VAC Signals: How Bengaluru is solving traffic woes using AI

“We have 103 B-ATCS signals currently in operation. By March end, phase-1 would be complete taking the total to 165 such signs being operational around the city,” MN Anuchet, Joint Commissioner of Police for Bengaluru Traffic told indianexpress.com.

Talking about the outcomes, Anuchet said that there has been a reduction in travel time by about 15 to 17 per cent, an increase in vehicular throughput at junctions by 20 to 22 per cent, and a reduction in manual operational of signal from 35 per cent to less than five per cent.

This technology has been designed and developed in collaboration with the Japan International Cooperation Agency (JICA) and incorporates Japan’s MODERATO technology and can be controlled and monitored from a centralised traffic management centre.

A VAC signal unit comprises AI-powered cameras capable of analysing and measuring traffic flow and a Composite Signal Control Strategy (CoSiCoSt) that makes real-time decisions and enables communication with other VAC signals. Together, these components work in real time to adjust the duration of green signals based on the volume of traffic. For instance, if there is heavier traffic in one direction, people travelling in the other direction may have to wait slightly longer.

This system continuously monitors traffic, computes the optimal signal timings, and implements them dynamically while also using real-time GPS data, if needed. It has been specifically designed to cater to Indian driving and traffic conditions.

To address the unpredictability of signal changes, the Bengaluru Traffic Control (BTC) is working on implementing a five-second countdown timer before signals turn green to keep motorists informed.

“The new VAC system works well during peak hours, as it prioritises traffic flow on routes with more vehicles. However, at quieter signals, it can be tricky. Drivers often take a few seconds to start moving, and that delay makes it harder to clear the signal,” said Manjunath S., an IT professional who commutes daily between Vijayanagar and Koramangala.

However, it seems not everyone is pleased with the VAC system. Akshay Kumar H.C., another IT professional who commutes daily between Yelahanka and Marathahalli, said that the system often makes one side wait longer just to clear another side of the route. “Sometimes it changes the signal from green to red suddenly, which I noticed during the initial days. It added to the confusion of commuters,” said Akshay.

According to BTC, these AI signals operate automatically about 90% of the time, switching between VAC and ATCS modes during peak hours. Manual intervention is required only around 5% of the time to manage movements for VIPs and ambulances.

Currently, over 100 junctions across the city are equipped with VAC signals, reducing traffic congestion by up to 33% across 75 junctions powered by ATCS, as reported by the BTP. By the end of March, Bengaluru will have an additional 65 VAC signals by March and 300 traditional signals will be converted into VAC signals in the next phase.