Bascule bridge Network Rail sign???

[truckman060473]

Just wondering about this odd sign that has been put up recently on the wall of the bridge at Carmarthen where the river walk footpath runs under. It mentions a blockage of the waterway and to phone a number. Are they referring to a flood? Because suffice to say, should the water be high enough to get near the tracks - (virtually impossible) how the heck is a member of the public going to be down on that river walk and read that sign when the banks of this tidal river are flooded!!!!!

 

[ralphchadkirk]

As seen at Feltham last year(?), a partial blockage of the culvert caused the water dynamics to change, and effectively undermined part of the bridge causing a section of it to collapse.

Here's the RAIB report:
http://www.raib.gov.uk/latest_news/news_archive/news_archive_2010/100923_pn_feltham.cfm

I've quoted the relevant part of the summary:

On the evening of Saturday 14 November 2009, the foundations of a 170 year old brick arch railway bridge failed without warning, causing part of the bridge to subside. The driver of a train crossing the bridge reported a track defect, which track staff subsequently identified as a serious structural defect. There were no injuries caused. The bridge has since been demolished and rebuilt.

The RAIB investigation identified that the immediate cause of the incident was that the east abutment of the bridge was undermined by scour. Causal factors were:

an obstruction in the watercourse, which channelled the flow towards the east abutment, increasing its velocity and making it more likely that scour would occur;

 

[HugePilchard]

I think that, rather than a flood they're referring to things that might cause problems, such as a tree trunk wedged across the main span or something like that.

 

[GB]

Not about floods reaching the track but about the water flow getting restricted or channeled towards the bridge supports causing structural failure.

...as seen here...

http://www.raib.gov.uk/cms_resources.cfm?file=/100923_R172010_Feltham.pdf

 

[swt_passenger]

The thing about Feltham was that a few locals had noticed the problem, but it wasn't obvious how to report it - so in principle signs are a good idea.

I've also noticed the usual 'bridge bash' signs on some bridges over the canals where it would be impossible for the normal canal traffic to hit the bridge, but I guess like a lot of things these days they'll just apply precautionary signs to everything where it is remotely possible there could be a problem, it will probably be cheaper to stick up a few too many signs than to get someone to make a decision.

A sensible decision on where to put them would need committees, reviews, consultations etc after all wouldn't it... :roll:

 

[truckman060473]

What is the 245m 33ch ? I'm probably wrong, but if it means metres and chains, the bridge is not 245m long and the track is straight across it (if 33ch means the radius of a curve)

 

[ralphchadkirk]

What is the 245m 33ch ? I'm probably wrong, but if it means metres and chains, the bridge is not 245m long and the track is straight across it (if 33ch means the radius of a curve)

It's the mileage of the brige. The sign gives the Engineers Line Reference, the and the number of miles and chains from the zero point to the structure.

 

[Tomnick]

245 miles and 33 chains, most likely from London Paddington.

 

[142094]

IIRC DaveNewcastle posted a similar story about a bridge where a tree trunk had caused a simlilar obstruction of the water course which led to the undermining of the bridge, causing it is degrade. Normally there is a sign attached to bridges in case of a strike involving vehicles but this is the first I've seen due to natural causes.