A Microcomputer Model to Estimate the Benefits of Volume Generated Auxiliary Passing Lanes on Two-Lane, Two-Way Highways

by Alan R. Kaub, Univ of South Florida, Tampa, United States,

Document Type: Proceeding Paper

Part of: Microcomputers in Transportation


Safety and operational characteristics of rural and suburban two-lane roadways can be substantially improved by the provision of adequate passing opportunity, especially as traffic volumes peak on a daily or seasonal basis. Many highway agencies have regarded the next improvement for a two-lane roadway to be a four lane cross-section, but often cannot fund such significant improvements, or local residents find them undesirable. Auxiliary passing lanes appended to the existing two-lane roadway can offer improvements with significant peak period benefits while retaining the character of the two-lane roadway. This paper presents the structure of a microcomputer program which estimates microscopic safety, delay, and running cost benefits to produce a benefit/cost ratio along with cost-effectiveness estimates to assess the construction of volume generated auxiliary passing lanes or a four lane segment on a specific roadway. The program uses default or user defined hourly volume based speed and delay models for autos and trucks with safety benefits derived from a unique Statistical Probability Conflict Opportunity/cost model to estimate the passing related safety benefits. The economic assessment model uses peak and off-peak, weekday, weekend, and monthly volume characteristics to define operational benefits and to estimate accident costs and savings. Several applications of the program operation are compared to prior economic studies which indicate the usability of the program in both two-lane and four lane applications. The program has the capability to be utilized as suburban congestion management tool by estimating the length of passing lanes or four lane section to be constructed on a segment or to produce a national or statewide listing of geometric improvements based upon a stable, repeatable procedure for balancing microscopically defined benefits and costs.

Subject Headings: Traffic management | Traffic accidents | Highway and road management | Computer models | Highways and roads | Highway engineering | Construction costs

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