Ottawa·Point of View

Are traffic sensors common sense for pedestrians, cyclists?

Traffic sensors help determine when traffic lights change at busy intersections, but for cyclists and pedestrians, could the system be dangerous?

Giacomo Panico, host of CBC Radio's In Town and Out, wonders if traffic sensors can pose a danger

Giacomo Panico showcases traffic sensors

10 years ago
Duration 0:34
Take a look and listen as the CBC's Giacomo Panico explains how traffic sensors work.

Efficiency vs. Safety?

What do you think? Tweet @giacomopanico and we will gather your reaction.

You're probably already aware that most traffic lights in Ottawa are linked to sensors under the asphalt. When you roll up to a red light in your car, the sensor detects your presence and hopefully you get a green light sooner than you otherwise would. It is the same for cyclists when the intersection has the three yellow dots that sense bikes. 

But watch what happens in the video above. It's a situation I've spotted at many intersections in Ottawa and it's not a glitch. It starts with the traffic on Holland Avenue having a green light. I'm exiting Fisher Park Public School and I have a red light. 

What's happening?

The intersection senses my bike and begins the sequence of giving Holland a red light. It makes it all the way to giving Holland a red. But just before giving me a green (while both lights are red), the system does one final check to make there's still a bike or car needing the green. I've moved a couple of feet off the pad, so it assumes no one is waiting and goes back to green for the traffic on Holland.

Why is it doing this?

The city tells me the traffic lights are programmed this way to account for cars making right hand turns. Let's say a driver leaves Fisher Park school and wants to make a right turn on Holland. They stop at the red light and wait for a gap to turn right. While waiting, the car has triggered the sensor.

The system begins the process of eventually giving the traffic on Holland a red and that driver a green. But what if in the time before the car gets a green, it was able to make its right turn? The city's engineers say that would be an unnecessary red for the traffic on Holland. 

So the system does one final check: when the light on Holland is red, but before giving the car exiting Fisher Park a green, it checks to make sure that car is still there on the sensor. If it isn't, then no need for a green coming out of the school and it's right back to a green light for traffic on Holland. The city calls this feature a "Revert Red."

To be clear, the system is making this decision even after giving the traffic on Holland a red light. This is not the crosswalk signal resetting. My concern is when you go as far as to give one direction a red light, then you're really creating an expectation in users that they will get a green light. 

Yes, I realize no one should begin crossing an intersection until they get a green light or walk signal. But does this Revert Red account for real-world use? 

Take the case of a pedestrian who sees the street they're about to cross has just gotten a red light, so they start their walk a tad early. But surprise, suddenly they find themselves in the middle of the road as the traffic goes back to green. 

What do you think?

Tweet @giacomopanico and we will gather your reaction.