THE DEPARTMENT OF MOTOR TRANSPORT (DMT) TRAFFIC SIGNAL SYSTEM IN THE NEWTOWN/ST PETERS AREA WAS USED IN A COMPARISON OF THREE METHODS OF TRAFFIC SIGNAL CONTROL: DMT-STRATEGIC CONTROL, OPTIMISED FIXED-TIME, AND ISOLATED OPERATION. THE DMT-STRATEGIC CONTROL IS A VEHICLE RESPONSIVE SYSTEM WHICH CALCULATES CYCLE LENGTH, PHASE SPLITS AND OFF-SETS IN REAL-TIME IN RESPONSE TO MEASURED DEMAND. THE OPTIMISED FIXED-TIME SYSTEM USED HISTORICAL DATA AS INPUT TO THE GREATER LONDON COUNCIL (GLC) COMBINATION PROGRAM; FOUR FIXED-TIME PLANS WERE PREPARED. FOR THE ISOLATED OPERATION METHOD, THE COMPUTER DID NOT SEND CO-ORDINATING PULSES SO THAT LOCAL CONTROLLERS RESPONDED TO LOCAL DEMAND ONLY. THE RESULTS OBTAINED SHOWED THAT IN PEAK HOURS DMT-STRATEGIC CONTROL GAVE A 35-39 PER CENT IMPROVEMENT IN JOURNEY TIME, FOR VEHICLES ON THE MAIN THROUGH ROUTE OVER OPTIMISED FIXED-TIME CONTROL. IN THE EARLY MORNING AND LATE EVENING PERIODS DMT-STRATEGIC CONTROL GAVE 24 PER CENT AND 35 PER CENT STATISTICALLY SIGNIFICANT IMPROVEMENTS RESPECTIVELY OVER OPTIMISED FIXED-TIME CONTROL. DURING THE BUSINESS HOURS NO STATISTICALLY SIGNIFICANT DIFFERENCE IN AVERAGE JOURNEY TIME WAS FOUND BETWEEN THESE TWO METHODS OF CONTROL. THESE IMPROVEMENTS WERE ACHIEVED ALONG WITH OVERALL IMPROVEMENT IN SIDE STREET DELAY AND TRAVEL TIME OF VEHICLES ENTERING AND CROSSING THE SYSTEM. ANALYSIS OF BUS-PASSENGER MOVEMENT WITHIN THE SYSTEM SHOWED THAT NO BUS PROGRESSION WAS OBTAINED WITH EITHER DMT-STRATEGIC CONTROL OR OPTIMISED FIXED-TIME CONTROL. FURTHER, IT WAS FOUND THAT THE BUS PRIORITY SCHEME INCORPORATED IN DMT-STRATEGIC CONTROL, AT A LOCALISED AREA, WAS EFFECTIVE AND GAVE IMPROVEMENTS IN AVERAGE JOURNEY TIME OF UP TO 26 PER CENT. (A). FOR THE COVERING ABSTRACT OF THE CONFERENCE PROCEEDINGS SEE IRRD ABSTRACT NO 226354.
Abstract