The 'Queensway' Mersey Tunnel Entrance Control Project

In 1968, A computer-controlled system was installed by the City of Liverpool to schedule vehicles on the approaches to the "Queensway" Mersey tunnel. In 1972, the scheme was extended by their own Engineering Division, to provide direct control of the traffic entering the tunnel itself. This paper discusses the project, together with some of the problems encountered in the design of the scheme. Flow measurements have shown an overall increase of about 5 percent, in hourly flows. The success of the scheme is reflected by its smooth operation, even at the peak of commuter flow. A considerable reduction in vehicle breakdowns within the tunnel has been experienced. Air pollution inside the tunnel caused by vehicle exhausts in much less when fluid conditions are maintained, and the fact that traffic is delayed less on the approaches infers that external pollution is also reduced. Additional traffic-sensitivity has been introduced into the computer program to enable the system to react more rapidly to changing conditions, and in the near future, it is hoped to predict approach delays by sampling the flow throughout the tunnel.