Ask RIDOT: Bicycle traffic-light sensors are not coming any time soon



Ask RIDOT: Bicycle traffic-light sensors are not coming any time soon

I sent a question about traffic-light sensors into “Ask RIDOT” a while back and just happened to notice they answered it. The bottom line appears to be:

RIDOT does not currently use bicycle detection at signalized intersections. The Department has not researched the operation and efficiency of these detection systems yet. That does not mean, however, that we are opposed to installing them.

I’m still curious whether it’s significantly more expensive to install these newer sensors, as repairs are completed. RIDOT’s suggestion for how to get around the problem:

In the meantime, we recommend using the push button provided for pedestrian crossings at signalized intersections. This is a much safer alternative than proceeding through a red light.

is completely ridiculous. Perhaps we could legally require motorists, waiting to turn left at an arrowed intersection, to get out of the car and run around it until the light changes for them. This would make about as much sense as trying to trip a light, moving over to the pedestrian area, pushing the button, and then moving back into the travel lane.  I’ve got a lovely intersection on my way home, where it would be far more dangerous for me to try and get over to the pedestrian crossing light, than it is to turn left through a red arrow.  I’d be happy to take a ride with someone from RIDOT and show them how challenging this would be.

Sorry RIDOT, but I’d still prefer a roadway that works for my vehicle.


  • Don Rogers
    Mar 7, 2008 at 5:20 am

    Most roads we ride on would be maintained by city highway departments, not RIDOT, and city officials are both much more aware of sensor technology and able to change their settings. It's worth a call to your Town Hall to ask about intersections that are not properly detecting bikes; they often can send out a crew to ratchet up the sensitivity.

    For those who may not know, if you can see the cuts in the pavement where the sensor loop is installed, the most sensitive position is directly over one of the cut lines, and especially at a corner. The sensors work on changes in induction in an electric field, not magnetic fields, so any metal (not just ferrous metal/steel) will trip them, even the aluminum in your wheels.

    In most cases if a light goes through 2 cycles or 3 minutes without detecting you, it is legal to consider it defective and ride through it when traffic conditions allow. Otherwise, that pedestrian-signal method, though silly, is also a valid option.

  • Mar 7, 2008 at 6:31 am

    Don brings up a good point, however, in my experience, I think most of the roads where I have problems tripping lights are maintained by RIDOT. It's typically when I'm sitting and waiting for a left turn arrow and end up waiting through a couple cycles of the light without getting the arrow.

    I road into work a different way this morning and had problems tripping the light. It didn't have any pedestrian light controls, so the workaround would have done me no good. I'll have to check and see whether it's a RIDOT or Barrington maintained road. Somewhere I have an email with a link to a site listing RIDOT maintained roads, I'll try and dig this up and post it on the site.

  • Jun 19, 2008 at 10:01 am

    The April/May issue of Public Roads magazine has an article on Making Signal Systems Work for Cyclists. The conclusion they come to is that

    The study’s results showed that the settings and location where a cycle crosses the loop, not the design and installation, are mainly responsible for the poor detection of small vehicles.

    The good news is that the loops are able to pick up bicycles, so no change in technology should be necessary to make lights work properly. Unfortunately though,

    many engineers and technicians are reluctant to use higher sensitivity levels because the settings may cause detection of highly conductive vehicles in adjacent lanes and may cause cross talk or interference between loops.

    There are a few types of newer loops that fair much better at picking up bicycles, the layout of the induction loop is fundamentally different. There are also a number of cities putting down paint over the loops, instructing cyclists where to sit, to maximize the chances they are detected. Both of these are steps RIDOT could take as they repair or replace current loops to help out cyclists.