Monday, December 22, 2008

The Traffic Lights Turned Green for Christmas

I wonder if reader Purple Haze can identify that reference to Jimi Hendrix...

I wrote earlier that traffic engineers at Louisville Metro were looking into how to make the inductive loop traffic detectors in our fair city respond to bicycles. A couple of weeks ago, their efforts and mine started to pay off. Dirk Gowin, who oversees bicycle and pedestrian transportation programs for the city, met me and two traffic signal technicians at the corner of Spring Street and Payne Street to test the loop detectors with various bicycles. As usual, only the less busy of of the two streets (Spring Street in this case) has loop detectors. One of them would detect a steel diamond-frame bicycle, but not my mono-tube recumbent bicycle. The other would not detect any of the five test bicycles. To my amazement, the technicians needed only to change the sensitivity setting on the detector circuit board to make the first detector respond to all of the bikes. For the other loop, swapping one circuit board for another made the signal responsive to all of the bikes. Voila! an intersection fixed!

From there, we went to five other intersections. With one exception (apparently due to a problem in the underground loop itself), the technicians made all of the loops sensitive to all of the bicycles. The other newly bicycle-sensitive signals are located at:
  • Payne Street and Lexington Road
  • Payne Street and Baxter Ave. (westbound only; the eastbound loop appears damaged)
  • Bellaire Ave. and Frankfort Ave. (the first signal west of the railroad crossing on Frankfort Ave.)  Have patience - this signal takes 45 seconds to change.
  • Hillcrest Ave. and Frankfort Ave.
  • Bauer Ave. and Frankfort Ave.
Weather permitting, the crew will go out again a week from today to reset another several traffic signals to respond to bicycles. I have provided a list of ten more intersections in the Highlands, Original Highlands, Cherokee Triangle, Clifton, St. Matthews, and farther out US 42. If you know of signals with loop detectors that will not respond to bicycles, please e-mail the locations to and I will add them to the list. We can't guarantee a quick fix to any intersection. If the wire loop buried in the pavement does not work properly, the signal probably won't get fixed  until the next repaving of that street. Given the city's interest in making the signals work properly for bicyclists, though, I expect we'll see lots more progress over the next few months. Thanks again to Dirk Gowin and Pat Johnson of Metro Public Works for making this happen.

A final reminder: At least until Metro Public Works begins stenciling bicycle logos on the sweet spots of the loop detectors, you will need to know where to place your bicycle to trigger the signal. For a dipole loop (which looks like a rectangular outline on the street with its corners cut off), place your bicycle on the line along the right or left edge of the rectangle. For a quadrupole loop (which looks like a long dipole loop, but with another line running lengthwise down the middle of the rectangle), place your bicycle on the middle line. In either case, you do not need to move the bicycle beyond the stop bar painted on the ground. Anywhere on the line of highest sensitivity should trigger the detector. If you have trouble with any of the detectors mentioned above, write to me and I'll try to get it repaired.

1 comment:

bikeolounger said...

I must admit that I don't know the ouvre of Jimi well enough. I've also dropped the moniker "purple haze," which was a temporary one in the first place, now that I've sorted out the sign-in hiccoughs that led me to create a second blog account. Besides folks will recognize me more under my more-common web name.

It's good that we have friends in key places that can help us be a more bike-friendly locale. I was pondering some earlier post here regarding timing of lights, and wishing someone who cares was operating that computer. Hopefully one or two of our key friends can help on this.