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16 SECTION III Details of the Three-Stage Process This section will further define the three-stage process for Safety Management Process (18), which provides details of developing an emphasis-area plan introduced in Section I. It more than one type of problem-identification procedure in is again noted that the AASHTO Strategic Highway Safety Section D1.3 of Appendix D. The focus of this guide is on the Plan intends that multiple issues should be addressed and development of safety improvement plans for each emphasis multiple plans developed. Much of the emphasis in this guide area once the allocation of funds between emphasis areas has is on Stage 3 procedures choosing treatment strategies and been determined. However, these processes can be performed targeting them. This is because procedures for choosing in iterative fashion. Once the safety improvement plans for emphasis areas of interest and setting the injury and death- individual emphasis areas have been developed, it may be reduction goals are covered in NCHRP Report 501 in detail. desirable to revisit the allocation of funds between emphasis However, an overview of all three stages will be presented areas and increase or decrease the funding for specific empha- here. sis areas as appropriate. As described in detail there, the analyst will generally first perform multiple data runs of perhaps each variable in the Stage 1 Define/Choose One or More crash data (e.g., driver age, crash type) to determine which of Issues/Emphasis Areas the data codes within each variable show high frequencies of As noted above, the safety planning team will first need to crashes. Since some crashes are more severe than others, define or choose an issue (emphasis area) or set of issues that crash severity as well as frequency should be considered in need to be addressed. There is a large array of safety problems choosing the emphasis areas. As detailed below in Section III, that could be treated in any jurisdiction. Thus, at first glance, Stage 3 of this guide, one method of combining both the possible issues are boundless. However, it should be noted frequency and severity is through weighting each crash in that extensive analytical effort was conducted in the develop- each crash type by an economic cost based on its severity. In- ment of AASHTO's Strategic Highway Safety Plan to identify formation on economic cost per crash by severity level for 22 critical safety issues/emphasis areas. In addition, extensive 22 different crash types categorized by speed limit category efforts have been made to identify the best possible low-cost can be found in Crash Cost Estimates by Maximum Police- but effective treatment strategies for use in these 22 areas, Reported Injury Severity Within Selected Crash Geometries (22). thus making the development of a jurisdiction-specific safety The use of crash costs rather than just crash frequency will program much easier. While not always the case, the same provide the analyst with overall information on which crash critical problems would most likely exist in any jurisdiction. types are most important in his/her jurisdiction. Analysts So "defining" here is usually related to determining which of who do not wish to assign explicit costs to individual crash the 22 identified emphasis areas are most critical in your severity levels can use an alternative cost-effectiveness jurisdiction. approach using weights for specific severity levels to generate The choice of emphasis area(s) is usually done with some equivalent property-damage-only crash frequencies. This type of "problem identification" analysis of crash and other approach is analogous to using estimates of crash costs by safety-related data. This is a critical part of the safety planning severity level, except in this case the severity-based crash costs process, but the presentation of detailed procedures for con- are replaced by severity-based weights. ducting such analyses is outside the scope of this guide. Both frequency and severity-based crash costs provide Instead, the user is referred to NCHRP Report 501: Integrated initial information based on most important crash types