Given the unseasonably warm temperatures for this time of year, the Roads and Parking Services team have sprung into action to address what is inevitable with this type of weather pattern, pothole repairs. Roads staff will be taking advantage of the mild weather expected over the next few days by redirecting additional resources and deploying more crews to fill potholes.
Since January, Ottawa has seen all sorts of weather – it started off with freezing rain early in the month, the middle of month brought back-to-back snowfall events, snow squalls, temperatures above zero, and then just last week more freezing rain and rain. Staff know this winter season will wreak havoc on our roads, sidewalks and winter cycling network as the freeze / thaw cycles take hold this month, bringing with it an increased number of potholes. They are on the job and ready!
How are Potholes Formed?
Potholes are formed when water (from rain or melted snow and ice) seeps into small cracks or holes in the road. As temperatures drop, the water under the road freezes and expands pushing up on the road above, creating larger cracks – when the temperature rises above zero, the water evaporates and leaves an open space under the road. The weight of cars and trucks travelling over these weak spots breaks the asphalt, resulting in potholes.
How do we Repair Potholes?
Potholes are filled by cleaning the hole of debris and water, then packing it with asphalt and rolling or pounding it down. At this time of year, some potholes in high traffic areas may need to be refilled more than once. This happens because water works its way back into the hole preventing the asphalt from forming an adhesive bond with the pavement.
Filling Potholes in Winter
In winter, conditions are not ideal for pothole repairs. The unstable conditions, including ice and water in the holes, as well as the cold temperatures and frequent freeze / thaw cycles, prevents the patch from adhering as well to the roadway making the repair temporary. Products that staff use to repair potholes during the winter months are Cold Patch and Warm Mix asphalt.
Cold Patch asphalt is a blended asphalt material which can be stored for extended periods of time. It can be used in all temperatures, does not require special equipment to compact and can be applied directly to the roadway without heating.
Warm Mix asphalt can be used year-round and produced at a lower temperature using different adhesives in the mix. Once the material is heated, the adhesives become thinner allowing improved workability and flow. The material can be manually compacted with a tamper, or shaped and compacted with power plate tampers or rollers.
Based on the forecast, staff are anticipating several freeze-thaw cycles over the next few weeks. The city has already experienced 35 freeze/thaw cycles this winter season. Residents can expect to see our pothole crews across the City. Ottawa winters are hard on our infrastructure, and this year in particular, we are anticipating an increased number of potholes. Staff appreciate your patience as they transition between different winter maintenance activities and prioritize and deploy resources to complete our operations.
For residents wishing to report a pothole, a service request can be created online.