…ye who enter here:
After a recent weekend where I couldn’t trigger a traffic signal for the life of me, I sat down to do a bit of research. A quick search for – traffic signals not triggered bicycle – yielded ~465,000 results. As part of this search, I found a blog by Nome Agusta detailing his court battle regarding these pesky detectors. When you have a few moments check out Post 1 and Post 2. I decided to see how tolerant my local constabulary would be in the event I ultimately gave up the wait and ran the red light. What follows is the e-mail exchange between myself, the administrative officer who first replied and a city traffic engineer that he went to for clarification. Okay, I’ll admit that deep down I was hoping they’d be a little less helpful and a little less polite; they were quick to respond and are trying to see what they can do to help. I’ve left the names of the people and streets out of this post. See what you think.
Me: I commute by bike and the majority of the traffic signals I encounter during my trip aren’t triggered by a bicycle. In that situation, is it appropriate to run the red light?
Officer: Bike riders are required to obey all traffic laws. I see your problem but I must tell you what the ordinances state. You could trip the pedestrian push button. See if that helps.
Me: Yes, it is a Catch 22. I have been doing exactly what you suggest with the pedestrian push buttons (when they are available) however that entails my having to, sometimes, jaywalk in order to get to the button. Example: Southbound [Street A] at [busy, Street B] has a left turn lane and a right turn lane — I need to turn left so am quite often left standing in the middle of three lanes (one northbound). I have to make sure no one headed west on [Street B] is going to be turning right, no one headed east on [Street B] is going to be turning left and no one headed south on [Street A] is going to be in the right hand lane so I can put the kickstand down on my bike, leave it in the center lane, jaywalk over to hit the button which, most days, immediately turns the light on [Street B] yellow and jaywalk back to my bike hoping to make it into the intersection before my signal turns yellow.
I heartily agree that bike riders must obey all traffic laws, but the design of many of our intersections prevent a cyclist’s ability to obey one law without breaking another. Can the sensitivity of the sensors be adjusted to accommodate bicycles? – and if so, who would I contact to give them a list of intersections to check out?
Sorry if this is a bit of a rant – but I want to do the right thing – and – remain safe while I’m out on the streets.
Officer: Let me ask the traffic engineers about the sensitivity issue and see what they can tell me. I will then let you know.
Two hours later I received the following:
Helpful City Traffic Engineer: Warren,
I wanted to take this opportunity to respond to your concerns regarding detection of bicycles at signalized intersections. I certainly appreciate your frustration. This is an age old problem that has plagued the traffic industry for many years. Unfortunately, there still is not a fool proof solution. We have different kinds of detection depending on the intersection. The type of detection at [Street B] and [Street A] is induction loop. This consists of a series of cable loops sawed into the actual pavement surface. We use a series of diamond loops because they are more sensitive and detect better than other forms of induction loops. However, there are still limits. Based on the technology, it will only pick up metal objects that pass through the detection zone. It is much like passing a metal rod through a coil of wire, like we used to experiment with in science class. When there is a change in the inductance field, it triggers a call to the controller. When vehicles drive over the loops, we generally never have a problem picking them up because of the mass of metal and their physical size. We do have some success picking up motorcycles, although this is not close to 100% of the time. Bicycles pose a unique challenge, especially with the graphite bikes that they are making. Even if they are the old heavy metal frames, it is almost impossible to detect them. We do have some ability to adjust the sensitivity at the control center. But when we do that, we begin to pick up vehicles in adjacent lanes. For the left turn movement, we would begin picking up vehicles in the adjacent southbound lane as well as vehicles in the northbound lane. These vehicles would be picked up and put in a call to the left turn phase even though there was not a vehicle in the left turn lane. This increases the delay unnecessarily at the intersection for every cycle.
The other type of detection we have is video detection. Unlike induction loops, there are no physical detectors in the pavement. It is based on a specific detection zone that is programmed on the screen based on the camera image. It operates by looking at the change in the pixel count on the camera image. When the pixel count changes by some defined number, a call is placed to the controller. In this type of detection, we don’t have to worry about picking up vehicles in adjacent lanes when the sensitivity is increased. The problem is that shadow images and debris can put in false calls when there are no vehicles present.
The industry recognizes these problems and is working toward ways to address the issues of bicycle detection. We do not recommend running the red light in any circumstance. What we would recommend instead is to exit the roadway at the intersections that are causing problems and access the sidewalk as a pedestrian. At that time, you can push the pedestrian button and cross the street like a pedestrian until you get to the appropriate side of the street. I know this is additional time for you and is not convenient. If you give me a list of the intersections that you currently have problems with, we will take a look at each one individually to see if we can adjust the sensitivity without causing other problems in the intersection.
My contact information is shown below.
[…and, it was.]
Since that last e-mail I have had a couple other exchanges with the HCTE and he has a crew that is checking out the intersections I’ve let him know about. In the event it doesn’t look like there is going to be a car around to help trigger the signal I need, I am exiting the road and using the crosswalk. Sure, it takes me a few extra seconds but I am always thinking that impatient drivers shouldn’t complain about the couple extra seconds my presence is costing them… In the mean time, there are other things you can try if you find yourself stuck, waiting for a light. Look for the most sensitive regions of common inductive loop patterns. You may even want to try laying you bike down across the loops.
A more detailed description of how these loops work can be found HERE.
Any other helpful hints?