Bangkok reveals smart traffic signals reduce congestion by up to 41%

At the Bangkok City Hall (Sao Chingcha), Governor of Bangkok, Chadchart Sittipunt, chaired the 6th meeting of Bangkok’s executive officials, where one of the key highlights was the successful implementation of the adaptive traffic signal system.

The meeting revealed that the city had completed the installation and activation of intelligent traffic signal systems (Adaptive Signal Control) across 72 key intersections since March 2025. These improvements focus on major road junctions in the central areas, which have long experienced significant traffic congestion.

Notable intersections include:
• Rama 9 Road
• Din Daeng Road
• Phaya Thai Road
• Sukhumvit Road
• Ploenchit Road
• Rama I Road
• Rama IV Road
• Sathorn Road
• Silom Road
• Phahonyothin Road

The new system has led to a reduction in travel delays at these intersections by an average of 10-41%, marking an important step in using technology to address traffic congestion sustainably.

What is an Adaptive Traffic Signal System?

Currently, Bangkok has around 500 traffic intersections, most of which still use the "manual system" or "Fix Time" system. This involves setting fixed green and red light durations based on a pre-programmed schedule, or having police officers manually control the lights based on the traffic conditions they observe. However, this system has several limitations, such as:

Although countdown signals are visible, indicating fixed timing, it is common to see a clear lane on the green light side, while the red light side has a traffic jam, causing unnecessary delays and wasted resources.

Even when police officers control the signals, while they can adjust based on the situation, they cannot see the full traffic flow at the intersection, which may result in suboptimal decisions.

However, the Adaptive Signal Control system, now being used in Bangkok, works quite differently. It operates on the following principles:

• Traffic Volume Detection (Image Processing Cameras): Instead of using traditional sensors, this system uses high-precision video cameras installed at intersections. These cameras act as "eyes," continuously monitoring and processing the traffic flow in real-time for each lane.
• Intelligent Computer Processing (Central Processing Unit): The data from the cameras is sent to a computer, which uses Artificial Intelligence (AI) and Algorithms to calculate and analyse the information. The system then decides the optimal timing for the traffic lights to maximise efficiency and minimise travel delays.

Benefits of Adaptive Traffic Control

• Real-time signal adjustments: The system adjusts traffic light timings based on the actual traffic volume, extending or shortening green light durations as needed. It avoids giving green lights in directions with no traffic and works to clear congested areas as quickly as possible.
• Reduced delays: Early trials of the Adaptive Control system during non-peak hours showed a 15% improvement in traffic flow. Data collection is ongoing during peak hours in collaboration with police to accurately assess its maximum efficiency.
• Improved overall traffic efficiency: The system ensures smoother traffic flow, reducing unnecessary stops, saving travel time, cutting fuel consumption, and lowering air pollution.

Expansion Plans and Traffic Discipline Reminder

Currently, Bangkok has installed and activated the Adaptive Control system at 72 key intersections along major roads such as Sukhumvit, Phetchaburi, Rama IV, Phahonyothin, and Silom. These areas are heavily congested, with plans to add another 200 intersections next year, aiming for comprehensive coverage across Bangkok.

However, Chadchart emphasised that while technology is advanced, the most crucial factor is "traffic discipline" from all road users.

If people fail to follow traffic rules, ignore traffic signals, or lack driving discipline, no technology can fully resolve the problem. In some intersections with severe congestion, coordination between the intelligent system and police control may still be necessary for proper management of specific situations.

The combination of smart technology and public discipline will be key to transforming Bangkok's traffic for the better in the future.