Self-Adapting Traffic Lights

Roland Piquepaille writes "If you're like me, I bet you hate moments when you're in a hurry and all the traffic lights seem to intentionally switch to red just in front of your car. Now, according to Nature, a Belgian traffic researcher thinks that traffic lights that respond to local conditions could ease congestion and reduce your frustration. His method would not give you the individual power to switch the light to green. But if you were part of a group of cars approaching a red light, inexpensive traffic-flow sensors would detect your group in advance and turn the light to green. His simulations show that such adaptive traffic control is 30% more efficient than traditional ways of regulating traffic. However, his system has not been adopted by any large city. So you'll continue to be frustrated by these ?%&$! traffic lights for a while. You'll find more details and references in this overview."

Comments

Weight Sensors

[fembots]

My city has weight sensors laid under the tarmacs, so it knows if there are cars waiting/approaching and switches lights accordingly, or if it shall let the other direction keep going.

The real problem only arises when there are too many cards coming from all directions, and the lights will switch to the "traditional method" that is based on a predefined interval.

It's a catch-22 - Gershenson admits that the benefits wouldn't be as large in a big city where the situation is much more complex than in his simulations, however only bigger city needs to/will consider such traffic control.

Re:Weight Sensors

[ProfaneBaby]

In Orange County (CA), the predictive/sensor lights are already in place, and are on date/time schedules, as well.

At night, a single car coming will have the green light lit in advance assuming no other cars at the intersection.

During light traffic hours, a large group of cars will get the light over a single car, though the single car will get the light immediately after passing.

During heavy traffic hours, the light will cycle in sequence, with exceptions made for emergency vehicles.

Works reasonably well.

Re:Weight Sensors

[rawket.scientist]

will even dedict lightweight objects like motorcycles

But not, alas, bicycles. There's one redlight back at my alma mater that doesn't turn unless you trip the sensor; it was either run it, or wait half an hour for a car to show up.

Re:Weight Sensors

[Nate B.]

Well, they have the capability to detect motorcycles and bicycles, but often the street dept. lowers the sensitivity to the point that only vehicles larger than a small car are detected. This is well documented on many motorcycle discussion boards.

Often times a motorcyclist must wait until a car appears behind them to activate the sensor. Alternate action requires dismounting the bike and pressing the pedestrian button. In frustration some have waited several minutes in the hope a vehicle would appear to trip the light and when none have they finally felt safe to procede only to be stopped and written a ticket. It seems the only way to change the situation is to take it up with the street/highway dept. and/or the local government--not helpful hundreds of miles (km) from home.

Fortunately, there is only one sensor activated light in this town, but one of these days I'm going to be on a day ride and get stuck in one.

Re:Weight Sensors

[bfields]

There's one redlight back at my alma mater that doesn't turn unless you trip the sensor; it was either run it, or wait half an hour for a car to show up.

A light along my regular commute had the same problem. I emailed the city's signs & signals department. After a few exchanges, they actually sent some people out to check the adjustment and mark with spraypaint the place where I should place my bike to trip the sensor.

As it turns out, they got it wrong--I eventually figured out I needed to be in a different position.

But the point is that it's worth being persistent--people may be willing to help, and there is probably some reasonable solution.

--Bruce Fields

Re:Weight Sensors

[sylvester]

Try lining up your bike tires with one of the edges of the sensor when you pull up. Once I learned to do this I was able to reliably trip the sensor and get the light to change.

In Ottawa, Canada, the majority of lights have sensors, and the vast majority of those sensors are marked with three dots that indicate where bicycles should go to have the best chance of triggering the sensors. The sensors that have those dots are very reliably tripped.

-Rob

Traffic Lights

[AetherGoth]

When I was in San Jose, CA a couple of years back, they had a system up where sensors in the road would pick up cars at intersections. They then used microwave antennae to broadcast the information to lights further down the road. So if you were driving along at night with nobody else on the road, you would get long strings of green lights going your way.

Re:Traffic Lights

[IO ERROR]

Most traditional traffic lights are programmed to remain green for the major thoroughfare at night anyway, unless a vehicle pulls up from one of the side streets.

The city around here got creative and installed radar to determine if someone's approaching a light. On almost every light in town. That shiny radar detector is now completely useless in town...

Conspiracy Theory

[acomj]

Maybe, just maybe

Thet aren't out to get you, but in fact they screwed up the installation.

I've done a lot of construction and can see how this might happen, they screw things up all the time when they build things ..

You should contact whoever is responsible for the road a mention this.

Not a chance

[LanceUppercut]

US is currently preparing for a completely different thing - a more or less massive roll-out of red-light cameras (the thing where you get you car's photograph in the mail and a red-light ticket). As a preparation for this measure, stop lights are adjusted (most of the time the duration of yellow is simply reduced) in order to increase you chances of running red light, thus increasing the profit generated by red-light tickets. (This will also increase the fatality rate, of course, but this doesn't seem to be a reason for concern.) I'm amazed how much more often these days in California I see cars crossing intersection right under my nose even when I have green. A couple of years ago I'd see something like this about once in a month. These days I see it virtually every day. In this evironment it is highly unlikely (read - impossible) that US authorities will implement anything tha will to decrease your chances of running red light. Today they prefer to make money by decresing public safety, not by increasing it. So you can forget about anything like "driver friendly" stop light for a while.