I appreciate the insight into intersection controls, but ask the question: why try to facilitate traffic rather than looking for ways to dimiish the number of automobiles on the road. To make intersections efficient is to further institutionalize roadbuilding and encourage sprawl. It is the very inefficiency of individual transit as a system, in economic, functional and environmental terms, that has proven its inefficacy as infrastructure. Let's reinvent cities rather than propping up a largely discredited transit modality.
Gary R. Collins, AIA
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Original Message:
Sent: 01-06-2014 20:05
From: Patrick Baechle
Subject: Why traffic signals have many bad outcomes for urbanity
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Patrick Baechle AIA
Firm Owner/Architect
Baechle & Associates
Hollidaysburg PA
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Original Message:
Sent: 01-06-2014 18:37
From: Nikolaus Philipsen
Subject: Why traffic signals have many bad outcomes for urbanity
This message has been cross posted to the following Discussion Forums: Committee on the Environment and Regional and Urban Design Committee .
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I've had this idea for quite awhile. I believe that it is possible to conserve billions of barrels of oil and reduce carbon dioxide emissions dramatically by creating and implementing one simple invention. We need to develop smart traffic lights, which sense the momentum of vehicles and make intelligent, energy conservative decisions about traffic flow. These sensing devices need to replace the current system of timers, which cause vehicles to stop and idle when no cross traffic is present.
I assume that this technology is already be installed in dense urban environments where sophisticated traffic control systems are in place. That is good, but, I suggest that this technology be further developed and installed on every single traffic light in the United States. You may think that is impractical, but answer this question. How many times have you been out in the middle of the country, sitting at a traffic light, burning fuel, waiting patiently for the light to change when no other vehicles were present?
On a regular basis, I am often get trapped at one particular traffic light where 6 or 7 vehicles all need to come to a complete stop and wait for one car to pass thru. Sitting there waiting, I have thought about the fact that 6 vehicles, traveling at 40 MPH have just lost all of their momentum and now must restart and gain all of that momentum back. How much fuel is being wasted at every traffic light in the country where the same thing happens day after day? This has got to be one of the most wasteful and inefficient use of fuel throughout the nation. If only the traffic light stayed green for another 20 seconds. What harm could there be in that.
I was not a star physics student, but I remember one important thing. It takes a lot more energy to move a body from a dead stop then it does to travel the same distance already in motion. If the traffic light computer could sense the momentum of the vehicles traveling toward it, then it could calculate that more energy would be conserved by leaving the green light on for 20 more seconds rather than by letting the idling vehicle move through.
First we would need a sensor to identify the number of vehicles, their speed and their mass, and then we would need a computer program to determine the most efficient timing of the traffic signal. I believe we already have the technology to produce this type of sensing device. There are a number of ways to sense vehicles in motion: infra-red heat sensors; ultra sonic motion sensors; mechanical, pneumatic or electronic sensors built into roadways; microwave sensors; video sensors or simple visible light beam sensors. This sensing device would be used in combination with a computer module. This program would make a decision to change the stop light based on the data it receives from the sensors. For example:
If the computer senses that 500 feet away, there are 5 cars in motion and there are 10 cars sitting idle at the cross road, it could decide to leave the green light on a little longer, or let the stopped traffic flow through. In simple terms, the computer is determining, roughly and quickly, how much energy will be used to stop and restart the momentum of moving vehicles, vs. how much is being used by the idling vehicles. If momentum wins, the light changes in favor of that traffic flow using the lesser amount of energy. If the computer instantly determines that ten idling vehicles will use more energy than would be required to restart 5 vehicles then of course it changes the light to allow the stopped idling vehicles to proceed. (The computer is not actually calculating energy use of each vehicle, but simply making calculations based on pre-set statistical data attached to vehicle mass)
The whole idea is to keep traffic continually flowing and to keep vehicles operating at their highest efficiency. There would be no compromise in safety, because traffic lights would still change as usual, although not regularly, or repetitively as they do now. Yes, there may be some disgruntled drivers who now and then have to wait longer at a light, but, overall, this system would actually reduce waiting times for everyone. I would even go so far to suggest that the speed of vehicular travel in America would increase dramatically, creating all kinds of positive economic ripple effects, from faster deliveries to more efficient use of time for everyone. Without a doubt these devices could reduce carbon emissions substantially.
I am not suggesting that this concept will relieve congestion and work effectively in dense urban areas. These problems are already being addressed. I believe we need to look at how much oil could be conserved by adding up the energy lost daily at every small town intersection, country crossroad and common collector street throughout the nation. There must be millions of traffic lights in the United States. If each one was required to be fit with an energy momentum sensor the benefits would be huge.
I believe that a policy should be enacted to require every single traffic light in the U.S. to be retrofitted with a vehicular momentum sensing traffic light control.
- Research, development and installation of these devices would create jobs.
- The speed of business could pick up across the entire nation
- This project would significantly reduce our dependence on foreign oil.
- This project would significantly reduce carbon emissions into the environment.
- This project would extend our national oil reserves through daily energy conservation savings
This idea does not involve rocket science. It is very simple technology. There could be a national competition to design the most effective and economical devices. This does not involve replacing traffic lights; only the timing devices would be replaced. Motion sensors could be mounted on existing utility poles or cables as they are now. It must be required to have this system installed on each and every single traffic light in the entire country to be effective. A lot of communities will moan and groan about the cost of doing it (although minor), but let's face it; we waste a lot of money on less beneficial things.