Photo above by Richard Masoner
This is a guest post by Steve Cable
When reading the Ngapipi Rd cyclist sign thread, I was reminded of a simple trick that will enable your bike to be recognised by traffic signals. The picture shows a detector loop where wires in the road electromagnetic field senses the presence of metal and to informs the signals controller of the presence of a car or truck.
Obviously, there’s much less metal in your bike than even a motor scooter, but by riding where the field is most sensitive, the signals can detect your presence.
When approaching the lights, you should see the loop on the road, ride along one of the lines (the arrows in the picture are offset to allow the cut line to show) which is where the detection field is strongest and the metal in the bike should trigger the lights for you.
This technique almost invariably works at traffic signals where you can ensure that you get a green light, or a green arrow if you’re making a right turn and has saved me a lot of unnecessary waiting at traffic lights over the years.
The loop that triggers the cyclist specific warning signal on Tamaki Drive (pictured below) is not easy to see even close up. It uses a detection loop that is supposed to be suitable for bikers, but clearly from this post it is not detecting them all. Maybe it could benefit from a clear indication to cyclists of where to ride to trigger the cyclist warning sign.
Some cities use small bike symbols on the road (pictured right) to indicate where to ride to trigger traffic signals, the same approach could make this warning sign more reliable. A bike marker on the road could show cyclists where to ride to trigger the signal, I don’t know if this is a count station as well, but if it is, adding the word “counter” could encourage more cyclists to follow the marking.
Having had to go through red lights last night because there was no car around to trigger the lights I appreciate your timely advice!!
I will give it a go and see what happens. Thanks!
If you want to know a bit more about the basic science behind traffic detectors (and how to make them work for you) have a look at this article from CAN's ChainLinks magazine:
http://can.org.nz/resources/a-disturbance-in-the-force-traffic-signal-detection-of-cyclists
BTW, the Tamaki Dr detector looks like a ZELT detector, which is meant to be able to distinguish between passing motorists and cyclists. Evidently it needs a bit of tuning…
yep, pretty certain they're 3 consecutive ZELTS, I don't know whether their sensitivity changes across the loop, Glen's article says that travelling parallel to the wire gives the best reading, makes me think that a bike at either end of the diamond may be less detectable?
a summary of bike counting technology follows (I don't know how to insert a link on thos board)
http://www.nzta.govt.nz/resources/sustainable-transport/cycle-counting-in-nz/2.html
it puts a link in of its own accord, but when I tried to edit out the obvious spelling error, it just greyed out the page and returned to normal when I clicked on it
I tried this technique of riding directly along the lines of the sensor and it works! Magic!