actually, most of the systems change it to all red so no one is moving
(at least in my area, it's certainly possible or even likely that there
isn't a nation wide standard), which also takes care of people trying to
turn.  and if the chase vehicle has to follow someone who keeps turning
the system may not have time.  emergency vehicles here do pretty much
whatever they want, i was shocked once in denver on a one way 4 lane
street when a large fire engine was coming at me head on!  they usually
cross intersections here by going around on the wrong side as well, it
works very well as long as people are actually paying attention for a
change.  i can see that rf would be bad for changing lights, since that
needs to be done well ahead of the vehicle and directionally, i was
suggesting an rf signal to allert drivers who for whatever reason didn't
hear it as quickly as they should.

Howard Winter wrote:
--------------
>
> Incidentally, in the USA if it's common for emergency
> vehicles to change the lights to green their way,
> howcome so many "World's worst police videos" show the
> suspect vehicle running a red light, just in front of
> the police car?
>
> Cheers,
>
> Howard Winter
> St.Albans, England.
>
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