In civil engineering-speak, curb radius refers to the curve of the curb as it goes around a corner; sometimes it’s a wide gentle bend, and sometimes it’s a tight right angle. So here’s a question: when’s the last time you waited at an intersection for the light to change and actually even noticed the curb radius? If you’re like pretty much everyone else, probably never.
And yet, believe it or not, the curb radius is one of the most important components of streetscaping, and has a profound influence on how drivers and pedestrians use a street.
As you already know, streetscaping refers to all the elements making up the public spaces along our streets. Because a key vivaNext goal is to make everyone feel welcome on our streets, whether they’re walking, biking, waiting to hop on Viva, or driving, we pay a lot of attention to streetscaping considerations. This includes the curb radii for every single intersection and entrance along our rapidways.
The curb radius describes the shape of a corner, such as when two perpendicular streets come together at an intersection, for example. The curb radius is expressed as a number, taken from the radius of the curve connecting the curbs of the two streets. On a wide suburban corner, the curb radius might be as high as 35, whereas on an urban street corner, it might only be 2.
Most urban settings, including along our vivaNext rapidways, aim for a smaller curb radius wherever possible. That’s because the smaller the curb radius, the shorter the distance a pedestrian has to walk to get to the other side of the road. A smaller curb radius has other impacts too. It results in more space at the corner, including more space for accessible ramps. It makes it easier to line up crosswalks with connecting sidewalks. It improves the sightlines for pedestrians and makes pedestrians more visible to drivers. And it slows down turning movements for vehicles going around corners, which is safer for pedestrians.
Of course, curb radius design also considers the needs of drivers, including traffic volume, vehicle size, and their desired speed going around corners. It also has to take into account bike lanes, on-street parking, bus stops, emergency vehicles, and other design requirements. Whether or not the road is part of a truck route may affect the curb radius, because trucks need a larger turning radius to be able to navigate turns while staying within their lane.
Our final curb radius design isn’t up to us alone, of course. Our designs reflect standards and requirements set by York Region and the municipalities as part of their broader planning for their regional and local road networks. Those requirements in turn reflect the design standards from a variety of authorities including guidelines from the Transportation Association of Canada and the Ontario Ministry of Transportation.
There’s a lot involved in the design of a simple concrete curb than you probably would have guessed. But the final result is for a more welcoming, safe and accessible streetscape for all users.