Bridge parapet collapse between Laurencekirk & Stonehaven (15/01)

[HSTEd]

Two in a matter of.... (was it weeks?)

Are these common or is something odd happening?

 

[PG]

Two in a matter of.... (was it weeks?)

Are these common or is something odd happening?

Assume you're referring to Nine Elms?

One hopes they're not common...

 

[GRALISTAIR]

Climate change the driver possibly?

 

[PG]

Climate change the driver possibly?

More than likely.

Makes me wonder if (in the future) the GW electrification masts, which looked massively over engineered, will still be standing while the trackbed has disappeared...

 

[Durradan]

Now closed until end of service 31st January.

I'm hoping Scotrail decide to keep up ticket acceptance with the Citylink buses for next week then. Their replacement bus schedules time around (only shuttling between Stonehaven and Montrose) leaves some quite long waits for connections, though lockdown is probably affecting coach/driver availability in addition to passenger numbers.

 

[HSTEd]

I'm getting nightmares of a Hatfield esque fallout from these failures.

 

[PG]

I'm getting nightmares of a Hatfield esque fallout from these failures.

Local radio report this afternoon of some road closures early next week (Mon-Wed) to allow Network Rail to carry out other bridge inspections in the aftermath of this incident.

 

[InOban]

Network Rail are now tweeting that it will be closed until February with a clearer idea next week. It seems that they are still deciding what has to be done and how to do it.

 

[PG]

Network Rail are now tweeting that it will be closed until February with a clearer idea next week. It seems that they are still deciding what has to be done and how to do it.

Sounds like a thorough investigation is taking place as that tweet mentioned removing one track and ballast.

 

[D6130]

Now closed until at least 7th February according to Scotrail.

 

[800001]

Now closed until end of service 31st January.

Until 7th of February the line is confirmed as being closed by Network Rail.
The southbound line and ballast has been removed, north bound may also be removed.

 

[221129]

Latest update is closed until 22nd Feb.

 

[GRALISTAIR]

I assume they will use Geotextiles in the stabilisation works. Maybe a good time to invest in producers of that.

 

[bspahh]

There is an updated photo of the bridge repairs from Network Rail

at https://twitter.com/philatrail/status/1356285666418716678/photo/1

 

[swt_passenger]

It looks from that photo that whatever the initial cause, they’ve taken off the entire parapet along the full length now? ie the area to the left of the arch, which was still present in earlier photos.
But the repairs are still only to one side so far?

 

[InOban]

If, as has been suggested, the problem arose from pressure from the increased depth of ballast on the outside of the bend, then the whole length of parapet would be vulnerable and need replacement and reinforcement.

 

[swt_passenger]

If, as has been suggested, the problem arose from pressure from the increased depth of ballast on the outside of the bend, then the whole length of parapet would be vulnerable and need replacement and reinforcement.

That’s what I was thinking too, but I wasn’t so sure as to suggest it. Makes you worry where else is the same?

 

[PG]

If, as has been suggested, the problem arose from pressure from the increased depth of ballast on the outside of the bend, then the whole length of parapet would be vulnerable and need replacement and reinforcement.

If so would that necessitate a reduction in line speed in the future to mitigate against the effect of the pressure building up again?
Apologies if this is a completely daft idea, my understanding of civil engineering is somewhat lacking...

 

[edwin_m]

If so would that necessitate a reduction in line speed in the future to mitigate against the effect of the pressure building up again?
Apologies if this is a completely daft idea, my understanding of civil engineering is somewhat lacking...

The solution is probably to replace the whole parapet with something strong enough to withstand all the forces it has to bear. The parts of the parapet that didn't fall might only have been in marginally better condition or experiencing slightly less force for some reason, so would most likely have fallen sooner or later if not dealt with.

 

[HSTEd]

Well if the depth of ballast started causing issues, wouldn't the obvious solution be to install slab track over the bridge?

 

[GRALISTAIR]

Well if the depth of ballast started causing issues, wouldn't the obvious solution be to install slab track over the bridge?

Interesting thought - then retrofit to all higher risk locations of similar type presumably?

 

[Elecman]

Interesting thought - then retrofit to all higher risk locations of similar type presumably?

Well if the depth of ballast started causing issues, wouldn't the obvious solution be to install slab track over the bridge?

I think that would be classed as Enhancement and would need separate funding steam from DafT as it wouldn’t be a maintenance Renewal

 

[gingertom]

I think that would be classed as Enhancement and would need separate funding steam from DafT as it wouldn’t be a maintenance Renewal

you could argue it's preventative maintenance, for the avoidance of catastrophic failure.

 

[Elecman]

Maintenance is like for like any improvement is Enhancement irrespective

 

[Durradan]

There is an updated photo of the bridge repairs from Network Rail

at https://twitter.com/philatrail/status/1356285666418716678/photo/1

I'm guessing from the (pre-existing, I believe?) dirt road on the left hand side that access doesn't appear to have been as much of issue as it was with the derailment site over the summer.

 

[swt_passenger]

I think that’s still a temporary road that’s been built for the work. Theres another track just to its right, that forks south of the underbridge, and that’s the only one shown on satellite views.

I wonder if it’s easier to build a straight temporary access in what would be a ploughed field, than improve the existing track?

 

[PG]

As @swt_passenger has said, it's definitely a new access road they have built. This link shows the existing track which passes under the railway and the new access is adjacent to that.
https://gis.aberdeenshire.gov.uk/ma...=aberdeenshire&baseLayer=OS Colour&datalayers

 

[Nicholas Lewis]

If so would that necessitate a reduction in line speed in the future to mitigate against the effect of the pressure building up again?
Apologies if this is a completely daft idea, my understanding of civil engineering is somewhat lacking...

To increase linespeed the track has been canted up on the outside of the curve so you have more ballast pushing up against the wall potentially exerting sideways pressure on it through the passage of trains and creating an overturning moment causing failure. As RAIB seem disinterested in this and Nine Elms doubt we will every really know but maybe and FOI would liberate an answer.

 

[swt_passenger]

To increase linespeed the track has been canted up on the outside of the curve so you have more ballast pushing up against the wall potentially exerting sideways pressure on it through the passage of trains and creating an overturning moment causing failure. As RAIB seem disinterested in this and Nine Elms doubt we will every really know but maybe and FOI would liberate an answer.

There’s no obligation on RAIB to issue a quick public statement about whether or not they’re investigating a particular incident. You cannot really say yet if they are “disinterested”.

 

[221129]

To increase linespeed the track has been canted up on the outside of the curve so you have more ballast pushing up against the wall potentially exerting sideways pressure on it through the passage of trains and creating an overturning moment causing failure. As RAIB seem disinterested in this and Nine Elms doubt we will every really know but maybe and FOI would liberate an answer.

Given that there was no accident or near miss there isn't really anything for them to investigate.