ATCS for effective signaling cycle

The current traffic control systems in the metro cities of India are facing problems due to randomness in the traffic density pattern throughout the day. The traffic signal timers have a fixed time period to switch traffic between different directions. Due to this, the vehicles have to often wait for a long-time span even if the traffic density is very less. Adaptive traffic is basically adjusting traffic signal timings to real-time, looking at the current flow of traffic conditions, demand, and system capacity. TrafficInfraTech speaks to a few providers of ATCS to know about the special features of their systems and the challenges in effectively implementing these for traffic management.

Ravikumar P,
Joint Director, ITNS,
Centre for Development of Advanced Computing (C-DAC)

Travel needs are increasing worldwide at rapid speed. However, the road infrastructure is unable to expand at the same pace, leading to demand–supply mismatch, particularly in urban areas. This has made the traffic engineers and planners to think loud to make the available infrastructure more efficient and effective. Very wisely, Govt. of India under the Smart City Program has given thrust to safe and speedy transport in urban area through ICTE (Information Technology, Computers, Telecommunication and Electronics) enabled infrastructure. In any city traffic network major delays occur at traffic junctions due to the signal controllers. Unfortunately, most of the currently operational traffic signal controllers in our country are not intelligent. They simply exhibit the signals without assessing the real traffic conditions. Rather, refer to a timetable programmed inside the traffic signal controller prepared based on inputs from the traffic police or statistical data collected offline that may not have any correlation with the real-world scenario, resulting unresolved queues and wasted green.

Signaling systems responding to traffic fluctuations in real-time are called ‘Adaptive’. A network of traffic junctions are generally considered under the Adaptive Traffic Control Systems (ATCS) for optimally managing signal timings and reduced number of vehicle stops and delays. Almost all the adaptive signal control systems currently operational across the globe are developed in developed countries considering the predominantly homogeneous and disciplined traffic in those countries. These solutions may not be directly applicable to the non-lane based mixed traffic flow conditions predominant on Indian roads because the parameters required to model the different scenarios are different. Therefore one has to be extremely cautious while proposing a solution for Indian roads characterized by non-lane based driving and mixed traffic flow condition. Augmenting the problem are uncontrolled side roads, parking and other public facilities near the traffic junction, lane change in the middle of the junction, power failures, communication network reliability etc. Real-time data collection to model the traffic becomes highly complex and uneconomical under these conditions.

One common myth about the ATCS is that it can solve all traffic problems. But in reality, it can only help in improving the traffic conditions i.e., increase in lane carrying capacity and travel speed, reduce delays, stops, queue, fuel consumption, emission and accident rate. Philosophy of ATCS is to divide an area into corridors of closely spaced traffic junctions having similar flow characteristics and, synchronize them dynamically based on real-time demand assessed through vehicle detectors. There are various types of vehicle detectors available commercially of the shelf. Failing to select the appropriate detector could affect the performance of the system at times. For example, most ATCS are using video based vehicle detection. They work perfectly all right under ideal conditions. But, during fog, heavy rains, low ambient light conditions they are prone to fail; thermal cameras are expensive; microwave detectors are good for road-by-road traffic clearance – not always possible to segregate independent movements. This indicates that while selecting a technology considering external parameters are also important.