TRIP TIME CHARACTERISTICS OF JOURNEYS TO AND FROM WORK

Trip-time data on 25 routes of various distances have been collected during a period of 20 months for automobile trips to and from a common suburban work location in the Detroit, Michigan Area. Statistical analyses have been made with these data, and the results concerning trip-time charactertics on individual routes, as well as on routes in general, are presented. The total amount of stop time spent on each trip has been measured for two routes involving mainly arterial streets. When the stop time was compared to the running time of the same trip, it was found that the stop time for all practical purposes varied linearly with the running time as well as with the total trip time. Similar results have been obtained with two sets of previously reported data from Berkeley and Fresno, California. The slopes and intercepts obtained from the linear fits of stop time versus running time are reasonably consistent for the different data sets. Since the intercept is an estimate of the minimum running time and the slope is the ratio between the incremental running time and incremental stop time, the linear fit of stop time versus running time or trip time, hence, may be used to characterize a route and the traffic on it. For trips starting within consistent half hour periods, the coefficient of variation of trip times on a given route and in a given direction of travel, to work or from work, was found in most cases to be less than 20 percent. The coefficient of variation was observed, in general, to decrease with the mean trip time for trips up to 30 minutes and to be roughly constant for longer mean trip times. /Author/