Smart signals set to ease traffic in city

Smart signals set to ease traffic in city
The city will soon have sensor-activated signals that will adjust timing depending on volume of traffic. B S Manu Rao reports


The city's traffic condition will see some improvement with more efficient signals soon. As part of the B-Trac project, all the 179 signals in the city are to be connected to the Traffic Management Centre by August 15. Already, 120 have been connected through optical fibre cables.
As part of the second phase of the project, 20 new signals will be commissioned every month in the outskirts of the city. All these will be solar powered. It is estimated that around 204 signals will be required in all in the outskirts. Of these 40 are already in place.
Finally, in the third phase, 500 'T' junctions in the city will have blinkers to warn motorists of traffic ahead. These are junctions that do not warrant a signal. All the three phases of the B-Trac project are expected to be completed by March 2009.
Vehicle actuation
Traditionally, the city's signals have had fixed timings. This was regardless of the volume of traffic passing through. Often, this led to a situation where a stretch with no traffic would have a green signal on for much longer than needed, while a connected stretch with heavier traffic will have a number of vehicles waiting unnecessarily. This led to considerable time and fuel being wasted.
In the next stage, the traffic police introduced signals with different timings depending on the traffic volume at a given point. This, while being more flexible, had its limitations too.
Now, from August 15, the vehicle actuation system will come into effect all over the city. This is a dynamic system where the green signal lasts for a minimum of nine seconds. Subsequently, four seconds are added on if vehicles are still passing through the green signal. If no vehicles pass through the signal for four seconds, it turns red allowing the next signal in the junction to turn green. This timing is maintained using sensors. Effectively, in a cycle of signals across a junction, more green time is given to stretches where the traffic volume is heavier. Green signal durations can extend upto a maximum of 80 seconds if the volume is heavy enough.
In this system, green signal times vary depending on need. Therefore, the waiting time is reduced. Through the course of a day, a considerable amount of time and fuel will be saved. It will speed up the traffic through the city and make commuting that much easier. So far, this system has been activated at 80 signals out of the 179 in the city.
This system works best in offpeak hours. If there is bumper-tobumper traffic, nothing can be done and signals will have to follow fixed times.
The logic behind this system is to keep traffic moving in small packets. This speeds up the traffic along the city's busy roads. It is seen as a more scientific alternative to switching off signals and 'pulling' traffic through busy intersections during peak hours.
Stand alone signals
The traffic police have also identified 'corridors' across the city where traffic flows in logical sequence heading from clusters to clusters. Here, stand alone signals will have an area traffic controller. These signals, connected to each other in the corridor, sense traffic volumes and adjust the green signal timing according to need. This keeps the traffic flow faster, adjusting the green timing according to need. This system is expected to be ready across the city in a year's time.
However, this system will need to be switched off for manual intervention and guidance in case of obstructions such as a fallen tree etc.
Standard signage
In yet another dimension to the B-Trac project, the traffic police are standardising traffic signage across the city. These new signage will have common features such as height from ground, colour, position and dimensions. Around 10,000 new ones are being put up over the next two months. Around 30,000 in all will be up by December this year.