Bruce wrote on 28 July 2009 15:34:18 ...
On Tue, 28 Jul 2009 14:27:58 +0100, Mike Bristow
wrote:
In article ,
Derek Geldard wrote:
It's probably done on purpose on grounds of cost: lights with a
fixed (or timed) pattern will be cheaper to buy and maintain than
lights with sensors etc.

That, as I understand that would be illegal.

I find that difficult to believe. I don't think the lights at the
junction of Bush Road and Leytonstone High Road have sensors, for
example. they certainly don't have the obvious ones that sit on
top of the lights (although they might have a loop in the road
itself, I suppose).

As Bruce says, most permanent lights have detector circuits embedded in
the road surface. At that junction, Google Street View seems to show an
anti-skid surface, which would have covered the tar lines indicating
where the detectors are.

No traffic lights on a public road, whether temporary or permanent,
can be installed without sensors.

What law or regulation specifies that? I'm not aware of one. Certainly
it's normal to have sensors, but I thought that fixed-time signals were
still legal. A Highways Agency press release from 2006 talks about a
fixed time traffic light installation at York being upgraded, and
Worcestershire County Council's site says that fixed time temporary
lights need their written approval, so in both cases it seems that fixed
time signals are not illegal.
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)