Does Network Rail have an over-engineering problem?

[J s]

One thing to bear in mind is precisely which variables you are optimising for. Once upon a time you optimised for material usage as that was where the cost of building lay. Labour was cheap. Nowadays there is much more focus on optimising for speed and minimising labour as they are much more dominant components of the overall cost of construction. If your design is chunkier but can be lifted into place in one go in one night then maybe that’s not such an irrational response?

The railway also has exceptionally low tolerance for risk and a desire to future proof which only promotes more robust conservative designs.

 

[GRALISTAIR]

This doesn't make sense - you surely have to balance the cost of building 1000s of masts strong enough to withstand the impact of a derailed train, with the cost of replacing one slimmer mast, in the very rare event of a train derailing.

Additionally, it is surely much preferable that an electrification mast distorts on impact, than the train body.

That’s what I was thinking and I am glad you said it first.

 

[The exile]

S

do they get the extreme swings we get though?

Over the course of time, yes, though I suspect the tendency to experience all four seasons before lunchtime drops as the climate becomes more continental. In terms of vertical structures, I suspect the toughest feature of our climate is wind - but even there, the difference is probably how often it is very windy rather than the severity of the occasional “extremely windy”

 

[DazT]

I understand that the design on the WCML that tried to address the apparent over engineering was not a success. The signal heads could be lowered to the ground to avoid working at height. I don't think they were ever installed anywhere else but happy to be corrected.

Any at height signals need a walkway that is strong enough to carry the weight of the equipment, the staff up there and what ever heavy tools you need so I think there's much choice!

Raised not lowered, crown post signals, but still require working at height, just that the signal head can be wound up out of position so it's easier to work on.

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On my patch, we have a load on the Tring workstation area, some around Hanslope and north of Polesworth (IIRC all the way to Armitage [former site of])

 

[osmarks]

Perhaps the question could be: are external physical systems necessary when we could put it all in the cab and/or automate it? Removes the maintenance liability and initial infrastructure cost; existing systems elsewhere in the world (thinking very high speed rail) probably already do this. (Note I am not advocating for one or the other.)

The standard for in-cab signalling here is ETCS, which is being installed on the south ECML, but it's proving absurdly expensive for unclear reasons.

 

[Nicholas Lewis]

Additionally, it is surely much preferable that an electrification mast distorts on impact, than the train body.

At Hatfield the OLE mast in the main path of the derailed train gave way and did significant damage to one of the coaches. So when you look at the scale of GWR OLE masts and the signal gantry structure above they will present a very hard structure should a derailed vehicle hit them unless the mast bolts are designed to shear if subjected to high lateral force.

Clearly the engineers also have to have structures that arent vulnerable to failure as that would be equally catastrophic so a balance has to be struck.

 

[RUK]

This doesn't make sense - you surely have to balance the cost of building 1000s of masts strong enough to withstand the impact of a derailed train, with the cost of replacing one slimmer mast, in the very rare event of a train derailing.

Additionally, it is surely much preferable that an electrification mast distorts on impact, than the train body.

I was thinking if the wires could come down and electrocute people.

 

[59CosG95]

In the case of the ECML masts, the slimmest of them (152x152 Universal Columns) have been more prone to Lateral Torsional Buckling than its thicker cousins (e.g. 203UC, 254UC, 308x305UC etc) so aren't available in newer design ranges.

 

[Sir Felix Pole]

I've noticed the same with regard to the electrification of the Welsh valleys: the masts supporting the wires are overbearing and very unattractive. Perhaps unsightly structures are cheaper to erect than elegant ones.

And don't get me started on the ugly footbridges that are appearing across the network...

I went through Abergavenny recently, and was astonished by the absolutely enormous footbridge / lifts recently erected there. It might be appropriate for somewhere like Cardiff Central but is totally over-engineered for what was an attractive country station - it is completely overpowering and dominates the scene. (I know there was an unfortunate incident with the old bridge where someone got electrocuted due to a loose cable slung along it, but even so).