Traffic Lights – Time Wasters for All!

April 12th, 2008

I few months ago my route to work changed and now includes about a dozen traffic lights. I used to have to commute 90+ minutes down toward Boston in traffic but since my office has moved I now have the option of taking a more rural route. I’m not complaining.. it’s a huge improvement over the traffic and truth be told I could still cover most of my current commute on highways if I wanted to. It’s not that I’m unhappy with the lights, it’s just that I think they could be programmed to work more efficiently. Let me also preface this by mentioning that all of these observations are likely null and void in a more urban area where traffic is ubiquitous. This is based on my ride to work through a more suburban area that is not wall to wall cars. I’m not talking about a very high car density.

Traffic lights around here, and I imagine in a good may places, base their logic on sensors embedded in the pavement that run about 20′ feet from the white line back. The distance seems to vary based on how much traffic they expect to see at any given line. For instance a side road may only sense 10 feet back but a more major road will have a line 40 feet back. All these sensors do is tell the system that a vehicle is there. Not too bright. This is a problem because the system isn’t smart enough to sense what is coming down the road. How many times have you been driving along in a long group of 20 or 30 cars and have to stop at every single light to let one person cross over the road? It’s inefficient as well as wasteful. Stopping and starting 30 cars 5 times is much more expensive then holding one car for another 15 seconds at 5 lights.

The road system should have some way to figure out when it makes sense to hold a car and when it makes sense to change the lights. I think we need to replace the traffic light sensors with a camera system that can detect what is happening on the road system. It should then use that data to calculate the ‘wait seconds’ for each light. For instance, you are sitting in your car at a red light. For every second that passes the system would count one ‘wait second’. If there is a car behind you the system adds 2 ‘wait seconds’ per second and so on. Each car waiting is counted as one ‘wait second’. In a column of 30 cars each second that passes that the system would count 30 ‘wait seconds’ one ‘wait second’ per second for each vehicle waiting. It could then use that information against what is happening at the other points of the intersection to figure out how to best reduce wait times for people.

Ideally it would also be able to either pull data from other traffic lights along the road or have some way to detect oncoming traffic from a good distance away. With all this falling into place it should be possible to increase the number of green lights a long column of cars sees when traveling down a road.

The other option it seems would be to switch the logic on these light off during non-peak times. During the morning commute lots of cars are coming from all directions and without and guidance you would end up with long lines of waiting cars. In these cases lights work out well. They allow time for each direction of traffic to pass and keep the lines down. During off peak times you may pull up to a red light and have to wait for a light cycle to happen simply because the system defaults to letting one road get green when no cars are waiting. You have to wait even if no cars are coming. If they switched the lights to flashing yellow during off peak times the major road could always keep moving the side roads could go as needed and not have to wait for a green light.

The obvious flaw in this plan is the American driver. As a general rule if there is enough space for you to pull out and not get hit by oncoming traffic… the average American will. Even if you are the only car on the road they will pull out and make you slam on your brakes to save themselves a fraction of a second of waiting. If we switch to the flashing yellow I’m sure the same will happen and the idealistic plan will fall apart, which is too bad. The joys of selfishness…

So! What conclusions have we drawn thus far? I sit at enough red lights waiting to think this crap up… And I wish I didn’t need to wait so long. Great. Class dismissed!

Topslakr

Trackback URI | Comments RSS

Leave a Reply