Green Light: Quebec City uses AI to manage traffic

Traffic light (Pexels.com)

Quebec City has turned to Google’s artificial intelligence (AI) to synchronize traffic lights, which officials say will improve traffic flow, reduce congestion, and lower greenhouse gas emissions.

According to Google Canada, Quebec City is the first city in the country to partner with the web giant’s Green Light project.

As part of this project, AI analyzes driving trends from Google Maps and combines this data with information on the location of traffic lights in the city.

“The Green Light project uses driving trends from Google Maps and artificial intelligence to map a city’s traffic patterns and then make specific recommendations for specific intersections that can be implemented very quickly by city engineers,” explained Laurence Therrien, public affairs manager at Google Canada, in an interview with The Canadian Press.

She clarified that AI data won’t replace the work of engineers, but rather serves as an additional tool.

“The aggregated and anonymized trends from Google Maps really give a much faster and more reliable overview of a city’s traffic than if it were done manually or with existing systems,” she said.

Present in some 20 cities

The Green Light project is being used in 19 cities on four continents.

According to a data analysis conducted by Google in these cities, the project has “demonstrated the potential to reduce frequent stops and starts by up to 30 per cent and estimated CO2 emissions at urban intersections by 10 per cent.”

Google’s AI aims to make car traffic flow more smoothly.

If a city emphasizes smooth car travel, does it risk encouraging more people to use their cars, to the detriment of active or public transportation?

“If car traffic flows more smoothly, so does bus traffic,” replied Therrien.

“So it encourages public transportation, which is much more efficient than if traffic lights are not automated,” she said.

Initial positive results in Quebec City

In Quebec City, the project has already made it possible to adjust the timing of traffic lights at 11 intersections in the city, and the initial results are positive, according to Mayor Bruno Marchand’s administration.

“An innovative project like Green Light allows us to quickly and effectively optimize our road network, thereby improving traffic flow and efficiency,” said Marchand in a press release.

A compelling example

In the press release issued Monday morning, the City of Quebec “gave an example of the project’s impact.”

The municipal administration explained that during the evening rush hour, traffic lights were “slightly out of sync” at the intersection of Côte Saint-Sacrement and Semple Street, at the corner of Charest Boulevard, causing delays for drivers travelling down Côte Saint-Sacrement and leading to traffic jams.

“Using the Green Light AI model, Google proposed reducing the gap between the lights by 15 seconds to align the timing with those at Semple and Charest,” and “northbound travel, which is the most frequent in this area according to 2023 data, is now smoother and better coordinated.”

This example shows how AI “can complement the work of municipal experts by proposing simple, effective, and data-driven adjustments,” according to the city.

The Green Light project is available free of charge to cities that wish to use it.

- This report by The Canadian Press was first published in French on Aug. 18, 2025.