HOW DO WE WIN THE WAR ON POTHOLES?
There are some uniquely Canadian solutions to the rot that plagues our roads
Well, here’s one more thing for which we can blame global warming: Potholes.
Far-fetched? Not according to Susan Tighe, the University of Waterloo’s Norman W. McLeod Professor in Sustainable Pavement Engineering.
Back in the days when Canada’s seasons could be divided into nine months of winter and three months of road construction, the deterioration of our roads was pretty straightforward. Moisture — rain, snow or whatever — would find its way under the pavement ( between the top asphalt layer and its granular substrate) and freeze. Said water, now frozen, would expand, creating a bulge in the roadway. Come spring, the ice would melt and the water disappear, leaving the bitumen to either crack or collapse.
This obviously weakened the pavement and eventually that patch of asphalt would peel away, leaving a pothole.
The only good thing about the process was that it only happened once a year.
Now, says Tighe, it happens all winter long, as a result of the rapid temperature fluctuations that plague every season.
These rapid heating/cooling changes create the same freeze/ thaw/bulge/crack/collapse cycles that used to happen primarily in spring. And though it would be an exaggeration to claim these micro-climates never occurred in winters past, it’s also true rapid temperature spikes are on the rise.
OK, but why do our roads, once repaired, deteriorate so fast?
The main reason is increased traffic. While that freeze/thaw cycle is stressing our pavement from underneath, the larger number of vehicles — especially heavy tractor-trailers
— is pounding it from above. The problem is that while they appear rigid, our roads are actually designed to be quite flexible — “viscoelastic,” as Tighe calls it — and they bend and distort much more under the impact of one heavily loaded tractor-trailer tire than a whole bunch of car tires.
While many of the problems are simply physical and their solutions — thicker pavement that withstands heavier loading — well known, one of the biggest issues affecting the long-term health of our roads is plain old human indulgence. According to Tighe, our unwillingness to be inconvenienced greatly affects the quality of our roads.
“The public needs to be open to closing roads for regular maintenance” so work crews can provide proper repair. But because closing major highways and arterial urban streets is often unthinkable — or at least politically inexpedient — compromises are made.
One of the reasons repairs to Toronto’s Don Valley Parkway are done right is that the thoroughfare is often closed for 24 to 48 hours for crews to effectively complete repairs.
One of the biggest problems is that repair crews don’t know where the potholes are. That’s ridiculous, I can hear you screaming, because the damnable road conditions you see every day seem obvious to anyone.
But that’s just the point; you see them every day. Municipalities, or the civil engineering firms they hire, have to identify and quantify each and every crack and crevasse to prioritize them for repair.
According to John Zelek, co-director of the Vision/Image Processing Lab at Waterloo, that’s accomplished either by (in affluent communities) cameraequipped cars or, in smaller cities, by literally driving around with pen and paper and noting where the bumps are. Either way, it takes months.
A better solution, says Zelek, is to equip civic vehicles — police cars, fire trucks, etc. — with cameras and then feed their images to computers that can categorize the road damage automatically.
It could get even simpler, claims Zakariya Gadi, a Concordia University civil engineering Master’s student, who developed a pothole-detection system earlier this year that uses nothing more exotic than a smartphone; Gadi used an old Galaxy S4 in his testing.
I know “Measuring the Impacts of Climatic Exposure to Pavement Deterioration with Low Cost Technology” may sound about as boring as an Andrew Scheer speech, but considering that we spend $12 billion each year maintaining our roads, Gadi’s Samsung could be a real tax saver.
It’s a homegrown solution to a uniquely Canadian problem.
We may win the war on the potholes yet.