This report presents the findings of a research project to develop an improved cost-effective analysis procedure for assessing roadside safety improvements. The project objective has been accomplished with the development of the Roadside Safety Analysis Program (RSAP). The report will be of particular interest to roadside safety engineers with responsibility for evaluating the impacts of roadside safety improvements. RSAP is based on the encroachment probability approach and incorporates two integrated programs: the Main Analysis Program, which contains the cost-effectiveness procedure and algorithms; and the User Interface Program, which provides a user-friendly environment for data input and review of program results. The cost-effectiveness procedure incorporated into RSAP is based on the concept of incremental benefit-cost analysis. The encroachment model uses roadway and traffic information to estimate the expected encroachment frequency along a highway segment. This report describes the inner workings of the cost-effective analysis procedure and the various algorithms and data sources built into the procedure. A separate User's Manual describing the User Interface Program (including the data input process and the program reports) and the RSAP software are on CRP-CD-33, which is included with this report. (Author/publisher) For the accompanying CD-ROM `Roadside Safety Analysis Program (RSAP)', see C 30209 S CD-ROM. This report may be accessed by Internet users at http://gulliver.trb.org/publications/nchrp/nchrp_rpt_492.pdf
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