Wall collapse at Wigan North Western

[Moxy]

This has been reported widely on social media locally

 

https://twitter.com/hashtag/WiganNorthWestern?src=hash

 

Part of the viaduct carrying Wigan North Western has collapsed onto Queen Street, which runs parallel to it.

 

There are thankfully no injuries reported, but the station was closed briefly whilst engineers examined the damage.  Network Rail report it has reopened, but with speed restrictions in place.

 

From the station level, this is the side closest to Platform 6.

 

Hope this is repaired soon.

[gismorail]

It amazes me that incidents like this are not more regular throughout the whole of the railway network as so much of the infrustructure is totally worn out and in need of urgent attention which will only be attended to once something falls down ...

[APOLLO]

My son was on the platform waiting for the Liverpool train when it happened - though he saw nothing. Station was evacuated and luckily he was able to walk across the road to Wallgate and get to Liverpool by changing at Kirkby. Services back to normal(ish) now, but roads still closed and platform 6 at NW closed. This is used mainly by Liverpool EMU stoppers that reverse here.

 

Info here   http://www.bbc.co.uk/news/uk-england-manchester-38166611

 

 

The bit that collapsed was the old passenger subway entrance, not used for many years, perhaps back to the 50's. I never remember it in use, always bricked up at this end and steps removed. The other arches are commercial premises, one being the Great central railway themed pub (nice pint !!).just out of the photo above to the left.

 

 

There are no railway lines directly above these arches, being the old platforms 9&10 removed when the station was rebuilt and the line was electrified in 1973

 

This is an EMU in platform 6 looking north. You can see where the old platforms & lines where behind. The passenger subway is approx at the rear of the EMU. Still in use to the other platforms / exit to the right. The walled up bit which collapsed is to the left, adjacent to the wall.

 

 

Similar view over 100 years ago on 2 Aug 1873 when the northbound scotch express derailed on points, with 13 casualties.

 

 

Brit15

[andyman7]

Victorian era infrastructure finally failing after 150 years.  Wonder how long our infrastructure will last.  Oh, it doesn't.  Too much emphasis on reduced structural margins and increased profit margins.

 

JF

Victorian infrastructure was in most cases ridiculously over-engineered because they lacked the knowledge to accurately calculate structural loads. In many cases that has meant that Victorian constructions have been able to cope with loads many times in excess of the original design parameters, but the flipside were incidents like the original Charing X roof collapse or the Tay Bridge disaster. 

 

Nowadays, structural margins are calculated with much greater certainty. That represents a mature industry. Ironically the modern era of safety cases means that the margin is actually higher than 20 or 30 years ago (which has an impact on costs) but I would not accuse the modern railway of being under-engineered.

[Zomboid]

Engineering is about doing the minimum to meet the specified requirements.

In the instance of new bridges, that includes a design life of something like 125 years.

Of course, if it is to last in service that long, a sufficient allowance has to be made for future changes of use, but that's down to the specification, not the engineering.

[TheSignalEngineer]

Victorian era infrastructure finally failing after 150 years. Wonder how long our infrastructure will last. Oh, it doesn't. Too much emphasis on reduced structural margins and increased profit margins.

 

JF

During the Jewellery Line project a lot of infrastructure which had seen low or no use for a number of years had to be refurbished. Victorian blue brick structures were in relatively good condition, generally needing cleaning, pointing and track bed waterproofing installing. Many steel structures were badly wasted and had to have extensive work. The biggest surprise was at a bridge carrying a major road where the 100 year old brick arch which was done up during roadworks about 25 years before required little work but the new concrete span adjacent was falling apart.

[TheSignalEngineer]

Duplicate post deleted

[APOLLO]

Engineering is about doing the minimum to meet the specified requirements.

 

Not in the gas industry back in the early 70's. We engineered & constructed high pressure pipelines and associated plant to the very highest world wide standards available at that time, NEVER down to a cost.

 

God knows what goes on today though !!.

 

Brit15

[Zomboid]

That would be because the specification required that. It would have been engineered to meet that standard, but you have to stop somewhere.

 

Where did I say anything about cost? Engineering is about doing the job but not doing unnecessary fluff. If you 'engineer' something down to a cost you have to start deciding which of the requirements you don't want to meet. You then end up with something that doesn't do everything it's supposed to do.

[ejstubbs]

As the old saying goes: good, quick, cheap - pick two.

 

(This is also one of the fundamentals of project management: the classic triangle of cost vs schedule vs quality.  PM methodologies which add to these three are over-complicating things unnecessarily, either with irrelevancies, or with things which are really embedded within the fundamental threesome.)

[Dunsignalling]

The difference between old and new civil engineering is that, nowadays, stresses, loads and material properties are much more "known quantities" so structures can be designed to carry the expected loads for the expected period of need, in both cases with a calculated safety margin.

 

The Victorians had much less detailed understanding of such things so worked to the old adage of "if in doubt, make it stout, out of stuff you know about" and worked out new developments as they went along. Incidents like the Tay Bridge collapse resulted from certain engineers pushing forward too quickly or skimping on materials (or both). More generally, "permanent structures" were not considered to have a finite lifespan.

 

Hence, large numbers of their railway structures remain in daily use more than a century-and-a-half later, carrying trains of weights and speeds they cannot have contemplated, whereas anything designed today that is intended to last 100 years will pretty definitely need replacing a decade-or-so afterwards even if increasing demands haven't rendered it inadequate before that.

 

John

[stewartingram]

Reminds me of the Cambridge misGuided Busway.

Over budget, over time, designed for a 15 year lifespan!

And now having to have a major upgrade after being open 5 years.

 

Stewart

[Reorte]

Thank goodness for us that the Victorians did over-engineer, so when things do eventually fall apart they do so well spread over time. The chaos that'll be caused when the designed-to-a-lifetime motorway bridges all start needing replacing at around the same time doesn't bear thinking about. The odd one or two individual ones that have needed replacing already have been trouble enough.

 

I can't help thinking though that if we don't want old but still in use structures to fall down then perhaps having forests sprouting out of the brickwork is probably not the best idea. They're probably well-enough established by now though that the damage has been done and can't be removed without causing more. Seems rather short-sighted.

[John_Miles]

The salt corrosion problem has been present in the UK for over 20 years. Reinforced concrete structures which were supposed to last for at least 100 years have had to have remedial work after around 20 years and some have even been demolished. A particular problem has been water ingress at joints which were supposed to be water proof. Masonry structures will stand huge amounts of neglect and even support extensive plant life, as can been seen on today's railway.

[Jamie]

Sad to see such disdain for both engineering and materials science.  

Three things we're great at in this country: engineering, science, and withering disdain. 

 

Yes we're lucky to be able to continue to use much infrastructure left to us from our forebears.  But let's not kid ourselves - everything has a capacity limit and lifespan.  Even Victorian brickwork (and I love it too) will not give you the "infinite cycles" demanded - due to weathering, defects and probable future usage needs.  How do you predict the needs of society 100 years ahead?  The Victorians didn't - witness all those redundant railway viaducts.

 

Another truth is clear, you cannot design against every eventuality.  There will be both normal operation cases and extreme cases.  It could be for various reasons - climate change, usage pattern changes, whatever - that what is now considered an overestimate becomes the norm.  "Reasonably foreseeable" has to be quantified, or we're just blindly chucking materials and cash at a problem.

 

We're still learning about all materials - one of my lecturers was researching the mechanics of masonry with a view to understand its dynamic behaviour - and even then, we're always building on probably the biggest variable of them all: the ground beneath our feet.

 

 

But we've maybe gone off-topic relative to the (fairly) minor structural failure in the subject line.

[Dunsignalling]

I certainly wouldn't shower any disdain upon materials scientists - they are indisputably more knowledgeable than their Victorian forebears. 

 

However, being able to calculate with greater certainty what will be "good enough" for the anticipated use and lifespan of a proposed structure carries its own burden; primarily the increased influence of "bean counters" in the process who will always want to shave a bit more off the cost.  

 

As for those redundant Victorian viaducts, they did what they were built to do for as long as it needed doing; probably exactly what their builders intended. Nowadays, many have found new uses saving walkers and cyclists from tiresome gradients  and they won't wear them out in the next 150 years.

 

Others continue to grace our landscapes whilst doing no more than holding hills at the correct spacing.   

 

John

[APOLLO]

Just north of Wigan North Western on the west coast mainline is Frog Lane bridge. This bridge is 100% original, built by the North Union railway around 1838. I park near here when visiting town and I always marvel when walking underneath at its stone construction with a skew brick inner arch, now carrying modern Pendolinos and long double headed container trains at speed, unimaginable loads when it was built.

 

 

Hopefully this will last another 178 years !!

 

Brit15

[Zomboid]

However, being able to calculate with greater certainty what will be "good enough" for the anticipated use and lifespan of a proposed structure carries its own burden; primarily the increased influence of "bean counters" in the process who will always want to shave a bit more off the cost.

The problem is that said "bean counters" don't understand that a well engineered solution generally won't have anything to shave off without compromising its ability to work as intended.

 

The other side of that is that if we used Victorian margins these days we would be able to do about 15% of the laughably inadequate infrastructure projects that we do in this country.

[APOLLO]

This is the M6 motorway viaduct over the railway, river and canal at Gathurst near Wigan.

 

 

Those concrete pillars have recently been extensively repaired due to concrete spalling and rusting steel reinforcing. God knows whats going on deep inside them. The steelwork deck may be well engineered but the supports won't last a lot longer - certainly not 178 years.

 

Brit15

[jamie92208]

The Victorians didn't always get it right. The early bridges were mainly built by engineers who had learned the job on canals and were a many say vastly over engineered. The stone ones have lasted wonderfully well. There were problems with cast iron bridges and one or two nasty collapses when the Stephenson's used cat iron under tension. However by the 1860's scientific engineering design was coming in and metal bridges became more common. As far as I know they started to be designed to carry a certain weight per foot. They used the weight of the current locos as a guide with a safety margin. This was OK until the early part of the 20th century but by then loco weights had increased substantially, mainly due to bigger boilers. The main problems were with the small bridges used for cattle creeps, occupation crossings etc. This was the reason why the Royal Scots and the Coronations were banned from the Settle and Carlisle. Until a lot of the smaller underbridges were rebuilt in the 1930's the larger new LMS locos couldn't use that route.

 

Jamie

[APOLLO]

The Tay bridge and Dee Bridge (Chester) disasters spurred lots of engineering thought into railway bridge design. Lessons were learned the hard way.

 

I agree engineering has advanced tremendously over the years, the Airbus A380 is an engineering marvel in my eyes.

 

Brit15

[RJS1977]

Engineering is about doing the minimum to meet the specified requirements.

 

 

Reminds me of the story that Colin Chapman (founder of the original Lotus F1 team) used to be disappointed if his cars didn't fall to bits on the slowing-down lap after the race because to his mind it meant they were over-engineered and therefore too heavy!

[John_Miles]

This is the M6 motorway viaduct over the railway, river and canal at Gathurst near Wigan.

 

 

Those concrete pillars have recently been extensively repaired due to concrete spalling and rusting steel reinforcing. God knows whats going on deep inside them. The steelwork deck may be well engineered but the supports won't last a lot longer - certainly not 178 years.

 

Brit15

If that steel deck is not painted regularly, it has no chance of lasting any great length of time.

 

Masonry structures last so well because they use compressive forces only (i.e. all the components are pushing against each other) and there are no components which corrode. They are built from essentially naturally occurring and inert materials. The arguments about them being over-engineered are interesting. I suspect that if you did the calculations you would find that the largest load on them is their own weight and the added weight of what they are carrying is small by comparison so possibly they are not over-engineered. It is a long time since I did any bridge design (40 years) but I recollect that for a typical beam bridge, its self-weight is around 80% of the total load, hence my thoughts about masonry structures.

[96701]

The problem is that said "bean counters" don't understand that a well engineered solution generally won't have anything to shave off without compromising its ability to work as intended.

 

The other side of that is that if we used Victorian margins these days we would be able to do about 15% of the laughably inadequate infrastructure projects that we do in this country.

How many laughably inadequate infrastructure projects have the British done?

[Silver Sidelines]

A number of thoughts come to mind .

 

Waterproofing for example of viaduct and bridge decks.  No matter how good the outer stonework there is no place for water inside the structure and keeping drains unblocked and waterproof membranes intact requires regular maintenance which in the present era is often neglected.  A lot of masonry / stone stuctures are hollow with perhaps lightweight fill in the voids.  If the fill material is allowed to saturate, and then freeze all manner of damage can result including spalling of the outer masonry leaf - perhaps as at Wigan.

 

As to the strength of masonry arches I would point you in the direction of a fellow Leeds University student, Bill Harvey, late of Dundee University and most recenlty a professor of Engineering at Exeter University.  His team has visited Dumfries and Galloway on two occasions to overload (and fail) redundant railway overbridges on the old Port Road.  I cannot lay my hands on the detail but my recollection is that the bridges were exceedingly robust and took a lot to demolish.

 

Ray