A new traffic sign informs afternoon rush hour commuters to yield to traffic inside a traffic circle in Halifax.Paul Darrow/The Globe and Mail
I read the story about the rules for roundabouts and they make sense: Yield to traffic in the circle and signal when you exit. But I’m still wondering whether roundabouts actually make intersections safer. I still see drivers, including some in my family, who don’t seem to know how to use them. – Lee, Ottawa
When they’re designed properly, roundabouts generally make intersections safer because they slow traffic, a safety expert said.
“You’re reducing the speed,” said Craig Lyon, director of road safety engineering at the Traffic Injury Research Foundation (TIRF), an Ottawa-based road safety not-for-profit. “And you’re reducing the number of conflict points (areas in an intersection where cars can hit each other).”
Because all the cars are all going counterclockwise in a roundabout, cars aren’t turning left across oncoming traffic like they would in a normal intersection. Because of that, “you wouldn’t have head-on (or T-bone) collisions,” Lyon said. Instead, roundabouts tend to see lower-speed rear-end collisions and side swipes with less chance of serious or fatal injury.
“You probably will have some property damage to your car,” he said.
In the United States, studies have shown that changing an intersection to a roundabout from one with a stop sign or traffic lights reduced injury-causing crashes by 72 to 80 per cent and reduced all crashes by 35 to 47 per cent, according to the U.S. Insurance Institute for Highway Safety (IIHS).
But there doesn’t seem be much of a change in crash rates when a four-way stop is converted to a roundabout, Lyon said. “Typically, they don’t do that, anyway.”
Learning curve?
The safety gains aren’t as great, however, when roundabouts have more than one lane, Lyon said.
“When there are multiple lanes, there tends to be more traffic and it [also] gets more complicated for travelling through,” he said.
But a 2019 IIHS study in Washington state, which has more than 300 roundabouts, showed that crash rates at double-lane roundabouts decreased every year after a roundabout was built – about 9 per cent a year – as drivers got used to them.
To improve safety over a standard intersection, roundabouts need to have lower posted speed limits and clear signage and road marking, Lyon said.
Also, the roundabout’s roadway has to be wide enough to allow bigger vehicles, but not so wide that you can drive through the roundabout without having to slow down – which defeats the point of roundabouts, Lyon said. Also, if the roundabout isn’t curved enough, it won’t slow traffic enough to have a safety benefit over traditional intersections.
“If you can go though and barely have to turn the wheel, there will be people that will drive right through without slowing down,” he said. “It has to be designed to force people to slow down.”
That’s not the only question we received in response to our column on roundabouts. Here’s one from Alberta:
Should I use my left signal when entering a roundabout?
I’ve been driving for years and roundabouts still make my head spin. I know you’re supposed to use your right signal when leaving a roundabout, but is it a good idea to signal when you enter so other drivers know your next move? For example, if I’m taking the third exit on a roundabout, should I signal left to show that I’m not turning right or going straight through? – Denise, Calgary
When you enter a roundabout, it’s a good idea to be straightforward and let other drivers know where you want to go, a driving expert said.
“Always signal any time you enter a [traffic circle] or roundabout, no matter the size or how many lanes,” said Ryan Lemont, manager of driver education at the Alberta Motor Association (AMA). “This helps communicate your intention to other drivers and helps other drivers know your intentions.”
You should always signal right when exiting, but in most provinces, the rules of the road don’t specify how to signal when entering.
So, if you’re not taking the first exit, you could keep signalling left until you’re ready to exit, and then signal right when you’re leaving, he said.
Have a driving question? Send it to globedrive@globeandmail.com and put ‘Driving Concerns’ in your subject line. Emails without the correct subject line may not be answered. Canada’s a big place, so let us know where you are so we can find the answer for your city and province.