[flickrslideshow acct_name=”spacing” id=”72157625981981811″]
__________________
The above images were posted recently by Kathryn Hunt on her Incidental Cyclist blog. Kathryn is an all-season cyclist and in the winter months she often documents the challenges and hazards of staying on two wheels in the slush and the ice. As thaws come and go, by February a new cycling hazard appears — the kind of tire-flattening, rim-bending potholes seen in the pictures above.
Looking at them something becomes clear – a hell of a lot of potholes appear in the curb side lane, close in to the sidewalk, near the gutter drains. That’s where you would expect the freeze-and-thaw cause of potholes to be at the worst, of course. The cracks nearest the drains fill with water which turns to ice and pries them further apart, the next thaw attracts more meltwater, and the next freeze opens the cracks even wider.
So why do we engineer our streets to drain to the curb, where the potholes are most likely to create serious hazards for cyclists and the puddles they contain are most likely to splash all over pedestrians? Basically, that’s what West Side Action’s Eric Darwin was asking last fall, with this post:
I think we will continue to have drainage problems … as long as we continue to design our rights of ways for cars and not pedestrians. For pedestrian benefit, drainage should be away from the curb to catch basins in the centre line of the street. This would have the additional benefit of making the street undulate from basin to basin, which would reduce speeding. Got that? It’s that simple: drain away from sidewalks, not to them. Encourage pedestrians to walk on the dry parts, not the wettest part of the road.
Away from the curb! It sounds so simple, and yet a prolonged image search turned up no examples of street drainage using such a technique. Amazingly, the only image I could find of “centre drainage” was not of a street, but of a sidewalk — in fact, a sidewalk recently rebuilt right here in Ottawa.
Laudably for the city engineering department, the principle behind this sidewalk rebuild actually seems to have been somewhat innovative. Water will still splash up from the curbside to the sidewalk, but at least a given puddle will only do so once, unlike typical slanted sidewalks that would drain the water right back down to the street, to be splashed all over someone again.
So do we dare to imagine that Ottawa could ever take such an innovation to where the rubber hits the road?
4 comments
FYI – the flash slide shows used on your site do not work on any of the iPad/iPod/iPhone devices. You might want to consider looking into an alternative that doesn’t use Flash.
In the last few years, the City has moved to the drains that are tucked into the sidewalk, rather than at the edge of the road. This reduces the potholes, which were caused because the concrete catchbasin under the road around the gutter didn’t settle the same way as the bedding for the asphalt.
As for draining away from the curb, I don’t really think it’s a good idea, for a number of reasons:
– The tilt means that cyclists and motorists drift into the middle of the road, and potentially into oncoming traffic
– I suspect the current road profile is more architecturally sound. Being convex, it can withstand the weight better (like a roman arch) than a concave surface, which could separate from the sidewalks and create even BIGGER cracks/potholes at the road edge.
– We’d have to plow snow into the middle of the road, whereas currently if there’s a big snowfall that makes the road narrow, motorists can cross to the other side to pass other vehicles etc.
– If we still plow snow to the edge of the road, then we’ll get much more ice covering the road surface during freeze/thaw cycles
Charles,
I think I’d sooner have wayward cars drift into oncoming traffic than drift into cyclists and pedestrians off to the side… At least drivers coming the other way can see the wayward car and have several hundred pounds of steel cage around to protect them.
I also see no reason why we’d have to plow to the centre. Ice is unlikely to form when the water has a place to go (the central drains) rather than just standing around dammed by snowbanks. With all the salt we put down it’s even less likely.
As for the road profile, asphalt doesn’t have the kind of load-distributing strength that concrete has, so its profile really doesn’t matter much. That’s why asphalt fails at heavily-used bus stops and places where lots of trucks stop and it’s why we get “wheel tracks” on heavily-used highways.
Draining to the centre would pretty much remove the biggest cause of damage to asphalt, which is water infiltrating into cracks and into the roadbed from standing pools of water and then freezing/thawing. When water is drained to the outside, it runs the risk of being dammed by snowbanks blocking the drains.
As a pedestrian, I find nothing more annoying than encountering great pools of water trapped between snowbanks at street corners/crosswalks (being soaked is in the downright unpleasant category).
At the very least, we should do some trial runs on a few streets and see what the results are like.
Maybe people who hate all the water caused by — gasp — melting snow should consider relocating to warmer climes.
I dislike huge spring puddles as much as the next person, but asking/hoping for a redesign of all the streets to a non-standard, non-proven configuration seems like a pipe dream to me 😉