The findings are presented of an investigation to determine the influence of including or excluding terminal times in the development of travel time factors (friction factors) for a gravity model traffic analysis for a small urban area. This investigation was made by developing travel time factors for the urban area of rock hill, s.c. using two procedures. The first procedure developed the factors using only over-the-road driving time as a measure of spatial separation. The second used total travel time (over-the-road driving time plus terminal time) as a measure of spatial separation. Internal auto driver trips for purpose of home- based work, home-based non-work, and non-home-based and truck trips were included in the analysis. Separate assignments to the street network were made of the trips reported in the home interview and the trips developed by the two gravity models. Statistical tests comparing the assigned link volumes and CBD zonal interchanges indicated that both gravity models reproduced adequately the trip distribution patterns of the home interview data. The travel time factors developed using both driving time and terminal times were found not to differ significantly from those using only driving time, except in the case of non-home- based trips. it was concluded that while there were basic differences requiring further investigation the gravity model provided an adequate framework for determining trip distribution patterns using either the model with terminal times or the model without terminal times. /author/.
Samenvatting