Bridge that Gap: Great Central Railway News

I'm not a bridge engineer, but I'd have thought it would have cost more than £500,000 to completely replace the 5 bridges to Broadway....

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But I don't understand your wish to establish a general principle. Won't any railway spending hundreds of thousands look at the cost of all the alternatives? Sometimes repair will be more economical, sometimes replacement.

 

Sticking with the GCR project, having carried out a detailed assessment of the bridge over the canal, they have clearly decided that it is best to renovate the existing bridge as that is the intention next year. It is also preserving a historic structure, which can only be a Good Thing in my view.
It will be interesting to see whether it is repaired in situ or craned out, refurbished and put back. I can see benefits both ways. Easier access to the metalwork on 'dry land' and to the masonry with the bridge out, but the extra cost of cranage involved (unless it's within the capability of the rail-mounted steam breakdown crane).

Andy

 

General principle? Whatever... do you mean?

I'll put it to you. In terms of engineering, what would you think would cost more? A short bridge, or a valley spanning viaduct?
A small house? Or a whopping mansion?

 

In post #618, you seemed to be asserting a principle along the lines of:

It's generally cheaper to replace old railway bridges than repair them.

I think this assertion is flawed. That's what I mean.

You then added to the principle by asserting that it applies to small bridges, but not large ones. Again, this makes no sense to me. The key factor is not size, but condition. (The Bluebell repaired Imberhorne viaduct, but how many of Brunel's Cornish timber viaducts did the GWR decide to rebuild rather than repair)? Railway companies will choose the option that works best financially, and that depends on condition.

If you want a general principle, may I offer:

Where it's cheaper to replace a railway structure than repair it, it should be replaced not repaired.

I'm reasonably confident this is a good guide, regardless of the size of the structure.

 

Whilst clearly that's the approach on the national network, I'm not sure it should always be the approach on a preserved railway. Retaining a historic structure built by the GWR or whoever which has 'steam age character', particularly if it is in full view of the passengers waiting on a station should come into the equation, even if more expensive. But again, each case must be examined on its own merits, with no 'one size fits all'.

Andy

 

Good point. I agree.

 

The Borders Railway reinstatement to Tweedbank (on the big railway) repaired / restored a lot of the remaining Victorian bridges and (I think) only built new structures where the originals no longer existed or required significant alterations due to a new alignment.

 

There are also the safety issues surrounding those crossing even rural roads which have become way busier since the days of common carrier rail freight. The recent Spa Valley hit-and-run highlights the issues and by no means all are to do with just headroom. As Andy says, no one size fits all.

 

Link to local rags online content with piece on the GCR canal bridge
nothing new but a nice picture of the bridge
http://www.loughboroughecho.net/news/local-news/great-central-railway-aims-renovate-13743748

Colin

 

Just found this in the Rail Engineer.
https://www.railengineer.uk/2017/10/13/reinstating-great-centrals-bridge-over-the-midland-main-line/

 

Another update on the bridge website...........
http://www.gcrailway.co.uk/unify/

 

For anyone who wasn't at last weekends GCR Gala, there were large numbers of "flyers" left on the trains and other locations regarding the canal bridge project.
The target they are aiming to raise is £500,000 and they hope to start work on this (assuming the money comes in) in Autumn 2018. They are hoping do do the work with the bridge "in situ" using modern repair/restoration techniques.
In addition to restoring the bridge, the balance of the money will go towards continuing the design work for the rest of the link.

 

Interesting video of the bridge and entire gap (not mine). Before you ask (and if you read the comments), the drone is being flown within the regulations.

 

Very interesting; thanks for posting that. The aerial views certainly gives a better idea of just what's involved.

One thing I noticed: the alignment of the yet-to-be-refurbished old bridge (across the river) seems to be such that the track coming off it is going to have to veer pretty promptly in order to miss the existing shed - it seems to be pointed straight at it, and it doesn't seem to be that far away....

Noel

 

Before I started that video I wondered whether, given the absence of a sound track from a drone, they would have spoilt it by adding totally irrelevant and distracting music. Yes they had. Why oh why? I could watch with the sound turned off, but then I would risk missing any commentary that might be included.

 

Really? Say for example the options are to either repair an elegant brick arch bridge, or to replace it with a modern metal bridge. Let's say that the latter is cheaper, but the difference in costs, while significant, is not insurmountably large. Every other bridge on the line is, like the one that needs replacing or repairing, a brick arch. The bridge is situated in such a position that it is viewable from a number of vantage points which are popular vantage points for both the general public on walks stopping to watch the trains go by, and enthusiasts wishing to get a picture. The heritage railway in question is either able to fund the more expensive repair option, or has a portion of the cost available and will be able to raise the remaining funds both from its operations and from a planned public appeal. In such a scenario, my hope and (depending on the railway in question) potentially expectation would be the railway would splash out the extra cash to take the course of action which is in sympathy with the rest of the railway's heritage, and is more aesthetically pleasing.

Yes, I know this is one specific example, but in situations such as this it is difficult to suggest what a general principle should be, as each case is individual and subject to so many unique combinations of variables. Ultimately whichever decision a railway takes could (and probably will) be subjected to criticism because various people will think other options are better, but ultimately it is down to the railway to decide how it feels it is best to allocate its finances, and whether it is better to save money on a more cost-effective solution, or to spend more to preserve the original infrastructure and character of the line

 

I agree. Have a look at posts #626 & #627. You'd need to read through the discussion over the previous page or so to understand the point I was making.

 

Ah yes, I get it now. That's the problem with massively long threads, sometimes you try to skim-read them because you don't want to have to read every word, but then you can misinterpret what you're reading or miss out on important points!

 

Interesting to note that they are using the line for commercial training for NR and other railway companies, rolling stock and civil. Great use of the line to build extra revenue!