Idea for government: Traffic Light Timers

[newtonsfirstlaw]

Everyone has been in the situation where they are about 500m from a green (or red) traffic light and you need to guess what state the traffic light will be in by the time you reach the light. This gives you a chance to either brake early, accelerate or maintain speed so as to waste the least amount of kinetic energy your car has.

If traffic light timers were installed at lights, and on blind corners or hills, unnecessary stops could be virtually eliminated. Particularly on the latter, an easy calculation could be made to show you the minimum and maximum speed you'd need to maintain to reach the light in time.

There would be quirks involved - often pressure sensors are used to stop for side roads, and ambulances can send a radio signal to get a green light. There are also pedestrian crossing buttons to consider. Obviously the ambulances should have priority, meaning that there has to be a margin of safety associated with these speeds - they should be within the speed limit, and have the light turn green maybe 70m or so before traffic is scheduled to show up, so that they can brake in time for the light changed as a result of the ambulance.

The pressure sensors and traffic crossing buttons would have to result in a scheduled light change being delayed so that the traffic heading towards the lights would not be fooled. Usually in these instances it is one vehicle stopping traffic for 10 or 20 vehicles, resulting in huge wastes of energy.

Tested in a small city, I suspect that this would remove the need to rush for most people - only the really stupid people would race to the red lights, and everyone else would cruise or coast.

Thoughts?

[Peakster]

I've actually seen timers in some cities (Edmonton's 82nd Avenue comes to mind) where the flashing 'stop hand' for pedestrians counts down numerically to when it's a solid stop hand (and thus the intersection's traffic light turns yellow).

I agree that timers like those would be very beneficial at all traffic-light controlled intersections. Especially for roads with higher posted speed limits.

[newtonsfirstlaw]

Originally Posted by Peakster

Especially for roads with higher posted speed limits.

Good point - it's here where most kinetic energy is lost.

[MetroMPG]

The city I live in has been installing countdown "walk" signals at new intersections in recent years - even the ones that are always green for through traffic in the absense of a cross-traffic vehicle activating a sensor.

I've also seen a road in another city where signal timing was used as a means to control speed: signs were posted saying, "Green signals timed for 40 km/h". Brilliant!

Peakster: don't the lights on the ring road around the Peg have a set of flashers upstream that warn you of an impending change? I seem to recall them on certain sections of the Trans Canada where there are lights occasionally stopping a flow of traffic going 100+ km/h.

[Peakster]

Originally Posted by MetroMPG

Peakster: don't the lights on the ring road around the Peg have a set of flashers upstream that warn you of an impending change? I seem to recall them on certain sections of the Trans Canada where there are lights occasionally stopping a flow of traffic going 100+ km/h.

You are correct. They have amber flashing lights for (if I recall correctly) four at-grade intersections for the southern bypass for Trans-Canada traffic around Winnipeg. I sometimes just take a right turn at the stoplight, make a U-turn on the intersecting road, and get right back on the highway . Just make sure there are no hidden centre meridians under the snow! .

What were you up to driving in Western Canada, MetroMPG? That's kind of far from where you live.

[MetroMPG]

I had relatives in Winnipeg for a while. And I've gone to B.C. and back by car a few times.

[RH77]

I've noticed that many Indianapolis downtown lights are timed to 35 mph. It's great -- if you get into the street and interpret the current pattern, it's a seamless flow.

Most folks like to "Accelerate and Pile-Up", though. It's supposed to keep speeders at bay, but the accel-a-holics have a field day.

RH77

[newtonsfirstlaw]

Originally Posted by Peakster

sometimes just take a right turn at the stoplight, make a U-turn on the intersecting road, and get right back on the highway . Just make sure there are no hidden centre meridians under the snow! .

And I thought I was the only person who has ever done this. It allows you to still maintain some momentum, which is an advantage over turning the ignition off and waiting at the lights.

[trebuchet03]

Just FYI... Most road sensors are inductive sensors as opposed to pressure sensors Which is why bicycles might not trigger them

I've noticed in Orlando that there's two sets of road sensors... One about 50-100 yards from the light, and another set at the light itself... I don't know if they're using it to figure out when traffic is coming, or when the light has backed up cars up to that point But they're only in the heavily used roads...

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Rather than tell people how long they have to hit a green (resulting in people laying down on the gas)... Tell them how fast they need to go to hit a green A buddy of mine was telling me about a system just like that in Poland. The speed sign (not necessarily limit) starts at some speed and will go up/down as time passes to ensure you get a green. Apparently, your idle time goes down to near zero (unless you need to make a turn across the other right of way)

[RH77]

Originally Posted by trebuchet03

I've noticed in Orlando that there's two sets of road sensors... One about 50-100 yards from the light, and another set at the light itself... I don't know if they're using it to figure out when traffic is coming, or when the light has backed up cars up to that point But they're only in the heavily used roads...

We have the same here, with roads that have speed limits from 60-70 and traffic lights. Of 3 sensors, I think the first 2 sensors calculate the "Yellow-Duration" based on speed of the approaching high-speed traffic (based on the constant of distance between the pads and the trigger of the vehicle passing each). The final pad probably detects if the vehicle has stopped and is waiting, and also the final calculation for the "Yellow-Duration" if the vehicle has not slowed. Many times, I've hit that first pad and the light has turned yellow (if I continue, the yellow holds until I clear the intersection -- if I slow to stop, the red is triggered sooner).

Local observations...

RH77