Idea for government: Traffic Light Timers
 

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?

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.

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

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.

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 :o. Just make sure there are no hidden centre meridians under the snow! :D.

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

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

Indy
 

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

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.

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

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 :p 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 :D 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) :p

Sensor Pads
 

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

I wonder... maybe someone should design 'runway lights' at the curbs of the road where if you follow the light as it travels down the road, you'll always hit a green-lighted intersection.

Sort of like movie theatre stairway lights, only the lights would 'travel' down the road.

Ah, heck. Let's just go all out and get conveyor belted roads. Like the Jetsons' sidewalks.

That - would be totally awesome :thumbup: Actually, I've seen something sorta like that (for a different purpose). Somewhere in S. Florida - there's a 90 degree turn at the end of a highway offramp. There's an optical sensor and light up road reflectors that follow a curve... It looks really cool - and effective as the concrete at the end of the raised offramp has been "used" a few times...

Hrmm... giving it a few more instances of thought... I'm not quite sure how to program that without being confusing given that the speed needs to change for vehicles behind you...

I'm not sure what you are getting at... there's a window of time for a green light, so a motorist would need to know the maximum speed (it would be an MIN(speedlimit, maxspeed) - so as to not cause speeding), so that they could go up to that speed before they will hit the red light before it changes. The motorist would also need to know the minimum speed so that they made sure not to coast too much and go under that speed limit, missing the light.

At the moment the motorist faces a quandry - go the full speed and hit the red light, or go slower and maybe miss the green light before you get there. As it stands, sometimes I go too slow because I don't want to waste kinetic energy unecessarily, and if I don't make the light, I end up causing someone else to waste their fuel idling.

If given both speeds, the motorist can judge it himself.

Timers would be nice. Posted right on top of the light where they put the cameras but I think that education is the key. Like the website with the traffic waves. Not to get the thread to OT but how many people still speed by you as your coasting to a red light that has been red for a long time just to slam on the brakes. People just don't pay any attention to what's going on around them. All the info in the world to the driver(which is most) that doesn't understand about kinetic energy and it's affect on FE is lost.

Posted a new thread related to this one: Technique quandary: gliding toward a stale green light

I'm not sure if people are understanding the idea. The traffic light timers are well before the lights, probably just after the previous intersection or on top of a blind corner/hill. And they would be a min speed/max speed indicator. This gives a constant speed range at that point, which if they stay in, they are guaranteed to make the green light. Since there are an infinite number of such ranges, only the range with the largest values are used.

So you have:
Min speed/Max Speed Indicator <---> several hundred metres <->traffic lights

While that idea makes sense, it could create the problem of changing the light for someone who wants to turn right, which (in the US in many places) is a legal turn to make on red. In the case of small roads merging with larger roads with more traffic it might have the effect of stopping the larger flow of traffic to make little difference for the right on redder...

I hope this comment makes sense. If I could animate some gifs I would do something worthwhile. :)

Some places in LA have something similar in that there will be several blocks of lights that tend to all go on and off nearly simultaneously. The crosswalk countdown can be used to figure when to get on and off the gas.

Schultz here, I lived in Europe for four years, Bremen, W. Germ., and they already were using a form of light timers. It is (was?) illegal to idle your "auto" for more than twenty seconds at a time. If you were coming to a green light , The light would flash for five seconds before going to red. That gave you (the driver, the one on the pedal, the one presumably with the intelligence to make a decision) time to choose your course of action. Speed up? Slow down? Your choice. If you chose to stop, the government expected you to turn your engine off. When the red was ten seconds from ending the light would begin flashing again so you could start your car. And they inspected your car for emissions as well as safety, during the inspection they also tested your ability to start easily. All was covered by G. regulations. I am sure a similar program would work here. It will all fall into place when fuel is > $5 a gallon. S.

That would probably work well within the existing infrastructure. I like the idea of the fines for idling.

It has been quite a while since i was in Germ. (the army paid my way back then) But at the time people were just starting to become aware of the need for ecofriendly habits ([U]All habits). i don't remember any drive through of any kind. Some Friends who have just come back from overseas said they still don't do drive throughs. Does anyone want to do the math and see how much fuel we could save just with that one change? i am not sure my brain could handle the strain.S.

Let's use the following constants: Fuel (U.S.) is $3.00/gal over the next year, drive-thru consumption is 1.0 gal/hour (going heavy on this one since you may have to accelerate slighty to move in the line), and the wait time is 4-minutes.

1.0/60 = 0.017 gal/minute x 4 minutes = 0.067 gal
Assuming that drive-thru's are used once a week (on average), that's an extra

3.47 gallons or $10.40 used per year

Here's where it gets interesting... Let say you hit the drive-thru 3x/week:

0.067 gal x 3 days x 52 weeks =

10.45 gal or $31.35 / year.

YMMV, but it starts to add up...

Every little bit helps... same with idling at long lights.

RH77

There's be no problem (technically) if there was a downward slope on the drive-through. That way you could just turn the car off, stick it in neutral, and use the hand brake to stop.

Seeing that this is more about social engineering than engineering, you'd need to ban drive-throughs if we are stuck with our 20 year or so supply of non-hybrid (mild or otherwise) used cars.

:eek: Holy cow. Now just consider the sheer number of vehicles on the road using a drive through [U]every day[U]. what a frigging high amount of fuel the entire North American continent could save. :D makes my brain hurt. Thanx for the math.S.

Waaa! But I want my air conditioning... Waaa!

Berkeley has a ban on drive throughs IIRC... I believe that is one of the reasons why there's a ton of fast mom/pop restaurants that moved in. Especially right across from the Berkeley campus :thumbup:

:confused:Alright Treb. You pickin on grocery getters, who presumably won't leave their vehicles for twenty seconds due to the loss of A/C? OR You directly looking at me cause I live in the heat belt and desire to get to work relatively sweat free? Any ways, off topic.
on topic. I would rather see all drive through gone. The loss of fuel just sitting their idling by for a Big Mac just drives me insane. :cool:

^^ No no :p Just giving a reason why people wouldn't turn their cars off - even if they could just coast down a ramp :p

I'm in S. Florida -- heat sucks... Having to use a/c sucks even more :p Alas, I do - just don't tell anyone (need to keep up appearances and such :D).

I second the motion to remove drive throughs :D

we have "Prepare to stop when flashing" lights at many intersections in my area. A lot of people don't get them, but I think they are great. They are primarily at intersections where deaths often occur due to traffic light infractions.

I love those. I start slowing down and my mom says "WHAT ARE YOU DOING!?!? IT'S GREEN!!!! I said, stopping. it's gonna change in 3... 2... 1... red.

I had a discussion with a traffic camera guy recently. The modern intersections use video cameras to detect vehicle presence and amount of vehicles. They adjust timing accordingly to try to keep traffic flowing. This eliminates the need for sensors in the street. The sequence gets messed up when you have people racing light to light.