Intelligent traffic signals installed at 26 intersections in the vicinity of Omandurar Estate on Anna Salai have proved ineffective owing to the sheer number of vehicles that flow through these junctions.

Unable to rationalise the signal timings based on traffic volume at the junction level, the Chennai City Traffic Police (CCTP) is contemplating a grid of traffic signals that can communicate with each other and ensure the smoothest possible flow of traffic within a particular zone.

In the existing setup, a camera-cum-digital controller installation mounted on to the traffic signal decides which direction of vehicular flow must be prioritised based on vehicle density. The camera unit determines the density by drawing eight virtual loops in all four directions. If the traffic queue covers all eight loops, the maximum amount of signal timing is allowed in that direction.

Since there is maximum density on all four directions all through the day, the system has reached saturation, said Sanjay Arora, Additional Commissioner of Police (Traffic). “There is no variable timing. Only one decision prevails most of the day. The system starts functioning during the night when it is not really required.” To overcome this problem, the CCTP is looking at deploying an area control mechanism, which would try to rationalise vehicle flow within a grid, instead of just one traffic intersection.

Apart from stretches on Anna Salai and Kamarajar Salai, other high priority zones such as Rajiv Gandhi Salai and EVR Periyar Salai are in line to get such a system.

Experts say that the total delay at any traffic signal should ideally be 10 seconds. If the delay is greater than 55 seconds, a junction redesign may be required and a delay greater than 80 seconds is usually intolerable. Signal coordination and area traffic control systems can reduce the amount of delay by rationalising vehicle flow, thereby limiting the need for grade separators.

Responding to complaints regarding malfunctioning of traffic lights in many intersections, Mr.Arora cited the citywide load-shedding, which cuts off power to the signals as well, as a major problem. “On an average, about 10 traffic signals are also down every day for maintenance work. Every three months, 1/12th of all signals in the city undergo some kind of preventive maintenance. We have also entered into a Rs.18 lakh per annum maintenance contract which stipulates that defects have to be rectified within three days.”

In case motorists notice any traffic lights which repeatedly malfunction, Mr.Arora said that complaints can be registered by calling 28521323 or sending a text message to 9003130103.