Traffic signals and the Idaho Stop, part 2

by John Allen

The Safety corner article in the July Wheelpeople examined i “Idaho stop” laws which permit bicyclists to yield right of way at stop signs without coming to a full stop.

Another typical provision of Idaho Stop laws permits bicyclists to treat traffic signals as if they were stop signs – that is, bicyclists may enter the intersection on red after yielding to any conflicting traffic.

I regard this provision as more troublesome than the Idaho stop for stop signs.

Why is that? A traffic-signal warrant – the official documentation which establishes that a signal is – well, warranted – must be based on data identifying a problem that stop signs cannot solve. At a crossing of a multi-lane street with heavy and fast traffic and no traffic signal, you might wait a very long time until you can find an opportunity to cross safely. A restricted sight line over a hillcrest or around a curve could prevent you from seeing the cross traffic in time to yield. In such situations, a traffic signal is warranted.

Traffic signals cause delay, and they are expensive to install and maintain. Warrants for them aren’t taken lightly.

Given these facts, why would anyone want to have a law allowing bicyclists to enter an intersection on the red? Well, actually, there are reasons, some better than others.

• Traffic signal timing must account for heavy traffic. If traffic is light, waiting for a red light can be reduced to a frustrating exercise in good citizenship.
• Often, traffic signal timing along a street is coordinated for travel at the speed limit (a “green wave”) – but bicyclists don’t travel that fast.
• Traffic signals may be triggered by sensors that detect whether a vehicle is waiting, and those may not work for bicycles. That is to say, you may never get a green light until a car comes up behind you and triggers the detector.
• Also, some people just don’t like to think that the law applies to them. Unfortunate, but true…

Better vehicle detectors do detect bicycles. There is more than one type.

• An upside-down metal detector antenna with three lengthwise wires rather than two. These concentrate the signal so that the detector can be made more sensitive without false triggering on vehicles in the next lane. This is the most common type, shown in the photo below. Ride up the middle wire. Usually, there will be a sign and a marking on the pavement indicating where to wait. There may also be diagonal wires, and that works everywhere over the pattern of wires. If there is no middle wire, position your bicycle over one of the side wires, and hope.
• Some detectors use video cameras mounted on the signal mast. You will see a cylindrical camera pointing down at you. These usually work. At night, you may have to tilt you bicycle and turn the handlebars so your headlight shines up at the camera.
• The best kind of detector, though still rare, uses LIDAR (laser image detection and ranging) – like radar except that instead of radio waves, it uses infrared light. LIDAR can determine the distance and speed of all kinds of vehicles including bicycles, as well as pedestrians.

But most vehicle detectors are still the upside-down metal detector type with no center wire and do not reliably detect bicycles. This is where the Idaho stop law attempts to fill the gap. You might call it a software solution to a hardware problem. If bicyclists may legally enter an intersection on a red light, then the problem with detection is solved, right? Well, not necessarily, as it may not always be possible, or safe. And, a special exemption for bicyclists doesn’t do anything for our community relations.

How does this affect us on our group rides? It is best to be patient. If one bicycle sitting directly over the wires doesn’t trigger the signal, more than one may. And usually, a car will come up behind. Beckon the driver to pull forward, just behind you, or the car may not trigger the signal.

Massachusetts may soon have an Idaho Stop law, thanks to efforts by Massbike and other advocacy organizations but again, the light really should change for us. The technology to make this happing exists but its use depends on funding, and politics, and with many such things, progress is slow.

[ picture in Google Drive as document, couldn't figure out how to extract it from the article, "Idaho stop 2 image" ]