Alabama Gazette - The people's voice of reason

More Traffic Signal Solutions

 


Last month I described how the Finnline and adequate yellow time can put an end to dangerous panic stops at signaled intersections. Here are some additional remedies to improve the traffic flow.

The legitimacy of installing a signal for a private property is dubious at best. And because of the way many are timed, they are particularly obnoxious.

A few weeks ago, Walmart opened a new store on highway 231 across from the Garrett Coliseum in Montgomery. Like at every other I had seen, it had a signal installed at its entrance. Because it—like many of the others—trips immediately as soon as one vehicle pulls up to the exit, it can pile up as many as 40 or 50 on the highway every minute or two.

One solution is to prohibit installing signals for private properties. If that should prove impractical, they could at least be timed so the green lights on the highways do not change immediately—they would change only after at least 30 seconds have passed. That would allow several cars to accumulate at an exit and pass through each time a signal is tripped. As soon as the exiting traffic has passed, the light would change and remain green on the highway for no less than two minutes before turning red again. The stops on the highway, for a typical time period, would be reduced three or four fold. The highway’s capacity and flow would be greatly increased.

This same strategy should be applied at every intersection along highways and major arteries. Some lights are already timed in this manner, but there are many that trip immediately.

At any signaled intersection, the green light should always default on the highway. The light should never change unless it is tripped. And unless cars continue to pass over the tripping device during each cycle, the green on the side road and the red on the highway should be minimal—no more than 30 seconds.

There are many highways that have signals that spontaneously turn red and stop traffic when absolutely nothing comes along to trip them. And often, the lights remain red for one or two minutes while dozens of angry motorists sit and watch nothing but the wind cross the highway. These abominations should be eliminated immediately.

Protected left turns can also be nightmares. For starters, there are far too many of them. The only time a protected left turn is desirable is when a substantial amount of the traffic flow actually turns left—25% at the very least. I can’t even count the numerous intersections along major highways that have protected left turns for miniscule side roads that have almost no traffic. This enables a single car to pile up dozens of others coming from the opposite direction. In addition, the protected left turn often stays green long after the last car has passed over the left turn sensor, long enough for eight or ten cars when perhaps one or two, and often none, actually turn left. Eventually, the backed up traffic on the highway gets a green light.

There are two types of protected left turns. The more desirable turns from a green arrow to circular green, which allows people to continue to make left turns as long as the oncoming traffic has cleared. The other, undesirable type changes from a green arrow to red. If someone is waiting at one of these, he has to sit and wait for the light cycle. A dozen or more cars coming the other way must also stop and wait before they can proceed. When this is multiplied by numerous similar signals, traffic flow suffers.

There are many intersections that need signals for only a few peak hours each workday and none at all on weekends and holidays. A very simple way to improve the flow is to program these signals to go into flash mode during all non-peak hours—yellow on the highways and red on the side roads. This is already practiced on a few inner city streets and highways during late night and early morning hours, but these hours could be greatly expanded and extended to the outlying and rural areas.

And finally, there are some intersections that should just not have signals, period. The street and highway departments are reluctant to disclose the criteria that are applied to warrant a signal, but from my own experience, I have observed numerous intersections that would be better off without them, but not even a single one that did not have a signal but needed one. As usual, our overgrown government agencies tend to over-regulate almost always and under-regulate almost never. We need to turn that trend around.

 

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