Tuesday, December 13, 2005

Seeing the (Traffic) Light

If there's one thing that nearly every side of the transportation debate agrees upon, it's that synchronizing traffic lights is a cost-effective strategy for combatting traffic congestion. It's only one small piece of the total puzzle, of course, but it's a partial solution that offers a very high rate of return compared to adding new lanes of highway or laying new railroad track.

Bob Burke takes a look at the "traffic light synchronization" option in his story, "Seeing the (Traffic) Light."


At 2:53 PM, Blogger Ray Hyde said...

Maybe this is bass ackwards.

If the traffic lights have sensors to detect the cars and adjust themselves accordingly, then why can't we have the traffic light broadcast a signal to the cars to adjust their speed so they hit the light green? Done perfectly the cars would pass alternately, and there would be no red.

At 3:53 PM, Blogger Bob Burke said...

that sounds like the kind of application that might be out there, if they can develop the modeling to show that it would really work. they are looking, here in virginia and elsewhere, at what they can do to manage traffic demand once vehicles can send & receive data.

it's an interesting idea - that cars could gather data about road conditions and at various points it would be automatically collected and used to tweak the system. i'm intrigued by how that would all work - especially the idea that perhaps not all commuters would get the same information...

At 5:32 PM, Blogger Ray Hyde said...

Well, air traffic control can teach us a lot here.

Air traffic has no pavement to deal with, no shortage of roads, and they are three dimensional, like having stacked highways. Looking up, you seldom see airplanes close together. Yet they suffer serious congestion at some airports, because everyone wants to go the same place at the same time. Sound familiar?

29 Major US airports will reach their maximum density use within ten years, and there is no money to fix the infrastructure. They will be closed to further traffic. As it is now, if it appears that your arrival will conflict with others, your departure from home may be delayed while you are still a thousand miles away.

Localized congestion is dependent on events far away, and no amount of local control or spending will fix the problem. Sound familiar?

And the airspace is about to see a huge new influx of aircraft. Five companies are about to release lightweight 2 to six passenger business jets that sell for as little as a million dollars apiece. Businesses and air taxies will snap these things up. You may be able to charter a private jet for less than you can fly commercial, fly direct to the closest small airport, and avoid security hassles. These could add 200,000 aircraft to the active fleet in ten years. And then there are the unmanned robotic aircraft. We could see air traffic increase by 30% in ten years, and there is no present way to deal with it. Sound familiar?

Large aircraft have a Terminal Collision Avoidance System that works cooperatively with other aircraft. When the system is triggered each aircraft is assigned a collision avoidance response which the pilot follows instictively after an alarm sounds.

It took a billion dollars and fifteen years to develop, and now it is nearly obsolete. Also, it only works for aircraft that are equipped. Other aircraft are considered non-coperative and work under different rules and constraints.

But the traffic light replacement ought to be easy because it does not have to deal with a three dimensional problem. You could have a series of timed strobes arranged so that the strobes never enter the intersection at the same time.

As you approach the intersection the strobe would appear in a crosshair on you windshield. At the proper speed the strobe would appear steady. Too fast or too slow and the stobe would appear to blink or change color.

Since virtually all cars are computer controlled, it would be a small step to have the computer take over the throttle, and the strobe could be a radio signal.

Cars turning at the intersection are a different problem, and maybe they have to wait for a light, as usual.

You don't have to know the conditions everywhere, just control the intersection and merges to make a huge difference. All you have to do is eliminate the uncertainty of peoples erratic behavior.

Patent applied for

At 5:46 PM, Blogger Toomanytaxes said...

Funny thing about networks, they are only as good as their busy hour capacity. Carriers (e.g., Verizon, AT&T, Sprint) have, in addition to augmenting their network capacities, used a variety of pricing techniques to move some demand to off-peak hours. They also have the ability to institute network "chokes" to keep traffic from even entering the network in certain extreme cases. These network controls are often used in connection with mass call-in programs.

What could/should the Commonwealth and Virginia's large counties and cities do on the demand side? Some solutions might be quite a bit less expensive than merely adding capacity. What works for communications would probably work for transportation if the true goal is the efficient movement of traffic.

At 8:53 AM, Blogger Ray Hyde said...

If the goalis to get people to drive less, then charge more for drving. If the goal is to reduce congestion, then charge more for driving in congested areas. Understand ,however that these rules will probably reduce business or locate it elsewhere. Limiting housing where transportation is overtaxed is probably agood idea,as far as it goes. But the driver for cogestion is primarily the draw associated with job. There are also obvious bottle necks like reducing 66 from six lanes to two. If you want to reduce cogestion then apply the same argument against new housing where transport is overtaxed to jobs, or move the jobs elsewhere. The questioon we need to ask is how much do we want to reduce travel(and associated business) vs how much we want to reduce congestion irrespective of travel. To my mind cogestion is worse, because it is total waste. Unnecessary travel is also a waste, but now you get into value judgements.

At 12:56 PM, Blogger Toomanytaxes said...

One form of "congestion pricing" might be to tax parking spaces located in highly congested locations. Some of the money might be used to provide tax credits for businesses and other entities that met a certain measurable standard for teleworking/telecommuting.

At 4:59 PM, Blogger Ray Hyde said...

I like the idea conceptually, England does something like that, and limits the parking spaces allowed for various activities.

But if I'm a store, that you are already taxing for real estate and income, I'm going to be unhappy if you tax my customers before I even get them in the door. I might even move someplace else.


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