I think it is tied to the speed limit.
The higher the speed limit the longer the duration of the yellow.
The higher the speed limit the longer the duration of the yellow.
The length of yellow lights varies by city and state? And if the timing of a yellow light isn't set correctly, the likelihood of an accident increases as well. The US Federal Highway recommends standards, but no state uses them [they're actually designed with safety, not revenue in mind]
NY Traffic Signal manuals
https://www.dot.ny.gov/divisions/op...stems/repository/B-2011Supplement-adopted.pdf
https://www.dot.ny.gov/divisions/engineering/design/dqab/hdm/hdm-repository/chapt_11.pdf
The federal standards for traffic control devices can be found in the Manual on Uniform Traffic Control Devices (MUTCD), which is published by the Federal Highway Administration (FHWA).
http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP03-95_FR.pdf
https://www.thedrive.com/news/30530...-may-not-be-long-enough-after-all-experts-say
Here's a group pushing for the more conservative and safety driven amber lengths [formula provided]
http://www.shortyellowlights.com/standards/
https://blog.photoenforced.com/2011/02/what-is-proper-length-for-yellow-light.html?m=1
This manual might help if you want to fight a red light ticket with a very technical defense.
http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP03-95_FR.pdf
Red/amber light study
http://www.jctconsultancy.co.uk/Sym...ength%20of%20amber%20times%20at%20signals.pdf