A Microcomputer Package for Interrelating the Highway Capacity Manual and SOAP 84

by Dane Ismart, Federal Highway Administration, United States,
Ronald Giguere, Federal Highway Administration, United States,



Document Type: Proceeding Paper

Part of: Microcomputer Applications in Transportation III

Abstract:

There is some evidence that the SOAP program may replicate signalized intersection delay more realistically than the 1985 Highway Capacity Manual (HCM) operational procedure for signalized intersection. The major drawback to SOAP is that the user must specify the saturation flow rates and through movements in all the approaches. This paper describes a procedure that will transform the saturation flow calculations from the Highway Capacity Manual into values that can be used in SOAP 84. The general approach taken is to convert left turns into equivalent through movements. Then, a comparison is made between the left turn equivalent movements and the actual through movements in the lane. The ratio between equivalent left turn through movements and actual through movements should be similar to the ratio between left turn satruation flow and through movement saturation flow for the shared lane. Using these principles, procedures necessary to calculate saturation flow for shared left through lanes are given.

Subject Headings: Traffic capacity | Traffic signals | Traffic flow | Traffic delay | Computer software | Intersections | Left turns

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