safety improvements in any specific emphasis area. At this point, it is assumed that the user will Screening a highway network to identify sites with poten- have completed Stage 1 (i.e., define/choose the issue to be tial for safety improvement. addressed) and Stage 2 (i.e., setting a stretch goal) using the Diagnosing selected locations to identify collision patterns. guidance provided earlier and guidance provided in other Selecting of countermeasures potentially applicable to the documents such as NCHRP Report 501. The following identified collision patterns. sections of this manual will provide more detail on how to Using economic analysis tools to perform cost-effectiveness conduct the final step treatment selection and targeting and benefit-cost analyses. These economic analysis tools for each of the 22 emphasis areas in the AASHTO Strategic will include an optimization routine to select a mix of Highway Safety Plan, or for groups of emphasis areas for improvement locations and countermeasures that maxi- which the data needed and the procedures to be applied are mizes the total safety benefits from a given budget for safety similar. Subsequent sections provide guidance on how to improvement. proceed with the planning process when relatively complete Priority ranking potential safety improvements based on data are available, and when only limited data are available. economic analysis results. It is again noted that a jurisdiction's full safety plan should Evaluating the effectiveness of countermeasures after they include multiple issues/emphasis areas (e.g., run-off-road are implemented. crashes, crashes involving heavy trucks, and crashes involv- ing drinking and driving). Stage 1 will have defined the full SafetyAnalyst is location-oriented and budget-oriented, un- set of issues/areas to be addressed, and Stage 2 will have like the procedures presented above which are goal-oriented. defined goals for each issue. The user can then use the More information is available at information provided in each of the individual sections FHWA's Interactive Highway Safety Design Model below to conduct Stage 3 treatment choice and targeting (IHSDM) may assist in the design and analysis of candidate for each of the issues in the full plan.