Office of Planning, Environment, & Realty (HEP)
In order to better understand the implications of the HCM delay procedures for travel forecasting, a set of sample specifications was developed. Separate specifications were written and programmed for delay at signalized intersections, all-way stop intersections, and some-way stop intersections. These specifications were directly incorporated into a travel forecasting model. An attempt was made to stay as close as possible to HCM procedures while providing routines that could successfully be interfaced with the travel forecasting model. Parts of HCM procedures that appeared to have little effect on delay were abridged. Otherwise, the specifications follow the HCM quite closely.
The specifications are used later in this report (1) to develop delay/volume relationships for forecasting models that cannot be modified, (2) to demonstrate the feasibility of directly incorporating HCM procedures into a travel forecasting model, and (3) to suggest values for link capacity and free speed to be used prior to network calibration.
The sample specifications are fully described in Appendix A.