Commuting - A Letter About Traffic Signal Sensors

I am planning on writing a letter to my borough about the failure of a traffic signal sensor along my commute route to pick up my bicycle and change the light to green. I have sat for up to 2 inutes and 30 seconds waiting for a car to come up behind me to change the light for me. I have also dismounted and hit the ped button to change it, tried lying my bike down on the sensor which doesn't work, and run the red light when it wouldn't change. But it is time for the borough to receieve notice about the situation.

I'm not a traffic engineer or signal maker, so I don't know any good details to throw at them. Can anyone help with specifics for this type of letter?

John Allen has written an interesting article on the subject. Here it is:

http://www.bikexprt.com/bicycle/actuator.htm

It just depends, here in Queensland it's possible to wait 2 minutes and 30 seconds (I timed a set of lights in Brisbane at 10 minutes a few weeks back) after a car has arrived. Could it be that the light is just plain slow.

How 'bout:


Pennsylvania law defines a bicycle as a vehicle. Several traffic signals in this borough, however, are designed only to accomodate certain types of vehicle, that is, only those with sufficient metal to trigger them. Does this mean that only those vehicles with sufficient metal to trigger these signals are required to abide by them? A reasonable person would presume otherwise. This is not in keepng with state (or is it Commonwealth?) law that treats vehicles, regardless metal content, equally. I hereby request that you dismantle all signal mechanisms that fail to treat all vehicles, as defined by state law, equally.

Make it a petition (not an official one, but just to show that there are a number of people requesting it.

A few years back Portland tested many of their loop detectors for sensitivity and placed a bicycle stencil at the most sensitive portions of the loops, in order for bicyclists to know where to stop their bikes to trigger the loops. Unfortunately, most of the stencils have by now worn off and have not been replaced. Nevertheless, in most cases, the outer periphery of the loops are the most sensitive, so if you can see the outline of the detector by locating where the asphalt has been sealed after the detector was installed that's where to be with your bike - either on or near the corner of the diamond or near or just inside the circumference of the circle, depending on the shape of the loop. It is possible that the detectors still won't be sensitive enough for a bike, especially if there's a lot of aluminum in your ride (when I was first starting to drive, I remember loop detectors in my home town that wouldn't register a '71 VW microbus, let alone a bicycle), but these days most detectors are pretty sensitive, and getting the bottom bracket of your aluminum bike near the most sensitive part of the detector is probably your best bet. Or pull up far enough so the car behind you will trigger the detector...Good luck!

Tennessee passed a law in the last year or so, that allows motorcycles to treat these as a stop sign. I don't see any reason not to do the same when on a bicycle.
BTW, the cops in my town told me to do this, and gave me a look like I was an idiot for even having to ask such a question. :(

I find that my aluminum bikes do not trip the sensors. Since aluminum is not magnetic, I don't expect them to do so unless the sensor happens to trip off of the various steel fasteners.

A traffic light that will not trigger off a bike is simply defective and to be treated as such. Just wait until it is safe and proceed through the intersection. No reason to have to wait for an automotive escort.

...
and getting the bottom bracket of your aluminum bike near the most sensitive part of the detector is probably your best bet. Or pull up far enough so the car behind you will trigger the detector...

I do somehthing similar. I go to the part of the sensor nearest the crosswalk and about in the center. Then I put my right foot on the ground and lean the whole frame over to the right, holding it with up my left hand on the handlebar grip, so that it is just inches off the ground. When the sensor trips, I pull the bike up and pedal on.

Dan

There's this one sensor at a major 7-lane intersection that I cross, located at a MARTA rail station. The light is a very long wait. But apparently, the light is set to activate within moments after a pedestrian presses the "walk" button. I love to ride up to the long line of waiting motorists and press the button.

They love me (don't they?)

:love:

Unfortunately, most traffic lights are not that convenient.

Thanks for all the input, I'll put it to good use and let you all know if anything comes of it when I send my letter. just to quick respond to a few items: I don't think my intersection is programmed for a long wait because it changes rather quickly whenever a car arrives. And I have some misgivings about running the red light, as it will just be another example of the drivers getting bad feelings about me as a cyclist within a situation they don't understand. And I like the petition idea, I even have 1 other person who I recently discovered living near me (contacted through my blog) that wants to start riding to his comm college classes a few days a week across town and asked for my route, etc, and I hope we get together to ride it soon, so with him one board it can be more than just myself petitioning!

...I don't think my intersection is programmed for a long wait because it changes rather quickly whenever a car arrives.
You can bet that if a light wasn't responding to motorists, there'd be someone out there in a few hours fixing it.

I'm not too sure, but I believe that the detectors work on an induction loop basis so they are triggered by any metal which conducts electricity.

In my home town, I complained about a particular junction to the UTC dept (Urban Traffic Control) and they were apparently able to alter the sensitivity of the detectors - end of problem

They must detect Al because I can show you one that is a signal to stop traffic and allow a right turn. If I cross it at 18 mph the light will be green by the time I hit the signal every time. The real problem I have is the left turns, If you have no way to stop traffic on a busy intersection, you can wait for long times.

One of the sensors on my route doesn't detect bicycles. Here's the kicker. The only reason bikes have to go through the intersection is that the city has "temporarily" closed part of the bike path to build a freeway exit over it.

Today, I sent an e-mail to my "neighborhood liaison" in the city. I'll post again if anything changes.

I have sat for up to 2 inutes and 30 seconds waiting for a car to come up behind me to change the light for me?

Sometimes when I'm waiting at a light and not tripping the sensor, the driver coming from behind thinks he is being considerate by staying back and giving me a lot of space. Of course, he doesn't trip the sensor either! Some of these drivers give me strange looks when I motion for them to move closer :)

Another problem with these sensors is that the minute the last car crosses them, the light changes real fast. So fast that if you're not right behind the last car, you basically pass the light in the red!

My town is installing them because the motorists have claimed the lights are red too long. As a result, the lights will now be green alot longer so you can bet there will be more accidents and deaths as a result of increased speed!

My town is installing them because the motorists have claimed the lights are red too long. As a result, the lights will now be green alot longer so you can bet there will be more accidents and deaths as a result of increased speed!

I'm not totally sure how this works. If lights change on a cycle (no pun intended), and that cycle progresses faster, surely the red changing sooner will also result in the green changing sooner. Or am I missing something here?

Either way, I do wish they would do something about the extraordinary delays we get here in Queensland. I've timed some lights in the 10-20 minute range -- and that's after a car has landed on the "sensor"!

In Minneapolis and St Paul proper most of the lights are timed, but out in the suburbs they use sensors and they aren't all created equal, some I can triger some I can't. There doesn't seem to be any consistency.

Perhaps this will show my true brain capacity! I live in Ireland and I was under the assumption that these devices were activated by mass/weight. You see one day I was at a quiet juniction and noticed the lights were not changing at their regular interval (not changing at all infact). Being a logically minded chap I went about determining what would trigger the light change. At first I was looking for some optically triggered beem. Tests showed this was not the case. After some time, the method of approaching the 'patch' at speed and breaking fast produced a change in the lights. I figured the extra force exerted equated to a greater mass and so I formed my opinion. This method has worked for me ever since. I never thought to question it!

I now wonder if my theory was correct at all? Perhaps our version is a weight system or perhaps I have been dwelling in my own little unpopulated world for too long now! I shall endevour to extract this information from the relevant body to put my mind at rest. It won't be easy but the truth must prevail :o

If it is indeed a case that the Irish employed method is also an induction loop could anyone explain why a heavy brake would trigger the change? I mean the only change in angle would be in one plain, i.e. the top tube's angle to the ground. This would bring the bike fractionally closer to the ground but to no meaningful extent surely?

Any ideas?