Bus TRANSYT is a computer program which calculates traffic signal timings that give buses priority in a network of linked fixed-time signals. Buses are modelled separately from other traffic; they follow fixed routes through the network and stop at bus stops. allowance is made for the variation in running speeds and in the stopped time at bus stops. buses are given priority by weighting their delay more than the delay to other vehicles when the signal timings are optimised. Approximately two-thirds of the bus benefit comes from optimising the offsets and one-third from optimising the green durations. The program is insensitive to errors in the data on bus speeds and stopped time at bus stops. for a full scale test in Glasgow's 95 intersection network, bus speeds were estimated from 1 man-day's observations and the stopped times at all the bus stops were estimated by surveying a sample of 21 stops. the test showed an 8 per cent increase in bus journey speeds over the working day. Delay to other vehicles on bus routes was reduced by 5 per cent but delay off bus routes was increased by 10-20 per cent. Overall delay to other vehicles showed no significant change. (Author/publisher)
Abstract