Improving the Running Times in Highway Capacity Manual Table 11-4;Related Observations on Average Travel Speed

Abstract

An arterial planning methodology has been in use in Florida for several years and influences decisions in developments of regional impact and other analyses. It is incorporated into the Florida Level of Service Manual. Experience has indicated that analysts using the default values are concerned that the average travel speeds are underestimated by 10 km/h or more. Given the known limits of the data underlying the arterial running time and running speed default estimates in the Highway Capacity Manual (HCM), it was decided to conduct an extensive simulation analysis using a well-established model (NETSIM, now part of CORSIM). The findings are that (a) simulation-derived running speed estimates are at least some 10 km/h higher than the HCM default values, (b) moreover, the running speed estimates generally do not decrease as sharply as the HCM default values as signal density increases, and (c) unlike the HCM default values, the simulation-derived estimates are sensitive to increased demand volume. In addition, the derived values clearly reflect the through vehicles, consistent with the original HCM intent.

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