Wednesday, September 7, 2011
I've been wondering how, exactly, the city has been counting bicycles on its new segregated bike lanes on Laurier Avenue, and feeding that information to the daily tally on ottawa.ca. Those numbers seemed awfully high to me, and I'll admit to some skepticism.
So here's how it works: There are two counters embedded in the asphalt near the intersection of Laurier and Metcalfe, one in the eastbound bike lane and one in the westbound. You may have rolled over them without noticing. It's that elongated diamond shape in the lane.
A spoksperson for the company that makes and installs the counter explains how those sensors count bikes, and just as important, how they avoid counting cars and other objects. "It's an inductive loop, and it emits a force-field if you will that's broken when a bike passes over it," says Eco-Counter's Ryan Whitney. "It uses 13 different parameters to measure the presence of a bicycle. It measures the beginning and the end of the wheels on a bike. If a pedestrian passes over it, it will not count the pedestrian, it will only count the bike."
Once the bike passes over the loop, the count is transmitted to a cylindrical logger, which is also under the asphalt. If outfitted with a modem, as Ottawa's are, the counts can be relayed automatically to a web site for anyone to see. Similar systems are up and running in Vancouver, Toronto, Montreal, Quebec City, New York City, Portland, Chicago and Washington D.C., just to name a few. The NCC has apparently adopted similar technology as well. Here's a pic of a familiar Ottawa site, before the top layer was put down.
These additional sensors aren't feeding tallies to the on-line counter just yet. That means there could be hundreds of trips that aren't being included in the count. If for example I join the lane at Bronson but end my trip before I reach Metcalfe, I won't be counted. So there may be even more cyclists using the Laurier lanes than the city's numbers suggest.