Street lamp collapses on central reservation of Berkshire motorway

[whole diary]

[bobm]

From GetWokingham.  (Note the headline in the online article has a typo in it - it is the A329M)

All the steel columns on the A329M above Coppid Beech roundabout were tested after a street light collapsed and fell between the safety barriers
 
Wokingham Borough Council tested all the steel columns on this section and found five in a deteriorated state and at risk of collapsing after a street light recently collapsed and fell between the safety barriers on this section of A329M.
 
The dangerous elements of the five columns were removed immediately to protect driver^s safety.
 
Initial tests have been carried out and the remaining columns appear to be visually sound, but the council is awaiting data from an ultrasonic test, which is due in the next few days.
 
Councillor Keith Baker, executive member for strategic planning and highways, said: ^After a structural inspection on the 20 road lighting units on this section of the A329M above Coppid Beech roundabout, it was discovered five columns have become corroded and as a result have had dangerous elements removed as a precautionary measure.
 
^Lighting on the bridge is installed differently to the rest of the A329M, and as such, it is only this section that is affected.^
 
Call Wokingham Direct on (0118) 974 6000 to report any street lighting faults.

[Chris from Nailsea]

Purely out of idle curiosity on my part, and as a non-scientist (failed Chemistry ), what are those 'dangerous elements' apparently normally hidden in our street lamps?

[John R]

From GetWokingham.  (Note the headline in the online article has a typo in it - it is the A329M

Or even the A329(M) to be more precise.

[ellendune]

Purely out of idle curiosity on my part, and as a non-scientist (failed Chemistry ), what are those 'dangerous elements' apparently normally hidden in our street lamps?

It depends whether you are talking from an engineering or toxicological point of view.  I think the article was using the engineering view - in which case it was those structural elements that were abut to fail (or had failed) namely that part of the structure that had corroded to the extent that it was no longer strong enough. 

However, from a toxicological point of view the lamps in street lamps contain some metals that are not ideal.  Most now are high pressure sodium vapour lamps which is OK once it has reacted with air.  In the 80's though we used a lot of mercury vapour lamps which gave of a very white light. These definitely were toxic and safe disposal was an issue. All fluorescent lamps should be treated with caution though due to the possible chemicals in them.

A number of the metals have longer term toxic effects.  Bury a copper bare copper wire under your roses and you will discover how toxic copper is.  Zinc (think galvanised steel lamp posts) is also fairly toxic to aquatic life.

[stuving]

From GetWokingham.  (Note the headline in the online article has a typo in it - it is the A329M

Or even the A329(M) to be more precise.

Of course it should never have been called the A329(M), since the A329 exists in parallel. I have never heard how it came by this name - it was built from scratch, no part of it being an upgrade of anything.

I think the first example was the A1(M) Doncaster bypass, which was built along the old A1. The idea was to keep the route A1 continuous, so you could still say "follow the A1 until you get to Berwick". There is (or was) a principle that (unlike the USA) we do not have parallel roads with the same route name/number.

It is genuinely confusing, notably when you hear some traffic news on the radio, and end up unsure which was mentioned. Still, there is a plan locally to get it downgraded so it can be used for a proper ring road for Wokingham. It's not really part of the motorway network, and in any case the other half (towards Reading) is already the A3290.

[bobm]

It's not really part of the motorway network, and in any case the other half (towards Reading) is already the A3290.

It was originally intended to be a motorway link between the M4 and the M3 but the stretch between Reading and Bracknell was the only bit ever built.

The renaming of the northern end came about when the Park and Ride was opened at Winnersh Triangle and a bus lane built on the hard shoulder to get the buses ahead of the traffic into Reading.  In those days you could not have a bus lane on a motorway so they simply declassified it and named it the A3290.

[stuving]

It was originally intended to be a motorway link between the M4 and the M3 but the stretch between Reading and Bracknell was the only bit ever built.

That's all true, but hardly explains its misnaming. Wouldn't it have been the M329? And if this extension did happen to replace part of an existing A road, it would be the A322 - the A329 heads off westwards to Virginia Water.

[didcotdean]

If the motorway had been built as conceived it would have been the M31 - would have been a very useful route from the M4 to the M25 via the M3 - a bit of an outer circle and would have shortened the route from the West to South East by 10 miles.

[Electric train]

Thankfully the M31 was not built ripping its way through the Berkshire woodlands

Dig up motorways and turn them into railways 

[ellendune]

Thankfully the M31 was not built ripping its way through the Berkshire woodlands

Dig up motorways and turn them into railways 

Dual 3 lane motorway easily 6 tracks possibly 8!
Dual 2 lane motorway 4 tracks possibly 6!

[Pb_devon]

Just to drag you back to the original subject
Some years ago the streetlamp outside my house was replaced. The operatives told me that it was corroded at the base due to the attentions of the canine species.  Cannot imagine that would be the case in the middle of a motorway!!

[bobm]

I was wondering how the corrosion happened and the only thing I can think of is that, as it is a primary route, it gets salted and gritted more often than most roads.

[Electric train]

There is a thing called cathodic erosion caused by electrolysis, metal objects buried in the ground which could be high in alkaline or acid which are connected by a cable (the circuit protective conductor ........ in simple terms the electrical supply earth wire) you will get a current flow which over time will erode metal. 

I think this round about is far enough away from the railway third rail dc systems have a lot of stray dc current in the ground which will erode metal in its path.

Or .............. they could have just gone rusty ..................... que Magic round about music http://www.youtube.com/watch?v=k3LBq2ma9HQ 

[stuving]

You can go and look in Google Earth, if you want to. I think they look a bit discoloured, but see no sign of rust coming through the paint. However, this one (image dated 5/2012) has an obvious watertightness problem.

They do have this rather odd arrangement of two access hatches, so sealing could be a design problem. They appear to be bolted to the flat bridge surface, so may well have a closed base and need a drainage hole, which could be blocked. Then there's what looks like a damp patch on the concrete round the lamp - that's the same on all of them. So there's quite a few things that could make them liable to fail.

[didcotdean]

Thankfully the M31 was not built ripping its way through the Berkshire woodlands

Dig up motorways and turn them into railways 

If it were there now, the M25 and M4 wouldn't have been needed to be widened out as they are now. So losers as well as gainers, maybe. As it is the A322 struggles in its place.