Field Evaluation of Highway Capacity Manual 2000 Analysis Procedures for Two-Lane Highways

Abstract

Highway Capacity Manual (HCM) 2000 two-lane rural highway directional, two-way, and passing-lane analysis procedures based on field data and simulation were evaluated. Detailed field data were collected from two highway sections in northern Idaho, one with and one without passing lanes. The TWOPAS simulation model was used to provide additional insights. Particular attention was given to the differences in estimates for percent time spent following (PTSF) produced by the twoway and directional analysis procedures. It was found that the two-way analysis procedure was more accurate, although both procedures produced estimates that were too high. The passing-lane analysis procedure was also evaluated, and the HCM 2000 procedure was found to be conservative in its estimates of PTSF reductions due to a passing lane.