Monday, March 1, 2010

Sidewalk Engineering



I have some tolerance for dilapidated infrastructure in the city. Not everything can be perfect. And I rationalize away some of the puddles at crosswalks as being products of 60 year old roads, old neighborhoods, etc.

This makes it doubly disappointing to discover that sometimes newly rebuilt roads and sidewalks are no better. The photo above is at the corner near Billy's Appliances on Richmond Road, beside Our Lady of the Condos. Yes, it is the final pavement, the catch basins were not unusually blocked (anymore than they are designed to be) ... its just that the sidewalk at the corner is the lowest spot around rather than a higher spot.

But its not as bad as this picture:


This is the brand new asphalt sidewalk and bike path leaving the Baseline Transit station. Looks deep to me. I expect to see ducks or geese there next time. The western city hall outpost of Centrepointe is in the background, the city's engineering depts are located in the Constellation Drive building slightly off screen to the right -- you know, the one with a hundred acres of snow parking lot, free, for employees, even though they are located right at a transit station.

I think we will continue to have drainage problems at intersections 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.

3 comments:

  1. I don't know how much of this is car-centric, whether deliberately or just out of ignorance of the needs of other modes, and how much is institutional history (after all, engineers have been draining roads from the centre to the sides since Roman times), but I think it's pretty clear that in conditions like we get in Ottawa where snowbanks and water can exist simultaneously to drain urban streets (i.e. curbed with sidewalks) to the outside is not a terribly good idea.

    In a rural or highway environment the traditional drain to the side scheme makes sense, especially since there are usually open ditches/swales that are very hard to actually block, and there are advantages to an outward-directing camber in terms of steering out-of-control vehicles off the road. But these factors don't exist in urban environments. Drainage is by storm sewer collected at intervals in easily-block catch basins, not continuously. Steering wayward cars off the road into the sidewalk is a worse idea than steering them into oncoming traffic.

    I'd like to say it's surprising that street design hasn't changed, but unfortunately it's not. One would have thought that centreline drainage would actually be cheaper since it just requires one line of catch basins in the centre above the storm sewer and no cross-street drains (or two storm sewers), as is required now.

    At the very least (and as a not-too-difficult retrofit) catch basins should be located at sidewalk depressions - it doesn't solve the problem of draining water towards pedestrians and cyclists but it does at least get rid of most of that water since these locations will tend to be clear most of the time.

    It's interesting to look at infill condominium townhouse developments - they often feature drainage to the centre of the laneways because the laneway is not just an access road but it is also an integral part of site drainage - i.e. its role with respect to the overall development is more often considered than is the case with public roads... rather ironically.

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  2. David: I agree with almost all you say. Just because roads were always designed to drain outwards is not a reason to do it today. The romans had no cars, carts and peds mix reasonably well as to speed, but not as to waste (in Pompeii it is possible to see stepping blocks that allowed romans to cross the street without stepping in shit). Medieval streets were centre drained, some are still in place in Oxford and Paris.

    It is not unexpected that the private sector innovates in drainage ... they have a bottom line. It is in their interest to make roads narrower, corral parking to be efficient, drain efficiently, etc. The city, withou cost constraints, cheerfully requires OTHER PEOPLE to spend their money on super wide roads, onstreet parking, obsolete drainage patterns. If the city stopped its largest single municipal function -- the provision of free parking -- we would have a much more economic city.

    At the risk of excessive controversey, I think smart growth measures are in large part misdirected because they result in outrageously unaffordable housing costs. What would be better would be more cost recovery and cost-based taxing. As long as taxpayers provide free parking and sell transit rides for $3 that cost $8... people will continue to do the same old same old.

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  3. Flat-rate (or flattish-rate) transit fares do make a lot of sense, in the same way that flat-rate lettermail rates do.

    On the other hand, many other services, including water and sewerage, garbage and recycling, street lighting and snow-clearing, definitely do cost more to provide to low-density, monoculture built-up areas, than do higher-density and mixed-use areas. There are about double the number of households paying to snow-clear, etc., my residential block, compared to a comparable length of side-street in, let's say, Alta Vista or single-family parts of Nepean or Bell's Corners.

    If suburbanites really want to hold the line on tax increases — zero means zero and all that — the only way to do that is to split the tax burden among more payers. And the only way to do THAT, is to allow for a greater diversity and density of built forms and land uses, in both future AND existing built-up areas.

    Unfortunately, the subset of "zero means zero" overlaps in very large measure with the subset of "Not In My Back Yard".

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