Roadside posts

[Yorkie580]

What are the posts by the side of roads that have a florescent orange "roof" at the top of them? I keep seeing them but nobody I speak to seeems to know what they're for.

[Catso]

I don't know about yours, but around where I live they mark where gas mains (really big ones) cross roads. I've been told they are there so aerial surveys can track the course of the pipe. I was also told they check the pipes for leaks aerially, which sounds a little far-fetched to me!

[Grunty]

They can also be pipelines for oil, water etc. As Yorkie says, they are to guide helicopters when they are checking the line.

[heathfield]

The helicopters can carry 'sniffers' that test the air for gases from any leaks in the gas and oil pipelines. In the case of water, I guess they'd just look for a damp patch.

[teag1rl]

Not answer to riginal Q, but as to why surveys done from the air- Leaks can affect the vegetation-these changes can show up on aerial images.

[pezza.......]

From Wikipedia:

The Government Pipelines and Storage System (GPSS) is a United Kingdom pipeline system run by Oil and Pipelines Agency for the MOD. The network consists of some 2500 kilometers of pipeline and 46 other facilities. The network is interconnected with several private networks. The network was built before World War II and was used to supply fuel for Operation Pluto.

The locations of these pipelines are marked with identification posts with bright yellow roofs with a thick black line. Despite this in March 2000 at Furness vale near Whaley Bridge, High Peak, Derbyshire one of the lines was cut by workmen.

Private sectors usage is encouraged, but limited as the Oil and Pipelines Agency task is provide "maximum development of private sector usage of the GPSS, provided this does not impinge upon its primary purpose of supplying the required fuel for defence purposes and does not require capital investment from public funds."

Locations served by the GPSS include RAF Lakenheath, RAF Mildenhall and the Atomic Weapons Establishment.

see also http://www.linewatch.co.uk/network.htm

[pezza.......]

And here
http://www.linewatch.co.uk/aerial.htm

[Yorkie580]

Thank you everyone.