In order to assess the potential value of bus control a computer simulation of a high frequancy urban bus service 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 regulised bus depatures from termini by making adjustments to bus layover periods, whicle 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 hyover adjustment strategies reduced the mean passenger waiting time by up to 20 percent (about 1,2 minutes), but did not effectively reduce late running. Additional use of the curtailement control had little effect on the improved waiting times bu reduced the occurance 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.