What are these black circles puzzling Metro Vancouver drivers?
Some drivers in Metro Vancouver are scratching their heads, wondering what the black circles at Metro Vancouver intersections are and if they have any purpose.
Alex Green shared a photo of an intersection in Port Moody with circles in the pavement that can be seen placed in some lanes.
In a Facebook group, he shared a photo and said he thought it could be used to teach autopilot cars to recognize intersections and stop.
“It seems crazy enough to be true,” he said.
Since posting, hundreds of people have commented and many have admitted they don’t know what the markings are for.
So, we reached out to the City for clarification.
Alex Grein/Facebook
Hint: It’s not tire marks
Nobinur Rahman is a transportation engineer with the City of Port Moody. He explained that the black circles at various intersections are inductive loop sensors.
“These sensors are installed in the road’s surface and work by detecting changes in the magnetic field when a vehicle passes over or stops above them,” he said. “The primary goal of these sensors is to optimize traffic flow.
“By detecting the presence of vehicles, the sensors inform the traffic signal controllers when to change the traffic lights, which helps ensure a smoother flow of traffic and can reduce unnecessary waiting times for vehicles based on real-time conditions.”
Alex Grein/Facebook
He said these sensors can be, but are not always, used to activate or extend the time for traffic movements, including left turn arrows.
All traffic signals and sensors are owned and operated by the City, and the exact function of inductive loop sensors can vary depending on the intersection and jurisdiction.
Video cameras on roads are also used for vehicle detection.
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If you are a driver, you may have noticed other vehicles trying to align their car to the sensor to trigger the traffic light in a certain direction. Daily Hive was not able to confirm whether this would impact the traffic light. Rahman said the City cannot comment on whether a driver can use the loops to achieve a desired outcome. However, he said, City traffic signals are designed to work best based on typical driver behaviours.
“Drivers should at all times prioritize safe and defensive driving practices,” he said.