Earlier this month, the Metropolitan Manila Development Authority (MMDA) received flak from motorists who noticed the disappearance of countdown timers from intersection stoplights around Metro Manila. As it turned out, the government agency planned to replace the old system with one that makes use of adaptive traffic lights.

Change can be annoying, but in this case the MMDA is modernizing for the better. The agency also has been providing information for drivers to know more about the new technology it is implementing, known as the Adaptive Responsive Traffic Signal System (ARTSS).

Adaptive traffic lights VS traffic lights with countdown timers

MMDA Traffic Operations Officer V Francisco Pesino Jr. explained the adaptive system in an interview with CNN Philippines and enumerated three basic modes in which the system could operate: fully actuated, semi-actuated, and fixed time.


Adaptive Traffic Lights System

In the fully actuated mode, the right of way of vehicles at intersections are based on the actual traffic volume and flow demand. There is no fixed cycle length on the green interval, as this will be determined by the detectors or sensors in the system.

Another MMDA official, Edison Bong Nebrija, shared a video on Facebook to show an example scenario where the adaptive system would be more appropriate.

In the video, he had to wait at M.H. Del Pilar St. in Manila for more than two minutes, even though the intersecting Quirino Avenue essentially had non-existent traffic. The traffic light then only gave a fixed 15-second duration when it finally turned green, which was way too brief given the long line of vehicles waiting to turn at the time.

Fixed-Time Mode


According to Pesino, the countdown timers are only applicable under the fixed-time mode. Vehicle volume detection is disabled in fixed-time mode, which means the detectors won’t conflict with the countdown timers.

Regardless, countdown timers on traffic lights with fixed cycle lengths have their own advantages. For instance, they are best suited for closely spaced intersections, and they can be used as a temporary mode for when the sensors malfunction and cause the adaptive system to fail.

The MMDA also revealed that sixty percent (60%) of major intersections across Metro Manila have been installed with ARTSS sensors or detectors in lieu of the countdown timers. Full installation of the sensors at all intersections, which also means the complete phaseout of countdown timers, may take up to three (3) years.

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