Pothole Season Is a Safety Season

A pothole means something different depending on how you travel. In a car, it’s a jolt and maybe a bent rim. On a bike, an e-scooter or a motorcycle, a front wheel that drops into one can throw you. In a wheelchair or behind a stroller, a broken edge at a crosswalk can stop you cold. And a driver swerving around one ends up in somebody else’s space. So I set out to map Edmonton’s potholes as a safety problem: when the risk peaks, where it sits, and how long it lasts.

The City’s 311 Explorer has every pothole report since 2014, with exact coordinates, more than 150,000 of them. I turned each season into a density surface and drew it on the street network. Road lines get wider with the posted speed limit, the same styling as my speed-limit map, so you can see where damage and fast traffic overlap.

When the risk peaks

Every spring a bloom of reports spreads out from the core along the arterials. In a typical year, the eight weeks from mid-March to mid-May hold about a third of all reports. That’s exactly when people pull their bikes out after winter, and when melt and grit already make the edge of the road the worst place to ride. The roads are at their roughest right as more vulnerable users return to them. September and October are the quietest snow-free stretch. Winter looks calm too, but only because snow hides the damage.

Where it sits

The brightest contours run along the wide, fast corridors, where a sudden swerve carries the most risk and there’s the least room to make one. Downtown has the most reports overall. Measured per kilometre of road, though, the University of Alberta area, the river valley along Whitemud and Callingwood South lead. A safety lens needs both views: the busiest places and the most damaged ones.

How long it lasts

A pothole is only a hazard until it’s fixed. In October 2026, 367 reports from the past year were still open, and 223 of them had been waiting three months or more. They cluster in a handful of west-central neighbourhoods. A hazard reported in April and still there in July has been through a whole cycling season.

How I made it

Reports are smoothed on a 50 m grid and contoured with a turbo colour ramp. The surface fades to nothing between 50 and 150 m from the nearest road, which keeps the river valley and the ravines honest. The river and bridges are drawn on top, and a few muted street labels help you stay oriented.

Caveats

A 311 report measures complaints, not potholes and not injuries. About 40% of tickets repeat an address already reported that week, and busy roads get reported more simply because more people use them. Freeze-thaw cycles don’t explain the bad years, so some of the year-to-year swing is about reporting rather than the roads. The natural next step is to set this against Edmonton’s collision data and see whether pothole hot spots and crash hot spots share the same streets.