Abstract
One of the primary determinants of signalized intersection delay, and consequently signalized arterial level of service, is progression quality. Progression quality is represented by an arrival-type variable in the Highway Capacity Manual (HCM) procedure for calculating signal delay. Ideally, the arrival type is estimated from collected field data, in particular the percentage of vehicles that arrive at an intersection approach while that approach has the green signal indication. The Florida Department of Transportation prescribes the use of its ARTPLAN software program for planning-level analyses of signalized arterial level of service in the state of Florida. This software is a planning-level implementation of the arterial analysis methodology contained in Chapter 15 of the 2000 HCM. One of the inputs to this software program is arrival type. Given the significant impact this variable can have on delay, and subsequently level-of-service results, it is prudent to have as good an estimate of its value as possible. However, collecting accurate data on progression quality is very difficult, and the intent behind a planning-level analysis is that detailed field data should not be required. Consequently, the blanket HCM recommendations for arrival type are often applied in these analyses without much consideration of how appropriate these values really are for the specified roadway, traffic, and control conditions. A method developed to estimate arrival-type values with a simulation-based approach from the planning-level inputs of ARTPLAN is described. Also provided is a summary of simulation-derived arrival-type values from a large number of sample data sets.
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