In order to assess the potential value of bus control a computer simulation of a high frequency urban bus service (London transport service 11) has been used to estimate the likely effects of applying a number of control strategies formulated for use when the positions of buses on the route were known. Four strategies were considered: the first three regularised bus departures from termini by making adjustments to bus layover periods, while the fourth curtailed buses short of their scheduled destinations in order to make up lost time. Initially these strategies were evaluated with levels of cancellations (16 per cent) and unpunctuality at the start of the day which were typical of service 11 at the time of the study (1975). Combined use of the layover adjustment strategies reduced the mean passenger waiting time by up to 20 per cent (about 1.2 minutes), but did not effectively reduce late running. Additional use of the curtailment control had little effect on the improved waiting times but reduced the occurrence of bus lateness in excess of 10 minutes by a factor of about two. These benefits were shown to be sensitive to both the level of cancellations and the degree of poor time-keeping on starting. When all the buses started on time the magnitude of the waiting time reduction attributable to control was reduced by a factor of about 4. (Author/publisher)
Samenvatting