The Bangkok Metropolitan Administration (BMA) plans to accelerate the rollout of adaptive traffic lights across the city in an effort to reduce congestion.
The initiative will see traditional fixed-time traffic signals gradually replaced with an adaptive control system. During a briefing on the programme, Deputy Governor Wisanu Subsompon said Bangkok manages 746 intersections, with more than 80% still operating under a fixed-time system that uses pre-set intervals for green and red lights.
Such a system cannot adjust to changing traffic volumes. To address this limitation, the BMA is expediting the transition to adaptive traffic control technology.
The new system uses CCTV cameras and image-processing technology to monitor traffic conditions in real time. Data collected from the cameras is sent to control cabinets equipped with advanced algorithms that automatically calculate and adjust signal timings based on current traffic flows.
Under the traditional fixed-time system, signal durations remain constant regardless of traffic levels. By contrast, the adaptive system dynamically adjusts green and red light timings in real time according to traffic volumes in each direction.
Officials say the fixed-time system is also unable to respond effectively to rush hours, emergencies or sudden changes in traffic patterns. The adaptive system addresses this by analysing traffic density and queue lengths of up to 150 metres before an intersection to determine the most efficient signal timing.
Another drawback of the current system is “lost green time”, when traffic lights remain green despite the absence of vehicles, as well as the risk of gridlock when vehicles block intersections and disrupt traffic flow.
The adaptive system includes a Grid Lock Protection feature designed to prevent such situations. If traffic ahead of an intersection cannot move, the system automatically cuts the green signal to stop more vehicles from entering and blocking the junction.
For the current fiscal year, the BMA plans to install adaptive traffic control systems at an additional 50 intersections across Bangkok.