Red Light Cameras! Love them Or Hate Them...?

[agentsteel53]

most on-demand lights take several seconds to change.  When the car pulls up to the red light, the green on the intersecting road does not immediately go to yellow.  There is a known interval of time for this light to stay green.  That interval, when activated, should be put on the counter.  If there is no side street traffic, then the counter can be off. 

Usually I can see side-street traffic approaching and figure the light is about to change, but the counter would still help.

why does the MUTCD forbid them?  They seem like a good practical idea.

[vdeane]

Does being banned in the MUTCD even mean anything?  New York switches to it (with a supplement) recently, so box street names are no longer allowed here, but aside from four signs on I-81, no effort has been made to remove the boxes.

[andytom]

ITE has a widely-accepted formula based on speed and other factors, but it is only recommendation and its use is not binding on a wide scale (although some jurisdictions may have adopted it as a standard).

I know that, in OR law, use of the ITE standard must be used at red light camera intersections.  I don't know about that WRT non-camera intersections.

--Andy

[roadfro]

most on-demand lights take several seconds to change.  When the car pulls up to the red light, the green on the intersecting road does not immediately go to yellow.  There is a known interval of time for this light to stay green.  That interval, when activated, should be put on the counter.  If there is no side street traffic, then the counter can be off. 

Usually I can see side-street traffic approaching and figure the light is about to change, but the counter would still help.

why does the MUTCD forbid them?  They seem like a good practical idea.

In the situation you describe, with the car pulling up on the side street, the time before the light changes is not necessarily known.  If the signal has actuation and passage gap detection on the main street, the remaining green time will vary depending on the amount of traffic flowing on the major street.  A new car approaching on the main street will reset the passage gap timer resets and the time to yellow increases.  This would render a countdown timer for the green ineffective, because the number can increase--most modern signals are programmed with a passage gap setting.  This is one of the main reasons why the concept is disallowed by MUTCD.  The idea is practical only for pretimed signals.

I know that, in OR law, use of the ITE standard must be used at red light camera intersections.  I don't know about that WRT non-camera intersections.

I'm glad Oregon has this codified in law.  It's probably not the case in many jurisdictions.