East West rail, Bletchley to oxford line

[cheesysmith]

Don`t mistake design life and design loadings as a mistake. The original structure was not designed to carry the loads that the new one is. As to over engineered, the fact it has stood for so long without maintenance says good things about the original design. I don`t think we could afford to build things like bridges to the Victorian over engineered standards now. As for the forth bridge situation, the fault is not in the design or the build of the bridge, the fault is with those who ordered it, in what they specified the bridge to take. otherwise known as the treasury going for the cheapest option.  

 

If you want to know about poor bridge design, look up the M1 viaduct at tinsley/meadowhall and compare it to the Australian original design.

[KingEdwardII]

1 hour ago, cheesysmith said:

the fault is with those who ordered it, in what they specified the bridge to take. otherwise known as the treasury going for the cheapest option.

I can agree with that - it takes the government to make a real cock-up. And they are past masters at penny-pinching, for which we all pay very dearly. The irony with the Forth & Severn bridges is that they both made loads of money from the tolls and so could have afforded a more expensive construction in the first place.

 

Yours,  Mike.

[Edwin_m]

Masonry bridges are generally over-engineered by definition.  They use only compressive forces, and stone is immensely strong in compression. With some fairly minimal maintenance and as long as the supporting ground doesn't move, these can last almost indefinitely - there are many road bridges still around that predate the railway age.  Unreinforced concrete bridges, such as those of "Concrete Bob" on the West Highland, are similar in structural behaviour to masonry.  

 

Not all Victorian bridges were over-engineered  though - thinking of the cast iron ones in particular.  Most of those aren't around today, simply because they proved to be inadequate or in some cases collapsed.  

 

Steel or reinforced concrete carry tension forces in various parts of the structure, and these are present in most bridges made of those materials.  Thus the bridge has to be designed based on structural analysis, and this depends on the loads it has to carry.  Thus they can become inadequate if the loads increase, or some unexpected deterioration reduces the strength of the material.  The latter has happened to many reinforced concrete bridges from the middle of the 20th century, when use in tension was fairly new and long-term behaviour wasn't well understood.  Hopefully we know a bit better these days!  

[Nearholmer]

Before work began, the Bletchley-Bicester line was a case study in bridge failure modes, mostly where the ground had slowly shifted, taking bits of bridge with it, to create cracks of various kinds. Parapets are a special case, of course, because the design impact loading has changed over the years from ‘virtually nothing’ to ‘speeding lorry’.

[Bernard Lamb]

7 hours ago, KingEdwardII said:

Wisely so, as it turns out.

 

"Plan for success" is the principle - over-engineer for the reason that the usage will well exceed original expectations. Penny-pinching usually leads to tears.

 

This was not done in the 1960s and we paid the price by having to redo major structures within 50 years (sometimes less). I'm thinking of the initial suspension bridges over the Severn Estuary and the Firth of Forth, for example. Traffic was higher than anticipated (surprise, surprise) and there were continual maintenance problems - result, 2 new bridges less than 50 years after the original ones. The expensive widening of the M25 for the 2012 Olympics is another - the original construction was criticised at the time for being too small for the likely traffic. Goodness only knows how much more was eventually paid out to build something closer to what was required.

 

Just as well Bazalgette built the London sewers on this principle - it is only in very recent times that the sheer volumes involved with a hugely expanded city have finally necessitated a major expansion.

 

Ah well, it keeps the construction boys busy!!

 

Yours,  Mike.

It is rather more complicated than that.

AFAIK the design was to the laid down specification in both cases, which made certain assumptions. With hindsight it is easy to say that traffic volumes would increase. However on the Severn bridge it was not just the volume, but the proportion of that volume that comprised HGVs. Much higher than the original estimates. This extra load caused cracks to appear in the box girders under the roadway. The area immediately under the area where the wheels of the HGVs run required extensive alterations and repair to the welds. For the technical reader fillet welds were replaced with part penetration welds. I worked on ultrasonic weld testing and this was an oft quoted example. Goodness only knows how much has been spent on repairing these box girders. 

On the Forth bridge there was some concern expressed about corrosion in the cables. These were tested and checked at various times and after dehumidifiers were installed it was accepted as needing no further urgent work.

It is easy to be critical when not fully informed as to the the reasons why certain decisions were made.

I remember a comment by Nicholas Pevsner, actually about bridges on the M1, where he described them as looking as though they would last forever and then saying that permanence was not a good attribute in a structure that was to do with transport.

Bernard  

[Pacific231G]

2 hours ago, Edwin_m said:

Masonry bridges are generally over-engineered by definition.  They use only compressive forces, and stone is immensely strong in compression. With some fairly minimal maintenance and as long as the supporting ground doesn't move, these can last almost indefinitely - there are many road bridges still around that predate the railway age.  Unreinforced concrete bridges, such as those of "Concrete Bob" on the West Highland, are similar in structural behaviour to masonry.  

 

Not all Victorian bridges were over-engineered  though - thinking of the cast iron ones in particular.  Most of those aren't around today, simply because they proved to be inadequate or in some cases collapsed.  

 

Steel or reinforced concrete carry tension forces in various parts of the structure, and these are present in most bridges made of those materials.  Thus the bridge has to be designed based on structural analysis, and this depends on the loads it has to carry.  Thus they can become inadequate if the loads increase, or some unexpected deterioration reduces the strength of the material.  The latter has happened to many reinforced concrete bridges from the middle of the 20th century, when use in tension was fairly new and long-term behaviour wasn't well understood.  Hopefully we know a bit better these days!  

I've recently been admiring the Wharncliffe Viaduct (which is just about within walking distance of my house) and it looks almost archaeological - like some ancient temple.  When it was widened from two (originally BG) to four tracks there must have been a temptation to build a more modern and presumably cheaper structure alongside Brunel's original - fortunately the GWR's aesthetic  sense  must have prevailed (It's only just struck me that Maidenhead Bridge would also have been widened at some stage) 

 

BTW Isn't Verney Junction somewhere near Grandborough Junction ? I've seen a rather nice model of that!

 

 

[Nearholmer]

10 minutes ago, Pacific231G said:

BTW Isn't Verney Junction somewhere near Grandborough Junction ? I've seen a rather nice model of that!

 

If you really want to know, here is my thread that attempts reconcile the real and imaginary geography of The Buckingham Branches. 

 

[Pacific231G]

On 18/12/2021 at 19:30, Nearholmer said:

 

If you really want to know, here is my thread that attempts reconcile the real and imaginary geography of The Buckingham Branches. 

 

It's a thread well worth revisiting Kevin and I'm still fascinated by the once very real prospect of a GCR/Met terminus at no 8 St. Clements High Street Oxford,  even though it would have destroyed the Mesopotamian peace of Parson's Pleasure and Dame's Delight (But it was more close to having really existed than Peter Denny's direct trains from Oxford to the cathedral city of Buckingham).  Were I into British modelling I think that would be my "Minories". I also rather liked Peter Denny's reason for choosing the GCR. It was apparently because the MRC was full of GWR enthusiasts who'd instantly and noisily criticise any departure he made from the prototype but few people then knew anything about the GCR so he could develop his modelling of it in peace. It also had solid rather than lattice signal posts which would be easier to model. On such small matters are great works founded. 

Edited December 19, 2021 by Pacific231G
missing word

[Northmoor]

3 hours ago, Edwin_m said:

Not all Victorian bridges were over-engineered  though - thinking of the cast iron ones in particular.  Most of those aren't around today, simply because they proved to be inadequate or in some cases collapsed.  

There's also the consideration that an iron bridge has a scrap value which often made them worth removing, regardless of actual condition.  A masonry bridge was just potential rubble.

[Nearholmer]

1 hour ago, Pacific231G said:

GCR/Met terminus at no 8 St. Clements High Street Oxford

 

Yes, if only the weather was better and the days longer, I could do a bke ride photo essay from Qauinton Road along the projected route of the O&AT into Oxford. Not one for this time of year though.

 

My scheme for that terminus was to represent it in 0 scale, assuming that it lingered-on as a tramway into the 1950s, rather as the W&U did. I got as far as buying a 4W railbus, plus a diesel shunter to haul the goods trains, and had it all plotted out, but then decided that it was too much of a diversion from coarse-0, and sold the motive power.

[KingEdwardII]

2 hours ago, Bernard Lamb said:

With hindsight it is easy to say that traffic volumes would increase.

I think that in the 1960s, it was a bl*&^%y cert - a one way bet. You didn't need much hindsight. The bridges were underspecified as a result. A very expensive mistake, as it turned out. The same was true of the M25 - it was built with insufficient capacity and this was pointed out long before it was completed.

 

I quite deliberately compared this against Bazalgette and the London sewer system - he clearly had the foresight to understand that London would get bigger and spent wisely on an "overspecified" system. I think that the eventual growth of London might have astounded even him, but most of the system he created is still going strong. Engineering at its best.

 

Thankfully, the replacement bridges look much better - the second Severn crossing both provided much needed additional capacity plus dealt with the crosswind issue. Still has some issues with ice formation in freezing damp weather, though, not unknown next to the sea...

 

Yours, Mike.

[Edwin_m]

13 hours ago, KingEdwardII said:

I think that in the 1960s, it was a bl*&^%y cert - a one way bet. You didn't need much hindsight. The bridges were underspecified as a result. A very expensive mistake, as it turned out. The same was true of the M25 - it was built with insufficient capacity and this was pointed out long before it was completed.

 

I quite deliberately compared this against Bazalgette and the London sewer system - he clearly had the foresight to understand that London would get bigger and spent wisely on an "overspecified" system. I think that the eventual growth of London might have astounded even him, but most of the system he created is still going strong. Engineering at its best.

 

Thankfully, the replacement bridges look much better - the second Severn crossing both provided much needed additional capacity plus dealt with the crosswind issue. Still has some issues with ice formation in freezing damp weather, though, not unknown next to the sea...

 

Yours, Mike.

However, it's fairly well known in transport planning circles that if you build a bigger road you just end up encouraging more traffic.  The congestion ends up just as bad as before, there is more pollution and the public transport alternative is less viable because fewer people are using it.  This doesn't really happen with building railways because the number of trains is managed and if done properly that keeps it at a lever where everything still runs smoothly.  

[cctransuk]

9 minutes ago, Edwin_m said:

However, it's fairly well known in transport planning circles that if you build a bigger road you just end up encouraging more traffic.  The congestion ends up just as bad as before, there is more pollution and the public transport alternative is less viable because fewer people are using it.  This doesn't really happen with building railways because the number of trains is managed and if done properly that keeps it at a lever where everything still runs smoothly.  

 

Traffic does not need encouraging - it will expand quicker than Covid Omicron anyway!!

 

CJI.

[dibber25]

23 hours ago, KingEdwardII said:

I think that in the 1960s, it was a bl*&^%y cert - a one way bet. You didn't need much hindsight. The bridges were underspecified as a result. A very expensive mistake, as it turned out. The same was true of the M25 - it was built with insufficient capacity and this was pointed out long before it was completed.

 

I quite deliberately compared this against Bazalgette and the London sewer system - he clearly had the foresight to understand that London would get bigger and spent wisely on an "overspecified" system. I think that the eventual growth of London might have astounded even him, but most of the system he created is still going strong. Engineering at its best.

 

Thankfully, the replacement bridges look much better - the second Severn crossing both provided much needed additional capacity plus dealt with the crosswind issue. Still has some issues with ice formation in freezing damp weather, though, not unknown next to the sea...

 

Yours, Mike.

Back when they were building the last bits of the M25 past my 'home town' (Chertsey-Runnymede and Yeoveney-Poyle) I was one of the journalists invited to come and look at work on the rail-over-motorway bridge at Lyne and the Runnymede bridge over the Thames. One of the things we were told was that the ONLY section that MIGHT need to be four lanes EVENTUALLY was Chertsey-Heathrow. It was fortunate that the surfacing on that section was initially a cock-up because, when they re-did the surface on the three lanes, they were able to add the fourth at the same time! 

[KingEdwardII]

10 hours ago, Edwin_m said:

This doesn't really happen with building railways because the number of trains is managed

I can't agree with that, having experienced the "standing all the way" rush hour trains between Winchester and Waterloo over the years (pre-Covid, naturally). Those are the equivalent of road congestion, except that you are paying a princely sum for the privilege, since the rush hour prices are the highest. 

 

On the railways in the current era, one of the problems is the inflexibility of fixed-formation multiple units. So the main group of EMUs for Weymouth/Bournemouth/Southampton - Waterloo services are 5 carriage sets, with 10 carriages (2 sets) being typical for rush hour trains. The stations (mostly) can actually handle 12 carriage trains, but adding 1 carriage to each 5 car set is beyond the capability of man, it seems. The same is true for Cross-Country services, some of which are ludicrously short and get to sardine can status at times.

 

As for roads, one of the huge failings in the UK relates to the way we build major road junctions, which cause horrendous congestion where there need be none. The use of roundabouts for major junctions is little short of insane, typically capped off by adding lights, which simply make the congestion worse. The M2/A2 junction in Kent, west of Canterbury is a classic of this kind - I've queued for over 2 miles there in a random mid-morning journey (i.e. not even rush hour). Why do we build things this way??

 

Yours, Mike.

[Nearholmer]

2 minutes ago, KingEdwardII said:

since the rush hour prices are the highest. 

 

Unless, like most of those with whom you are crushed-in, you have a season ticket, in which case they are significantly lower.

 

Railways can suffer from an excess of "build it and they will come" syndrome, just as roads can, and it can be very costly to add capacity by running more, and/or longer trains. The economics of doing so get particularly painful if the load is very peaky; the marginal cost of adding capacity at peaks can be huge, which is why railways tend to be reluctant to do it unless they really have to. Its better from an econmic standpoint to attempt to flatten and spread the peak, because the marginal cost of adding capacity is low, using techniques including high fares during the peak .........

[KingEdwardII]

12 minutes ago, Nearholmer said:

Unless, like most of those with whom you are crushed-in, you have a season ticket,

Yes, season tickets are certainly cheaper than buying individual tickets for each journey, if you're travelling every day. Of course, it looks a bit different when you have to consider taking out a mortgage or handing over your first born in order to buy one. The current annual season ticket from Winchester to London is £5,580 (without London bus/tube). Out of taxed income, that is a lot of cash. 

 

Thankfully, I never had to commute - my place of work was in the beautiful Hampshire countryside only 5 miles from home. My journeys were for specific meetings and conferences in London - so, no season ticket but prices high enough to require consideration in the departmental budget - with no first class! Current anytime return is £76.80. When you've paid that, you're inclined to be rather miffed if you can't get a seat for an hour long journey, even if it's on expenses.

 

My tactic was to arrange London meetings to start later, which became more effective over the years as my seniority increased, so that I could travel by trains that had seating available. Conferences and such like were a different matter.

 

It is easy to understand the relish the commuting classes have for the Covid "Zoom world" - no huge outlays and the chance to stay an extra hour in bed! That will do nicely, thank you! (My elder son and his partner are both part of that world).

 

Yours, Mike.

[Northmoor]

29 minutes ago, KingEdwardII said:

Yes, season tickets are certainly cheaper than buying individual tickets for each journey, if you're travelling every day. Of course, it looks a bit different when you have to consider taking out a mortgage or handing over your first born in order to buy one. The current annual season ticket from Winchester to London is £5,580 (without London bus/tube). Out of taxed income, that is a lot of cash. 

 

Thankfully, I never had to commute - my place of work was in the beautiful Hampshire countryside only 5 miles from home. My journeys were for specific meetings and conferences in London - so, no season ticket but prices high enough to require consideration in the departmental budget - with no first class! Current anytime return is £76.80. When you've paid that, you're inclined to be rather miffed if you can't get a seat for an hour long journey, even if it's on expenses.

 

My tactic was to arrange London meetings to start later, which became more effective over the years as my seniority increased, so that I could travel by trains that had seating available. Conferences and such like were a different matter.

 

It is easy to understand the relish the commuting classes have for the Covid "Zoom world" - no huge outlays and the chance to stay an extra hour in bed! That will do nicely, thank you! (My elder son and his partner are both part of that world).

 

Yours, Mike.

Commuting full-time, that's 19 pence per mile.  You would have to drive a seriously cheap and economical car to match that , and it probably wouldn't last very long at that kind of weekly mileage.  It is an oddity though that because people spread it through the year, topping up the tank every week, people treat car use at twice that cost per mile as perfectly acceptable.

 

However, in general I agree with you; ten years ago, I always tried to get London meetings to start after lunch as the Up trains were empty and the fare (expenses claimed from the taxpayer) were cheaper. Pre-COVID, I commuted from Brookwood to Waterloo daily;  I got a seat in the morning at least 95% of the time and at least 99% of the time in the evening.  I did however see some very strange behaviours; people who got into half-full carriages and stood by the doors, presumably so they didn't have to sit next to anyone.  I saw so many squeeze into the front carriages and stand from Woking, while in carriage 11 or 12 I had a pair of seats to myself.  No doubt all these people moaned to anyone who would listen (and many who wished they didn't have to) that they could never get a seat.

[phil-b259]

1 hour ago, KingEdwardII said:

 

On the railways in the current era, one of the problems is the inflexibility of fixed-formation multiple units. So the main group of EMUs for Weymouth/Bournemouth/Southampton - Waterloo services are 5 carriage sets, with 10 carriages (2 sets) being typical for rush hour trains. The stations (mostly) can actually handle 12 carriage trains, but adding 1 carriage to each 5 car set is beyond the capability of man, it seems. The same is true for Cross-Country services, some of which are ludicrously short and get to sardine can status at times.

 

 

Please remember that those 5 car 444 units (and the 442s before them) are based on the 23m long Mk3 coach while the slam door Mk1 based EMUs and the 450s are only 20m long!

 

A 10 car train made up of 23m carriages is more or less the same length as a 12 car made up from 20m long stock.

 

If you add a carriage to a 5 x 23m unit then two units coupled won't fit in many of the platforms - including their London terminus at Waterloo which is impossible to expand to any significant degree!

 

Similalrly adding an extra coach to a 4x20m unit means you are stuck with a maximum of 2 units as 15 x 20m won't fit into platforms either!

 

As for XC, we have explained this hundreds of times before on various threads!

 

They need to be able to platform share at key hubs (e.g. Birmingham New Street) or fit into short bay platforms (e.g. Reading). Making the XC units any longer than 5 cars means they don't fit and thus you cannot run as many trains because they need to have sole occupancy of long platforms. In other words the choice is either a couple of long trains a day (probably at inconvenient times) or lots of short ones - but its well proven that if you want to attract passengers to rail, a frequent service is extremely important.

[KingEdwardII]

On 18/12/2021 at 16:57, Edwin_m said:

Not all Victorian bridges were over-engineered  though - thinking of the cast iron ones in particular. 

I think that is/was more a matter of not fully understanding the material concerned, rather than getting the engineering wrong.

 

I suppose that is true of the early reinforced concrete structures also.

 

Less so for steel construction such as the Severn & Forth suspension bridges, since by that time, steel had a long history of use in many contexts, including suspension bridges.

 

And then there were Victorian structures most certainly done 'on the cheap" - Brunel's wooden viaducts in Cornwall (and elsewhere) are a classic case. Most of these had to be replaced after a relatively short lifespan. Another case of unwise pennypinching.

 

Yours,  Mike.

[Edwin_m]

9 hours ago, KingEdwardII said:

I can't agree with that, having experienced the "standing all the way" rush hour trains between Winchester and Waterloo over the years (pre-Covid, naturally). Those are the equivalent of road congestion, except that you are paying a princely sum for the privilege, since the rush hour prices are the highest. 

It's a bit different though.  Adding more passenger capacity in the form of longer or more trains, as long as it doesn't hit performance, leaves the journey time unchanged.  

 

On a road, adding capacity temporarily reduces the journey time because it eliminates congestion.  This causes people who previously didn't travel or used public transport to switch to car, so the journey time goes back to about what it was.  

7 hours ago, KingEdwardII said:

I think that is/was more a matter of not fully understanding the material concerned, rather than getting the engineering wrong.

 

I suppose that is true of the early reinforced concrete structures also.

 

Less so for steel construction such as the Severn & Forth suspension bridges, since by that time, steel had a long history of use in many contexts, including suspension bridges.

 

And then there were Victorian structures most certainly done 'on the cheap" - Brunel's wooden viaducts in Cornwall (and elsewhere) are a classic case. Most of these had to be replaced after a relatively short lifespan. Another case of unwise pennypinching.

 

Yours,  Mike.

It's perhaps a different way of saying the same thing.  If you don't understand the material you need to allow greater margins of safety.  Even with steel there were new construction techniques and, because they were new, nobody really knew how well they would stand up over time.  

[KingEdwardII]

1 hour ago, Edwin_m said:

leaves the journey time unchanged.  

Standing up all the way just makes it feel like it takes forever 

 

Having to stand on a regular basis certainly also makes folk look for alternative ways of travelling. I've never (yet) had to stand in my car, although I may have come close to getting tossed out of the door on occasions . The prospect of having to stand on a lengthy rail journey like Winchester to Manchester or Newcastle would have me searching the airline websites...

 

BTW, I don't really accept this idea that adding capacity to the roads just leads to additional traffic and congestion as bad as it was before. Despite the grousing, the M25 has vastly improved journeys that involve getting from one side of London to the other, compared with what was available before. We have regularly travelled from Hampshire to Suffolk to visit relatives, since before the M25 was completed. The journey today is way better than before the M25 was completed - and the width expansion for the 2012 Olympics made things significantly better. Similarly, the A34 improvements have made journeys from Hampshire to the Midlands and the North much speedier and more reliable than before.

 

Equally, on the trains, capacity improvements can make a vast difference. On the Portsmouth - Cardiff route, the trains have gone from 2 carriages to 3 carriages and now to 5 carriages (at least for the busiest trains). This has more or less eliminated the problem of getting a seat. We just need equivalent targeted improvements on other routes.

 

Yours, Mike.

[2E Sub Shed]

On 18/12/2021 at 20:05, Northmoor said:

There's also the consideration that an iron bridge has a scrap value which often made them worth removing, regardless of actual condition.  A masonry bridge was just potential rubble.

Brackley Great Central viaduct went for hardcore to Milton Keynes according to web sources.

 

Although I seem to recall at the time it was reported (late 70's),  that it was for recovery of the engineering blues (bricks) used in its construction, but  cannot find any reference to confirm that, unless it was for hardcore rather than recycling as bricks.

[KingEdwardII]

54 minutes ago, 2E Sub Shed said:

it was for recovery of the engineering blues

The GWSR raided the remaining platforms along the Bicester - Bletchley section for the engineering blues before those platforms were obliterated as part of the current East-West works. With permission, of course.

 

Recycling at its best - what would otherwise have been landfill will find a good use in authentic re-creation on the GWSR and the GWSR get a valuable "free" resource, although with a lot of hard labour on the part of the volunteers.

 

Yours,  Mike.

[KeithHC]

Plus the GWSR have used recovered bricks from elsewhere. Including from the Tewksbury area and Avonmouth docks.

 

Keith