Tuesday, July 20, 2010

How to put in new sidewalk in a tough spot, without breaking the bank

Most of Van Dusen Road has drainage swales on both sides of the road.  These "ditches" catch rainwater runoff from the road and filter it into the earth and direct it to larger stormwater management systems.  These ditches work fine for rural roads. The problem is that Van Dusen Road has lots of development on it and lots of pedestrians - it is not rural - and it needs sidewalk.  However, one can't simply plop down sidewalk above the road-grade without redirecting the flow of water to someplace where it shouldn't be.  Retrofitting ditches with concrete piping and stormwater catch drains/basins to alleviate this becomes extraordinarily expensive. The Laurel City Department of Public Works came up with a nifty solution to install sidewalk along Van Dusen Road that utilizes the existing drainage ditches, but also builds above-grade sidewalk. The initial segment of new sidewalk to take advantage of this solution is this segment of Van Dusen Road that leads from the intersection of Cherry Lane to the entrance of the Laurel Oaks development.  As shown in the picture below, it is well traveled and in need of sidewalk, as Van Dusen also has its fair share of speeders.

The new solution involves utilizing a concrete flume, extending from a new gutter, that runs underneath the sidewalk panels, at predetermined intervals. 
The flume allows water that is caught by the gutter to exit out into the ditch, as before, yet still allows for uninterrupted sidewalk. The sidewalk panel over the flume is reinforced with 1/2" rebar, because of concrete's weak tensile strength.  This covered-flume solution has been installed along Van Dusen between Cherry Lane and Laurel Oaks for the past 2 months and appears to be working as intended.  Provided it continues to hold up well, this system allows for continuous concrete sidewalk to be installed along the remainder of Van Dusen without the prohibitive costs of brand new stormwater management systems.

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