Bristol connections: Metro, Bus Rapid Transit, PTE, ITA and local councils - discussion

[whole diary]

[TonyK]

Stapleton Road Bridge was damaged during the war and only temporary repairs were ever carried out.It always had a speed restriction on it.

Aha! An explanation that makes sense, and presumably explains the sort of strapping pieces welded over the top of the bridge.

Rooke, welcome to this forum, and thank you for the insight!

[stuving]

Aha! An explanation that makes sense, and presumably explains the sort of strapping pieces welded over the top of the bridge.

I rather doubt that - the ties are there to prevent buckling. Ignore the lattice design and think of it as a square U-shaped channel, made of cardboard if that helps. If the sides fold in or out they stop supporting the deck, and the tie stops that happening. However, there is also a buckling mode where both sides go the same way - one in, one out - and to prevent that the joint of the tie to the sides has to be stiff. And, as you can see using Streetview, they are. In fact it is a pretty common bridge design, especially in the USA.

[Red Squirrel]

Aha! An explanation that makes sense, and presumably explains the sort of strapping pieces welded over the top of the bridge.

I rather doubt that - the ties are there to prevent buckling. Ignore the lattice design and think of it as a square U-shaped channel, made of cardboard if that helps. If the sides fold in or out they stop supporting the deck, and the tie stops that happening. However, there is also a buckling mode where both sides go the same way - one in, one out - and to prevent that the joint of the tie to the sides has to be stiff. And, as you can see using Streetview, they are. In fact it is a pretty common bridge design, especially in the USA.

If further evidence were needed, here's a 1918 photo with the struts in situ:



I really rather like this viaduct, with all its rivets, struts and gusset plates; don't know what it's done to offend FT, N!

Welcome, Rooke, and thanks for your contribution.

[TonyK]

I really rather like this viaduct, with all its rivets, struts and gusset plates; don't know what it's done to offend FT, N!

Welcome, Rooke, and thanks for your contribution.

Not just me it offended, Red Squirrel, but my ancestor Four Track, Then! Its major crime was to stop carrying railway traffic. But I don't think it a thing of total ugliness, it just doesn't look to my untrained eye to have been done in one go.

I'm grateful for the early picture, which settles the argument for me - it obviously was built that way. Normally, one would expect a properly designed, built, and maintained railway bridge to last more than a century. Before I level accusations at the designer or builder, though, I decided on a bit of internet research. There are two events that seem to have possible relevance: the nearby gas works was bombed by the Luftwaffe, and apparently something moved in the bridge during the long hot summer of 1976. Either, or neither, of these events could have been the beginning of the end for the bridge. Maybe it was just a reluctance to spend money on it in the 1980s, against a picture of decline in the railways?

If those struts are truly essential for the integrity of the bridge, then it is doomed. You would never fit OHLE under them. I am in the area at least one day weekly, and will watch with great interest. Having watched remotely the goings on at Reading, and other events like the demolition of Mumps Bridge in Oldham ("The home of the Tubular Bandage"), I can see that this will be a major job for a project manager, with homes, businesses, roads, and a busy railway all around. I wonder whether it would be useful to lay an extra track to the station, just for demolition and construction traffic to use?

I look forward to hearing from an Industry Insider.

[stuving]

... it just doesn't look to my untrained eye to have been done in one go.

You could still be right about the overhead ties being an afterthought. I checked on their correct name, which is sway bracing - as that's their other main function. It would not be so unusual to add them to a bridge if it was found to sway too much. ("Sway" here means twisting, not moving sideways.) With two tracks over it, the load is always off-centre, which may be relevant.

Most bridges have sides high enough that this bracing goes between them, otherwise it can go on the sides. So ones like this are not, actually, that common. I know I've seen examples, but can't now remember where.

PS: If you look underneath the bridge via Streetview, you can see that there is sway bracing on the sides too. That also looks a bit like an add-on, though it's hard to tell with riveted girders. Do we know when it was built?

[Red Squirrel]

According to the Bristol Railway Archive (BRA) the line was quadrified in 1888 (see http://bristol-rail.co.uk/wiki/Stapleton_Road_Viaduct), so it seems reasonable to assume the truss viaduct was built then. The BRA also point out that the Froom used to run right past the M32 end of the viaduct, so I wonder if the diversion of this river had anything to do with the truss viaduct's alleged structural problems. I say 'alleged' because the viaduct was comdemend at a time when BR^▸ (British Rail(ways)) were looking for any old excuse to close down chunks of infrastructure; has it been surveyed since?

The BRA, I am pleased to see refer to the truss viaduct's tatty stone precursor as 'much patched-up and strengthened' 

I still claim they're 'struts', by the way - I think a sway brace is an angled strut, though I'd concede that the struts may be sufficiently stiff to obviate the need for braces.

[JayMac]

http://bristol-rail.co.uk/w/images/thumb/d/d0/Stapleton_Road_Viaduct3.jpg/450px-Stapleton_Road_Viaduct3.jpg

Always wondered about this embellishment. Appears not to serve, and never to have served, any purpose whatsoever. Other than decoration. One wonders why this small folly was included in the building of the B&SWUR.

[TonyK]

A Gothic remnant of a grander building from a grander time.

[JayMac]

A Gothic remnant of a grander building from a grander time.

You are Kevin McCloud and I claim my ^5.

[Red Squirrel]

A Gothic remnant of a grander building from a grander time.

I should probably research this better, but I seem to remember my Dad telling me it was a night watchman's shelter - pre-dating the institution of the police, and therefore pre-dating the station.

[Chris from Nailsea]

Hmm.  Picking up on Red Squirrel's post, is it possible that it's some form of ventilation / access for the diverted River Frome, which runs underground for much of its course through Baptist Mills?

[ellendune]

Hmm.  Picking up on Red Squirrel's post, is it possible that it's some form of ventilation / access for the diverted River Frome, which runs underground for much of its course through Baptist Mills?

Except that in the Stapleton Road Area the river was not culverted, as far as I can tell, until the M32 was built - and that  building is much older.

[Red Squirrel]

From FOSBR^▸ (Friends of Suburban Bristol Railways):

Greater Bristol Metro Campaign
Four Tracks and Local Electrification

Department for Transport (DfT^» (Department for Transport - about)) funding to re-instate the missing two tracks between Temple Meads and Filton Abbey Wood Stations is essential for the Bristol Metro. The decision is expected in June 2013.

MPs^▸ (Member of Parliament), the Mayor of Bristol, local councillors, trade unionists, transport campaigners and passengers are invited to join FOSBR:-

When ?   Friday 17 May 2013      11.00 ^ 11.30

Where ?   Stapleton Road Station^s new footbridge

Why ?   To show local support for funding 4 tracks and local
                   Electrification, because: 

o Four tracks would allow more trains, more often to: Avonmouth, Sea Mills, Shirehampton, Bridgwater, Bedminster, Clifton Down, Filton Abbey Wood, Keynsham, Lawrence Hill, Nailsea, Oldfield Park, Parson Street, Trowbridge, Weymouth, Worle, Yate and Yatton stations. 

o Four tracks would allow the nine million passengers who arrive at Temple Meads Station each year to continue their journey by train to local stations throughout the North Bristol conurbation.

o Four tracks would provide the one million passengers who use the Avonmouth line with a thirty minute service.

o Four tracks would reduce the current conflict between local and long distance trains and allow cross Bristol services.

o Four tracks work and local electrification must be carried out during the electrification of the Great Western Main line (which has now started), or the opportunity could be lost for a generation.

o Local electrification and four tracks will convert Bristol^s Beeching era relic into a modern electric suburban network.

o Four tracks would enable the north Bristol circular route, building the case for returning the Severn Beach Line to two tracks as far as Avonmouth and a fifteen minute interval service.


Four tracking is needed from Bristol Temple Meads to Filton Abbey Wood

I hope to be there.

Re-Quadrify, Imminently!

Edit: I assume Montpelier wasn't omitted deliberately!

[TonyK]

Sadly, I can't be there. By cruel irony, I shall be adjacent to Shirehampton station at that time. I can spare the ^3.00, but not the time. Please give everyone there my compliments and best wishes.

Requadrify, Imminently, eh? Don't know where you think of such ideas.

Four Track, Now!

[ellendune]

So is FTN now RqI

FTN = Four Track Now
RqI = Requadrify Imminently