Sand Glass traffic light concept

Looks very interesting, but as pointed out it would be a problem for colorblind drivers unless you maintained the stack of three.

U. S. Department of Transportation adopted the Manual On Uniform Traffic Control Devices (23 USCA §§ 109(d), 114(a), 217, 315, and 402(a); 22 CFR 655, and 49 CFR 1. 48 (b)(8), 1. 48 (b)(33), and 1. 48(c)(2)). This manual contains a specific standard relating to yellow change clearance intervals. Section 4 D. 10 establishes the standard as: "a yellow signal indication must be displayed following every circular green or green arrow signal indication. The exclusive function of the yellow change interval is to warn traffic of an impending change in the right of way assignment. The duration of yellow change interval must be predetermined. " The manual specifies that a standard is a statement of required, mandatory, or specifically prohibited practice regarding a traffic control device.

The manual contains guidance in connection with this standard. The guidance specifies a yellow change interval should have a duration of approximately three to six seconds and that the longer intervals should be reserved for higher speed approaches. A guidance is a statement of recommended, but not mandatory, practice, in typical situations, with deviations allowed if engineering judgment or engineering study indicates the deviation to be appropriate.

That is a terrible idea. Looks just like a drag racing tree to me!

The only thing that keeps cross traffic accidents down to a minimum is the slow reaction time of aarpers' to a green light![/sarcasm}

Are you telling me you never look at the cross traffics lights to see if they are turning yellow so you can be ready to go?

Saw this in Germany about 3 months ago - acount down system, slightly different than hour glass shape.

I agree with bilson, plus adding the hardly ever used due to overcongestion .. an all sides red period.

Sorry. You'll just have to hone your concentration & eye/foot coordination to blast off at the first chance.

you won't get there any sooner than just waiting for the light to change,...... and I am color blind

I have to agree with onestep.....just a modified drag tree. No, I really don't try to look at the cross traffic lights.......Just not in that big a hurry!!

Or I can use the count up to cross the white line at max speed just as it changes to green.

ignore

What gets me is that they liked it enough to put it on their site with an endorsement.

Not a bad idea, but I would rather see funds going to more warning devices of a red, or soon to be red, traffic control device ahead.

Ron

I'm not a fan of re-designing the traffic light system. How about a simple improvement to the existing lights?
When lights are replaced with LED lights, the yellow light should show numerals for a 5-second countdown to the red.

You never know how long a yellow light will stay yellow, and it sure seems that some are quicker than others.

I have to agree with you there as some yellow's seem much quicker than others. I wonder if some of the quicker yellows are in any way tied into those traffic control devices which also sport a red light violation cameras....

Ron

Each light, the red, yellow and the green is variable on how long they are lit. The amount of time for the red and green usually are varied by several different factors. Some of the factors include the time of day, road type, day of the week, the number of lanes and the number of vehicles waiting at cross streets. Some recent changes being implemented include clearing or all red times, priority traffic requests and pedestrian crossing requests.

Compounding the problem with setting the timing on signals are antiquated controllers. Some of the traffic controllers sitting on street corners are more than 15 years old and they just can't handle the new equipment to run the signals more efficiently. Tie this problem with outdated central systems that can't use modern communications protocols to talk to the controller. Some of these are still 1980's dial-up speeds of 4800 to 9600 baud.

Yellow light durations are normally set according to a complicated formula that takes into account the posted speed for the road, the number of lanes, traffic volume, road slope along with local requirements. The problem with laws specifying a minimum time for a yellow is they don't take into account that every intersection is different and the time specified in the law may be way wrong for the actual conditions.

We hear a lot about the 1 second per 10 MPH rule, but that is just a generalization that doesn't take the other factors into account. If you want to play traffic engineer and set the duration of a yellow light try determining the yellow duration for a 6 lane road with a 14 foot median and a 4 lane cross street. each has dedicated left turn lanes. The main road speed is posted at 45 with the cross street at 35. The cross street is a feeder road between a housing development and a major regional shopping district. The main road is off an Interstate. Now the question is what is the optimal yellow light time for the main street and should the yellow light timing be the same for the cross street?

That's a relatively easy problem! Now throw in some more details;
sodium street lights that emit a yellow light very similar to the traffic light,
advertising signs, most always red, that are identical in colour to the traffic light,
vegetation that obscures the line of sight,
positioning of lights, sometimes they are at the far-side of the intersection, sometimes at the near-side,
innumerable street-signs, both overhead and mounted on the curbs, that further distract drivers,

It does get more and more difficult.

That is just you getting older!

Don't forget the strobes from speed/redlight cameras and no left lights.