We received a couple of questions recently about traffic and traction. This isn’t the typical type of traction query we get this time of year (most of those are focused around winter tires and chains). To paraphrase, the first question went something like this:
With lots of use, do paved roads get more slippery over time?
It’s an interesting question, and one that intuitively makes sense. If you have a lot of traffic travelling a road, all that friction should gradually wear the pavement down smooth, creating a slippery surface.
Thankfully, the engineers that design our roads have taken that possibility into account and have developed strict standards about the type of rock used in our pavement – they need to be durable and angular to provide the best traction possible. Softer rocks, which could easily round over time aren’t used.
In fact, as a pavement ages over time it usually becomes a bit rougher, as the oil becomes more brittle and small cracks start showing up in the pavement. That’s where crack sealing comes in, and that brings us to the second question:
Do roads become slippery after crack sealer has been used?
Every spring, our maintenance contractors seal a lot of cracks in our roads. They usually use about 2 million metres worth every year, so you’ve probably seen these black strips on the road.
Once the sealant is applied, loose sand is put on top. The sand prevents the sealant from sticking to the tires of passing cars while it is curing, helps the sealant bond with the rest of the road surface and increases traction for vehicles that drive over it after the sealant has set, which takes a few days.
During that time, the sand can be an inconvenience and can make the road surface more slippery than normal. So if you see some recently sealed cracks, you’ll want to reduce your speed and drive a little more carefully. After the sealant is ready, our maintenance contractor will sweep the excess sand away.