Short yellows at Chicago's red light cameras

[roadman]

Those "yellow lights shorter than 3 seconds" turn out to be . . . .

2.94 seconds.

That might be a scandal on big suburban arterials, but not so much in the city, where the speed limit is 30 mph and no street is wider than 76 feet.

Sorry: The minimum for a yellow light is 3 seconds, not "close to" 3 seconds.  And what does width have to do with it?  Traffic light timings are based on posted speed and/or 85th percentile speeds.  Not width of roadway.

As I understand the ITE formula, yellow intervals are based on approach speeds and width of the intersection that the vehicle has to clear.

[roadfro]

Those "yellow lights shorter than 3 seconds" turn out to be . . . .

2.94 seconds.

That might be a scandal on big suburban arterials, but not so much in the city, where the speed limit is 30 mph and no street is wider than 76 feet.

Sorry: The minimum for a yellow light is 3 seconds, not "close to" 3 seconds.  And what does width have to do with it?  Traffic light timings are based on posted speed and/or 85th percentile speeds.  Not width of roadway.

As I understand the ITE formula, yellow intervals are based on approach speeds and width of the intersection that the vehicle has to clear.

The ITE formula for the yellow change interval is based on the approach speed (typically 85th percentile speed or posted speed limit), deceleration rate, and grade of the approach. No width of roadway term is included.

It is the ITE formula for the red clearance interval that includes width or intersection, as well as length of vehicle and approach speed.