rail wrote:
In message
"John Rowland"
wrote:

rail wrote:
[snip]
Are you aware why they switch the sirens off once they have crossed
the junction?

It could be that the emergency has been cancelled, but if you have an
explanation for why this started happening after the Menezes
incident, I'd like to hear it.



It didn't start after the Menezes incident, it is to reduce the
amount of noise polution, which has the advantage of making the siren
more noticeable when it is used. If you here a siren going
continuously for a while you tend to blank it out. Fire engines and
ambulances do the same thing.

You're talking about when they put the siren off and leave the lights
flashing. I said
"I have frequently seen police vehicles pull up at a red light, wait for ten
seconds, get bored, put on the flashing lights, drive through the junction
and then put the lights off again"
About the Greenwich incident I should have said "Once a police car even
pulled up behind me in Greenwich town centre and put the lights and sirens
on (at 3am!) causing me to drive through the red light out of their way, and
then they drove through the lights and put the lights and sirens off."