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Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 8:43 am
by Sweeper59
I work for a Traffic Engineering company, and was recently involved in the design of a major intersection upgrade. The works included the installation of detector loops within the pavement at the approaches to the intersection. Some of my cycling mates recently asked me if these detectors are triggered by the weight of vehicles, and questioned whether the weight of a bike + rider has any impact on the system. The detectors are actually NOT based on weight, and work by sensing objects passing through electromagnetic fields. According to the contractors installing the detectors, the best way for cyclists to trigger these detectors is to ride directly over the actual wiring, which is generally under the edges of the rectangular shape you can generally see within each lane of the roadway. Like many others, I used to ride through the centre of the rectangle.

Re: Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 8:45 am
by AUbicycles
That is really useful info. I find on my Carbon Fibre road bike, I have trouble triggering the lights at all.

Re: Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 1:33 pm
by Nobody
http://www.humantransport.org/bicycledr ... ection.htm" onclick="window.open(this.href);return false;

From:
http://www.bicycles.net.au/forums/viewt ... p?p=139060" onclick="window.open(this.href);return false;

Re: Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 2:26 pm
by find_bruce
I wrote a lengthy post but that failed to post for some reason so you will have to put up with a short version. See RMS consultant's report

The loops are part of the problem - the ones on my commute are set with such low sensitivity that a bicycle needs to be positioned within 1 inch of the "diamond dot pavement markings"

The bigger problem is that the lights are not in any way co-ordinated with other intersections. You get a green bike light, ride to the next intersection, 93% of the time you will then have to stop, wait for around a minute for the lights to go through the phases, then ride on to the next intersection. Repeat for every set of lights.

If on the other hand you ride on the road, you have a 60% chance of riding through on a green light.

Apparently it comes as a complete shock to the persons writing the report that cyclists "appear frustrated at delays at successive, closely spaced intersections along a cycleway (because there is currently no coordination of bicycle green signals."

Re: Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 5:31 pm
by DavidI
AUbicycles wrote:That is really useful info. I find on my Carbon Fibre road bike, I have trouble triggering the lights at all.
When on my carbon bike I try to place it directly over the edge of the loop that runs in the same direction as I'm travelling. For good measure, once stopped I lean the bike over a little towards the drive side and turn the cranks a few times - the chain (being steel) will be disrupting the magnetic field, and I figure if it's moving it will disrupt it further. Seems to work pretty much every time.

Re: Pavement detector loops & how to use them

Posted: Tue Oct 16, 2012 6:21 pm
by scotto
Nice to know. There's at least two intersections I use a lot that just won't change for me so now I generally just run the red light (it's usually 530am though). I always stopped on the middle