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Delay-Volume Relations for Travel Forecasting: Based on the 1985 Highway Capacity Manual


This report discusses the 1985 Highway Capacity Manual in relation to travel forecasting models. It was found that important incompatibilities exist between the HCM and most travel forecasting models; ways of reconciling these incompatibilities are suggested.

This report suggests parameters for speed/volume functions for uncontrolled road segments. For controlled facilities, the reports suggests values for link speed and link capacity to be used prior to network calibration. These speeds and capacities depend upon the type and manner of traffic control.

The report also provides sample specifications for delay relationships that can make a travel forecasting model consistent with the HCM. Separate specifications are provided for signalized intersections, all-way stop controlled intersections, some-way stop controlled intersections, and two-lane roads.

Updated: 3/25/2014
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