East-West Rail (EWR): Consultation updates [not speculation]

[richieb1971]

I thought the Bletchley flyover was mostly the reason the EWR project was financially viable in the first place. To replace most of it seems to have eradicated any advantage it gave in the first place.
I guess it was in poor condition for trains to go over it, rather than trains go under it. Or did the EWR team just find out its a liability on both fronts?

 

[edwin_m]

I thought the Bletchley flyover was mostly the reason the EWR project was financially viable in the first place. To replace most of it seems to have eradicated any advantage it gave in the first place.
I guess it was in poor condition for trains to go over it, rather than trains go under it. Or did the EWR team just find out its a liability on both fronts?

Network Rail would be inspecting it periodically, not just the spans that went over roads or other lines, because of the safety risk if it had collapsed. But being safe to support itself doesn't mean it's safe to support a train, or in the worst case a train on each track. I don't think we know when it was established that parts of it needed replacement, or how many such replacements were budgeted for in earlier stages. They might even have assumed the whole lot would need doing, so any parts that remain represent a saving!

 

[swt_passenger]

Network Rail would be inspecting it periodically, not just the spans that went over roads or other lines, because of the safety risk if it had collapsed. But being safe to support itself doesn't mean it's safe to support a train, or in the worst case a train on each track. I don't think we know when it was established that parts of it needed replacement, or how many such replacements were budgeted for in earlier stages. They might even have assumed the whole lot would need doing, so any parts that remain represent a saving!

The Planning application to replace sections was comparatively recent, (Dec 2019) and it certainly read as though they had fully expected to use the existing viaduct following a certain amount of maintenance and waterproofing work.

 

[mwmbwls]

Yes - that was the original plan but the inherent nature of reinforced concrete with the interplay of reinforcing bars, cement and aggregate is always complex. Every atom of steel has a the ambition of growing up to be rust and having done they pass it on to their chums. Thinking about maintainabilty as well as constructability now plays a larger part in life cycle calculations.

 

[Bald Rick]

I thought the Bletchley flyover was mostly the reason the EWR project was financially viable in the first place.

In a billion pound project, the difference between a significant refurbishment and partial reconstruction of one flyover is basically ‘noise’ in the cost.

 

[The Ham]

Hmm, let's hope the electrification happens quickly then, since taking a diesel train instead of an electric car wouldn't decarbonise much

Taken as an average 10,000 miles on the UK railways the per passenger emissions are 0.59 tonnes.

This compares with 0.60 tonnes for EV's.

However even that comparison isn't that great as there's a load of miles which people will drive that they can't go by rail, if those are mostly done by walking/cycling then that drops the emissions further for rail.

You also have to bear in mind that the maintenance of the railways (9,800 miles worth) produce less emissions than the maintenance of the strategic road network (4,800 miles).

 

[hwl]

Yes - that was the original plan but the inherent nature of reinforced concrete with the interplay of reinforcing bars, cement and aggregate is always complex. Every atom of steel has a the ambition of growing up to be rust and having done they pass it on to their chums. Thinking about maintainabilty as well as constructability now plays a larger part in life cycle calculations.

The issue is with the bearings where the support beams weren't perpendicular to the viaduct alignment. Hence replacing those sections as well as the adjacent ones.

Highways England have plenty of similar issues...

 

[Roast Veg]

Every atom of steel has the ambition of growing up to be rust and having done so they pass it on to their chums.

An adorable, if concerning, issue.

 

[camflyer]

Yes - that was the original plan but the inherent nature of reinforced concrete with the interplay of reinforcing bars, cement and aggregate is always complex. Every atom of steel has a the ambition of growing up to be rust and having done they pass it on to their chums. Thinking about maintainabilty as well as constructability now plays a larger part in life cycle calculations.

Of course, to be pedantic, there is no such thing as an "atom" of steel as it is an alloy.

 

[Tobbes]

Of course, to be pedantic, there is no such thing as an "atom" of steel as it is an alloy.

OK, so strictly the Fe atoms become hydrated ferric oxide, or approximately Fe2O3

 

[jfowkes]

Forgive me if this has been asked before, but was the viaduct expected to be this bad? It's not a terribly old structure is it? Was the deterioration worse than expected or was it at the end of its design life anyway?

 

[hwl]

Forgive me if this has been asked before, but was the viaduct expected to be this bad? It's not a terribly old structure is it? Was the deterioration worse than expected or was it at the end of its design life anyway?

Worse than expected in one particular area (the bearings) and the bridge decks would have had to be jacked up in pairs (twice per deck) to address hence very disruptive to the WCML undeneath.
Generally in quite good condition.

 

[richieb1971]

When can the first track on the mothballed section expect to be laid?

 

[The Planner]

When can the first track on the mothballed section expect to be laid?

Still probably a year away, if not more.

 

[mwmbwls]

Of course, to be pedantic, there is no such thing as an "atom" of steel as it is an alloy.

Thank you - I stand corrected.

 

[hwl]

Still probably a year away, if not more.

Plenty of civils and structures work to do (and no sign of it starting) before it is worth laying any track, I'd go for first track in 2022

 

[Bald Rick]

Plenty of civils and structures work to do (and no sign of it starting) before it is worth laying any track, I'd go for first track in 2022

Agreed. Track is one of the last things to do. A year before opening probably.

 

[DelW]

Forgive me if this has been asked before, but was the viaduct expected to be this bad? It's not a terribly old structure is it? Was the deterioration worse than expected or was it at the end of its design life anyway?

Around 60 years old, which is a fairly typical design life for an RC structure. Plenty of motorway bridges of that era have needed major repairs or replacement.
It's often the ancillaries which fail (e.g. bearings, expansion joints) which then cause adverse effects on the main structural elements.

 

[BrianW]

Re Bletchley viaduct- It could have been worse. It could have been a 'listed' structure needing to be kept for posterity- after all it was surely of historical interest having been closed so soon after opening- maybe a record? I don't know dates or comparotors- maybe a Forumite (like Bletchleyite maybe?) will advise? Has the Concrete Society not complained?

 

[Bald Rick]

Has the Concrete Society not complained?

They are rather set in their ways.

 

[BrianW]

They are rather set in their ways.

Apparently rather as an alloy has not atoms (see above) concrete cures rather than sets

 

[The Ham]

Apparently rather as an alloy has not atoms (see above) concrete cures rather than sets

Which is why I resisted referencing rods for their own backs, as as it's bars and generally someone else makes them.

 

[mwmbwls]

Around 60 years old, which is a fairly typical design life for an RC structure. Plenty of motorway bridges of that era have needed major repairs or replacement.
It's often the ancillaries which fail (e.g. bearings, expansion joints) which then cause adverse effects on the main structural elements.

The viaduct was built between 1958 and 1960 as part of the WCML electrification programme. The overhead at that time was fixed directly to the viaduct.

 

[STEVIEBOY1]

Have plans been drawn up for a new Bletchley Viaduct?

 

[DarloRich]

Have plans been drawn up for a new Bletchley Viaduct?

I don't know what you mean? It isn't a new viaduct as such. As work has started I would hope there was a plan in place!

 

[DarloRich]

I thought the Bletchley flyover was mostly the reason the EWR project was financially viable in the first place. To replace most of it seems to have eradicated any advantage it gave in the first place.
I guess it was in poor condition for trains to go over it, rather than trains go under it. Or did the EWR team just find out its a liability on both fronts?

That isn't accurate. The existence of the flyover made it easier to justify the cost but the existence of the flyover was not the key driver behind the business case. To think that it is was is worrying and suggests the benefits of the project have been missed despite the publicity.

BTW - The flyover was not going to fall on anyone!

Worse than expected in one particular area (the bearings) and the bridge decks would have had to be jacked up in pairs (twice per deck) to address hence very disruptive to the WCML undeneath.
Generally in quite good condition.

Indeed - it is less disruptive to train services to replace the sections. It is more disruptive to road users in Blethcley mind!

 

[DelW]

Have plans been drawn up for a new Bletchley Viaduct?

It's to be hoped they have, since the current demolition is in preparation for it!

It will be essentially a concrete box over the WCML tracks, with the existing outer spans of the old viaduct connected to it. I think there were some sketches earlier in the thread.

 

[edwin_m]

Re Bletchley viaduct- It could have been worse. It could have been a 'listed' structure needing to be kept for posterity- after all it was surely of historical interest having been closed so soon after opening- maybe a record? I don't know dates or comparotors- maybe a Forumite (like Bletchleyite maybe?) will advise? Has the Concrete Society not complained?

Although the original purpose it was built for never materialized, the flyover itself remained in occasional use, possibly right up until the track was removed for the current works, and it's probably still officially "open" now.

Have plans been drawn up for a new Bletchley Viaduct?

I would imagine replacement spans have been designed and are probably in manufacture.

Which is why I resisted referencing rods for their own backs, as as it's bars and generally someone else makes them.

Reading that just reinforced my view that people are getting too pre-stressed about this. In the aggregate it doesn't make much difference.

 

[DarloRich]

Around 60 years old, which is a fairly typical design life for an RC structure. Plenty of motorway bridges of that era have needed major repairs or replacement.
It's often the ancillaries which fail (e.g. bearings, expansion joints) which then cause adverse effects on the main structural elements.

i understand it is the bearings not the structure that is the issue here.

 

[The Ham]

Reading that just reinforced my view that people are getting too pre-stressed about this. In the aggregate it doesn't make much difference.

Very good.