Indian Institute of Science

IISc scientists propose a method where lanes with more vehicles get a longer green signal on a busy city junctionWaiting at the traffic signals can be painful. Often, we wonder why the lanes with maximum traffic are not given the green signal at the earliest. Till now, much research has been done but not effectively implemented. Now, a group of scientists from the(IISc) has come out with a model based on sensors that help reduce the traffic problems in the city.The new rule is simple: The lane with maximum vehicles will get the green signal first. Of course, this idea may have been there all along; but teaching the signal lights to do this on their own, without any human intervention is a technical challenge. The number of vehicles is increasing exponentially, while the space available for them, the width of the road, has remained more or less the same. According to the Road Transport Year Book (2007-2009), prepared by the Ministry of Road Transport and Highways, Government of India, about 96 lakh vehicles were added to the Indian streets between 2008 and 2009. As a result, the time that a person would wish to spend with family or in the office is now being frittered away at the chaos on the road.Prabuchandran, Hemanth Kumar and Prof Shalabh Bhatnagar from IIsc, Bengaluru, have been working on smart ways to manage traffic signals better.Their idea aims to intelligently control traffic lights at junctions for minimising the average delay experienced by road users. The objective is to pick the most congested lane, give it the green signal first and clear the overall congestion quicker.There are two approaches to manage a busy junction. In one approach, the green signal is given in an order, but the signal duration is varied. In the other approach, the green-signal duration is fixed, but the order in which the signal is given is varied depending on the traffic volume. For example, the lane with more cars will get a green signal earlier than a less-crowded lane; but green lights up for a fixed number of seconds. IISc researchers have taken the second approach.The traffic congestion level across various lanes is available from sensors. Instead of controlling the complete road network as a single entity, each traffic junction is considered as a point of decision-making. By doing so, this approach can be used for any road network. The initial order at a junction is set randomly. At every junction, the priority of the lanes is determined based on the traffic congestion level information on the lanes on its junction and its neighbours. Based on this, high-traffic lanes are given more opportunities to stay green while low-traffic lanes are skipped from getting a green signal.This way the various junctions organise themselves by talking to their neighbours.