Based on my investigation on the time of our yellow lights, it is designed for 25mph/ 40km/hr, not 50mph/80km/hr, that our maximum allowed speed is. In town, it is 50km/hr, suburb it is 70km/hr. No wonder there are many accidents at traffic junctions when cars are expected to stop suddenly beyond their capabilities.
I got this from this site: http://www.shortyellowlights.com/standards/
STOP Short Yellow Lights
Yellow Light Time StandardsLegislation mandating proper yellow light times is mostly non-existent. It is one of the goals of this project to establish national standards to protect motorists.
For the purposes of this project, we have put together a general guide to appropriate yellow light durations.
This guide is intended to help identify potentially dangerous short yellow light times. Whenever possible, suspicious timings will be confirmed by a trained, objective traffic engineer.
Recommended Yellow Light Times
Three seconds should be the absolute minimum time for any intersection.
25 MPH -- 3.0 Seconds
30 MPH -- 3.5 Seconds
35 MPH -- 4.0 Seconds
40 MPH -- 4.5 Seconds
45 MPH -- 5.0 Seconds
50 MPH -- 5.5 Seconds
55 MPH -- 6.0 Seconds
For your information, a technical explanation of the Institute of Transportation Engineers (ITE) formula for calculating yellow light times is included below (source):