What is the federal law on the time length of a yellow light?

Question

what is the federal law on the time length of a yellow light?

Answer 1

I don't think there is a Federal standard on this.  Individual cities are free to adjust the length of signal lights to the needs of their traffic situation...  It's been my experience that intersections with red light cameras seem to have shorter yellows than those without the automated income generators.

Answer 2

None, Zero, Nada.......what ever the city and state decide is what time length will be..

Answer 3

Personally, I know the law as being a minimum of 3 seconds, but a lot of cities increase it to about 6 seconds for safety reasons.

Answer 4

Believe it is 4 seconds

Answer 5

No law known of,   but any yellow that is too short to give a driver adequate time to react could be made an issue of in court for entrapment.

Answer 6

To my knowledge, there is no federal law.  There are guidelines/formulas that DOT's across North America, and even internationally should use.  Often times, failure to do this could bring penalties brought on by a state or federal agency.  But there is no law that I know of.

I think most DOT's go by the Institute of Transportation Engineers guidelines.  I think the average yellow lights are set to three to six seconds.

There is also the MUTCD (Manual on Uniform Traffic Control Devices) which is maintained by the Federal Highway Administration.

Answer 7

Agree with Jet Doc. The feds fund highways, but they are built by the states, to state specs, including the traffic lights.

The engineering idea is that the yellow gives you enough time to come to a full stop, if travelling at the full legal speed limit, without being caught in the intersection.

You could legitimately start shortening yellows as older cars, with worse stopping distances, are retired. But practically, you also need to acknowledge that people speed. And do other stupid things with cars.