BRTS ‘brain’, smart traffic

One of the predominant features of the Bus Rapid Transit System (BRTS) in Ahmedabad will be the encumbrance-free operations in the dedicated bus lanes.

With a view to providing advanced engineering technology, the BRTS corridor and special intersections will be managed by a special system known as the Area Traffic Control System (ATCS).

The Ahmedabad Janmarg Ltd (AJL) has introduced this system at 93 intersections, of which 65 are along the BRTS corridor and the rest at non-BRTS intersections. In the first phase of the BRTS, 17 open intersections on the stretch from the RTO to Pirana will be controlled by the ATCS, further enhancing the efficiency of the BRTS operations.

Apart from the major intersections, all bus shelters and pedestrian crossings will have a similar signal system, to increase the safety of commuters and pedestrians.

ATCS
The model used for the operations of the Area Traffic Control System (ACTS) is simple. Each intersection is provided with loop detectors, which are installed beneath the pavement layers on each arm. These detectors will take into account the number of vehicles passing over each part of the route over a period of three seconds.

The detectors are connected with traffic controllers, which are located at the corners of the intersections. Each traffic controller is connected with the master control centre at Victoria Garden through a managed lease line of BSNL. The managed lease line will play the vital role of data collection, signal coordination and connectivity of the server.

Intersection management
The geometrics of all intersections of the BRTS route are designed based on the traffic pattern, available RoW, location of intersections in the overall road network and phase-wise execution of the BRTS project. All the intersections have traffic signals to control and manage the BRTS buses as well as the mixed traffic.

The principal aspects of the traffic signal system are an increase in mobility and reduction in delays at intersections. This is possible only if the number of phases in each signal cycle is minimised.

For the same purpose, the segregated phase of the BRTS buses in the signal cycle has been eliminated at intersections having a corridor for only two arms, i.e. at intersections where two BRTS corridor meet there will be a separate signal phase for the BRTS buses. This will ensure lesser delay for mixed traffic. For each intersection, the signal cycle length and number of phases have been designed using state-of-the-art technology.

Signal synchronisation
Signal synchronisation is defined as coordination of signals at junctions in order to reduce delays and improve the level of service for the system as a whole. Generally, such synchronisation is carried out at the main corridor of a city, where the maximum amount of traffic can pass with minimum delays.

The affecting parameter for the coordination is the average speed of vehicles on that stretch and the proportion of various vehicles. However, the green time is an important parameter at the junction to prefix efficient coordination.

While coordinating he signals on the BRTS corridors, two further factors have been taken into consideration, that traffic is moving at speed and that when the traffic is released from one junction, there must be minimum red at the next junction.

Pedestrian safety
Other special features of the BRTS signal coordination are the bus shelters and pedestrian crossings. As all bus shelters are located near the intersections, pedestrian movement at the nearby shelters and intersections will be very high. The safety of the pedestrians and reduction in delays for vehicles approaching intersections can be ensured only through coordination.

All such crossings have separate signals for pedestrians and are coordinated with the nearby signals of intersections in such a way that both have the same signal phase, i.e. red or green, which will provide continuous movement of traffic as well as ensure the safety of pedestrians.