Bridge strike Salisbury 7 October 2021

[Class800]

Does anyone know more about this? I was on the 18.39 service to London Waterloo from Cranbrook. We were held at a signal for 5 minutes approaching where the line from Warminster merges. The guard then announced that we would proceed 'at caution' because a road vehicle had collided with the bridge ahead. We crossed it very slowly - it was a road crossing - I believe the A36 on the edge of Salisbury. Despite the guard saying the bridge was 'damaged', we arrived in Salisbury only 10 minutes late, and the train the hour later was the same. Very little disruption. Does anyone know what happened to the bridge, i.e. did bricks fall out? If it was 'damaged', it surprises me the line was kept open.

 

[vikingdriver]

That A36 bridge is often getting bashed.

 

[Class800]

My greater interest in this situation is why the bridge strike was not particularly disruptive to trains (10 minute delay only due to proceeding at caution), while other bridge strikes have been known to cause lengthy line closures

 

[jopsuk]

My greater interest in this situation is why the bridge strike was not particularly disruptive to trains (10 minute delay only due to proceeding at caution), while other bridge strikes have been known to cause lengthy line closures

because presumably an engineer was able to get to the sitte quickly (factor 1) and assess the damage as being in need of repair but relatively minor. Bridges, vehicles and the speed at which the latter hits the former varies wildly so every case is different (there's 4-5 a day on average on network Rail bridges)

 

[Class800]

Makes sense - because it was near Salisbury so not in a remote area which helps accessibility

 

[High Dyke]

Makes sense - because it was near Salisbury so not in a remote area which helps accessibility

It depends on the grading of the bridge. Every bridge has a colour code to it (Red, Amber or Green). Depending on the designation at that location makes a difference to how trains are signalled.

 

[zwk500]

My greater interest in this situation is why the bridge strike was not particularly disruptive to trains (10 minute delay only due to proceeding at caution), while other bridge strikes have been known to cause lengthy line closures

If its the A36 plate girder bridge immediately outside the station, its a very substantial thing to move, so trains can run over it slowly after an initial examination by the driver (no deformation of track, no visible gaps in ballast etc), although it requires a detailed inspection to confirm linespeed.
The most disruptive strikes tend to be on arch bridges, because even a small crack can compromise the structure of the load bearing arch. That or hitting an intermediate pier that bears all the weight at that point.

 

[158747]

If its the A36 plate girder bridge immediately outside the station, its a very substantial thing to move, so trains can run over it slowly after an initial examination by the driver (no deformation of track, no visible gaps in ballast etc), although it requires a detailed inspection to confirm linespeed.
The most disruptive strikes tend to be on arch bridges, because even a small crack can compromise the structure of the load bearing arch. That or hitting an intermediate pier that bears all the weight at that point.

The bridge referred to is the stone arch bridge where the A36 passes under the line just before Wilton Junction.

 

[zwk500]

The bridge referred to is the stone arch bridge where the A36 passes under the line just before Wilton Junction.

Ah, thanks for the clarification

 

[Class800]

So, as it is an arch bridge, perhaps we were fortunate it wasn't more serious and more disruptive. Thanks for the inputs people have provided on this

 

[John Webb]

This is the bridge in question, I assume:
Railway bridge on Warminster Road

© Copyright Julian P Guffogg and licensed for reuse under this Creative Commons Licence.

 

[Llanigraham]

because presumably an engineer was able to get to the sitte quickly (factor 1) and assess the damage as being in need of repair but relatively minor. Bridges, vehicles and the speed at which the latter hits the former varies wildly so every case is different (there's 4-5 a day on average on network Rail bridges)

Not quite.
All bridges have been risk assessed and graded into, if I remember rightly, three levels, so at the lowest level trains can run at normal speed, then at reduced speed and then "all stop" at the highest level, but at the first two lowest levels the first train over will be required to cross under caution and inspect the line, just in case.
An inspector, often a MOM in the first instance, will also be on call and will check conditions, but that can obviously take a while.
And I think this is the bridge that an ex - member of this forum used to boast that he regularly drive over height trucks through because he knew the signage was incorrect.

 

[Deafdoggie]

There are very many reasons it can happen. There is, for example, a bridge at the south end of Stoke-on-Trent station that is signed, correctly, as being 10' 4" high. But a 10' 3" lorry or bus won't fit under it, as there is a dip in the road so the length of the vehicle means it isn't at road height at the lowest point.
Conversely, at the North end of the station the bridge there was for many years signed as 13' 4" High but a 13' 8" double decker bus fitted under with room to spare! There was a historical reason for this. More recently the bridge was renewed and road realigned and all is now correct. As an interesting aside, in a novel twist British Rail once ran a locomotive over the top of the bridge and onto the road!

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