Wrong signals for city traffic

The 'smart' traffic signals installed in Kolkata two years ago aren't so smart any more. The area traffic control (ATC) system malfunctions more often than it works these days, leaving motorists baffled and some roads perpetually choked.

The police blame the implementing agency, Keltron, a Kerala state PSU, while Keltron blames the never-ending roadside 'developments' that wreak havoc on the cables. Unless the agencies involved get together and identify the source of the problem, the multi-crore system will continue to fail the city.

Kolkata Police had inaugurated ATS with much fanfare in 2010 after conducting trials, which is why they are finding it difficult to explain the repeated glitches in the system.

Keltron officials insist their system is not to blame. They say that the recurrent digging and raising of pavements all across the city damages the cables, throwing the traffic signal system haywire. Keltron points out that Kolkata Municipal Corporation (KMC) has been raising pavements and erecting trident street lamps, "often causing irreparable damage to cables". "We have to change the cables almost every three months," said senior Keltron officer Pradip.

The traffic police, however, blame the Kerala PSU. "There are a lot of glitches in the system. So the project is far from over even though all 95 signal-crossings have been networked with the central processing unit. Keltron, the company entrusted with putting the system in place, has let us down," said a senior police officer, adding that the "lack of technological changes" prevents signals at several key intersections from working in sync. "We are trying our best to streamline them," said joint commissioner (traffic) Supratim Sarkar.

The signal cycle on a particular stretch depends on the feed from either the 'ground sensor loop' (sensors embedded under the road surface or pavement) or the 'virtual loop' (camera images of traffic at a particular point). These feeds are analysed by the central processing unit at traffic headquarters, based on which the computer sets the best possible signal cycle.

The ATC system required an overhaul of the entire cable network on a particular grid, which Keltron said got repeatedly damaged. Moreover, there is no uniformity as far as signals are concerned. Different companies have set up different signals. So dealing with each signal proved to be a new challenge, a Keltron official said.

ATC has three modes - automatic, manual and cycle-optimization mode. Going on manual mode not only affects the signal of a particular crossing, but has a chain effect on the traffic flow of other crossings.

Keltron officials said that the traffic police must graduate to automatic signal completely. Unless, there is an emergency, manual mode is redundant, they say. The more you change a signal manually, higher the chances of human errors. And if this continues, traffic snarls on such roads become inevitable, said an official.

The glitches force traffic to halt at every signal, just as in the pre-ATC days. "There is hardly any uninterrupted flow of traffic as we were promised. I keep getting stalled at every signal. I don't find an iota of change after this so-called 'generation change' in the signalling system," said Kallol Mukherjee, a director with a liquor manufacturing company.

The Area Traffic Control project is part of a scheme that has several components other than the signal system - a GIS-based automatic vehicle tracking system, a distress-call response system and surveillance on public places. The entire project cost is Rs 20 crore.