M25 Traffic Lights - hillman1 {p}
Hi All,

I have noticed recently that a number of junctions in the south east corner of the M25 have just had traffic lights installed and wondered if anyone had an idea why they have been as I can't see there would be any real benefit. They are, according to the signs, only going to be used occasionally...

Also, if anyone knows what the building with the arched roof is that has recently been built just outside the M25 at, I think, Junc 14 is it'd be good to know and would help me to show a little intelligence in front of SWMBO who asked recently- I need all the help I can get to look intelligent :-(

M25 Traffic Lights - rtj70
It will be to control the flow of cars getting onto the M25 during busy periods.
M25 Traffic Lights - hillman1 {p}
That's what I thought, but does it really make that much difference. I can't say I have noticed a great increase in traffic over the past few years- it has always been pretty grim at rush hour- just wondered why now really....
M25 Traffic Lights - rustbucket
They are also at various junctions through Birmingham on the M6, when I have been on the M6 the ajoining traffic just enters in one mass block when their lights are green and they seem to think that they have right of way as they have just been given the green light.
M25 Traffic Lights - welshlad
traffic lights on the M25???..... what are they? red, amber and 'your kidding you aint going nowhere'
M25 Traffic Lights - pd
I think, but I'm not sure, they are to control queing traffic into the M11 and Holmesdale tunnels during busy times so a load of cars don't sit in there polluting themselves.

The sometimes close the Dartford barriers going into the tunnel for the same reason.
M25 Traffic Lights - Ben 10
Arched roof, junc. 14. That'll be Terminal 5 Heathrow.
M25 Traffic Lights - RobertyBob
Google: Ramp Metering
M25 Traffic Lights - ukbeefy
I saw similar lights on the QE2 Expressway in Toronto 20 years ago. The had most of their on ramps signalled that way. It was a very quick change - green for say 3 cars then red for 10 seconds then green for 3 cars then red for 10 seconds. it meant that when teh traffic got to the end of the ramp into the flow of traffic it was at least going say 25-30mph rather than queing down and trying to join at snails pace. something to do with some complicated flow algorithm - when speeds drop too low the whole thing bunches up and people stop.
M25 Traffic Lights - hillman1 {p}
Arched roof junc. 14. That'll be Terminal 5 Heathrow.

No, not T5, the one I am thinking of is on the outside of the motorway. It looks like it could be some sort of recycling plant, but not sure.
M25 Traffic Lights - Ben10
That building was used by the construction company while building T5 opposite. For storage, equipment, plant and concrete making.
M25 Traffic Lights - henry k
>>Arched roof junc. 14.
the one I am thinking of is on the outside of the motorway.
It looks like it could be some sort of recycling plant but not sure.

It is on the Colnbrook Bypass ( A4 ), just to the west of the M25,
It is Owned by Grundon
recycling plant grundon slough
for images and info
M25 Traffic Lights - hillman1 {p}
Thanks Henry, my world is a better place now I know... Much obliged.

M25 Traffic Lights - Ben 10
I think you are wrong Henry.
The link states it is about to be built. The building referred to is the one Ben 10 described.
M25 Traffic Lights - henry k
IIRC the Grundon building was completed a couple of years ago.
The main purpose of the link was for the illustration of the buildind shape.

"Grundon wins PPC approval for large EfW plant near Heathrow (06.01.04)"
".....should be completed by early 2005."

M25 Traffic Lights - hillman1 {p}
Thanks guys- the picture in the link Henry provided is the building I was referring to.
M25 Traffic Lights - henry k
Thanks guys- the picture in the link Henry provided is the building I was referring

And the smoke on Friday night was :news.bbc.co.uk/1/hi/england/berkshire/8053388.stm
M25 Traffic Lights - R75
They tried this at J3 on the M27 when joining to go east bound. It lasted for a year or so before they realised it did not work and took them out. Problem is at this junction that there is a lot of container trucks using this junction and it would let one of them through and no more traffic could get through until the next light change, which backed everything up onto the junction above!!!

A complete waste of money!!!
M25 Traffic Lights - LondonBus
Beg to differ.

The lights are part of a ramp metering scheme:


stuff here:

M25 Traffic Lights - loonykev
Ramp metering? I wonder how long it will be before some bright? spark in The Department of Transport comes up with the idea of motorists putting a £1 coin in a slot to gain access to the ramp? I hope they don't read this post! :)