Vehicular tunnel traffic-flow control

A description of an operational vehicular tunnel traffic-flow control system is presented. Using photoconductive cells as vehicle detectors in the Lincoln Tunnel South Tube and a fixed logic hardware controller to activate traffic signals and signs at the tunnel entrance, traffic is metered in a manner which results in less congestion. The vehicle detectors use wall-mounted high-intensity light sources aimed at a cell which is located below a hole in the tunnel roadway. The cell is hard-wire connected to the logic controller. The controller, using discrete solid-state components, determines the number of vehicles between two points in a tunnel lane; in addition the controller calculates the speed of each vehicle at both points. Using these parameters, the controller decides if the entering traffic-flow rate should be lowered. If a decrease in the rate is warranted, amber traffic signals and a sign which states "pause here-then go" is then energized. When the threat of possible congestion is alleviated, the entrance controls are automatically de-energized by the controller. A comprehensive traffic-flow control and stoppage-detection system now being implemented is also discussed. This system will employ four small-scale digital computers working in pairs at both the Holland and Lincoln Tunnels. Basic raw data will come from both induction-loop vehicle detectors and photocell vehicle detectors arranged in alternating pairs at seven points in each of the ten traffic lanes comprising the two facilities. Output will consist of control signals to entrance traffic devices, as well as alarms designed to draw the attention of facility personnel to one of nine or more television monitors per tube showing the area of a detected stoppage.