Hornby R8008 Grand Suspension Bridge - Based on any particular prototype?

[TravisM]

I keep looking and admiring Hornby’s R8008 Grand Suspension Bridge but I’ve always thought it was based on a “what if” rather than a prototype, no matter how loosely.

 

As impressive suspension bridges are, they have several serious issues which probably rule them out for railways.  One would be that they are extremely limited on weight, and though modern bridges can carry large numbers of cars, buses and trucks, each are quite light in comparison compared to a 100+ ton locomotive and say a 8/9 coach passenger train or equal length freight train.  I just don’t think the suspender cables would be able to withstand the sudden weight in one hit.

 

Secondly, suspension bridges have a certain amount of lateral and vertical movement which would cause problems for a railway, especially in high winds.  I think that a bridge of this type would be only good for subway or light rail services, or possibly for Branch line, a small loco or 2/3 car DMU.

[andyman7]

Yes, it's a work of fiction, impressive as a 'toy model' but totally impractical from a real life bridge engineering viewpoint - a classic suspension bridge is not compatible with the loads imparted by railway trains. In the 1960s it came in a fully illustrated box that made splendid use of forced perspective to suggest that the contents were an order of magnitude larger than the actual model in the box. Either that or it's a very small ship... 

Edited December 15, 2021 by andyman7

[BernardTPM]

Actually if you look at the suspension mouldings they are not purely suspension cables as there are radiating members too. The Albert Bridge in London is a similar hybrid, though it didn't start that way.

There are some French railway bridges, like the Viaduc des Rochers Noirs that use a similar but not identical design.

Edited December 16, 2021 by BernardTPM

[Trog]

Is the Royal Albert bridge over the Tamar at Saltash not technically a suspension bridge?

 

Only IKB being IKB he suspended his bridge decks from arches rather than the more usual cables.

[giz]

9 hours ago, BernardTPM said:

Actually if you look at the suspension mouldings they are not purely suspension cables as there are radiating members too. The Albert Bridge in London is a similar hybrid, though it didn't start that way.

There are some French railway bridges, like the Viaduc des Rochers Noirs that use a similar but not identical design.

Also the Brooklyn Bridge.

[Michael Hodgson]

2 hours ago, Trog said:

Is the Royal Albert bridge over the Tamar at Saltash not technically a suspension bridge?

 

Only IKB being IKB he suspended his bridge decks from arches rather than the more usual cables.

His Clifton Suspension Bridge is supported from chains rather than cables.

There are different types of suspension bridge, Royal Albert is a bowstring suspension bridge.

 

The suitability or otherwise for railways isn't so much the load - that's a design question of how strong the components need to be, something that has to be considered for all bridges.  

Railways need a bridge to exhibit more rigidity and stability in winds and under load than a road bridge, they need to cope with hammer blow etc when running steam locos.  It is not acceptable for the track to be humped (or sagging!) in the middle, whereas that's not really an issue for cars.

[Steamport Southport]

3 hours ago, giz said:

Also the Brooklyn Bridge.

 

And Manhattan.

 

Which also has four tracks of subway trains.

 

https://en.wikipedia.org/wiki/Manhattan_Bridge

 

 

Jason

[phil-b259]

13 hours ago, BernardTPM said:

There are some French railway bridges, like the Viaduc des Rochers Noirs that use a similar but not identical design.

 

That looks more like a Cable Stayed Bridge!

 

https://en.wikipedia.org/wiki/Cable-stayed_bridge

 

Cable stayed bridges are far more rigid and are perfectly suitable for railway applications.

 

Such bridges are also now preferred for road applications too as their rigidity is beneficial in high winds and allows for better wind shielding to prevent HGVs being blown over. The problem with the design has traditionally been that the maximum span length has been limited compared to that which can be achieved by a true suspension bridge but modern materials and design techniques have successive closed the gap.

 

Thing is if Hornby wanted to then I reckon you could still modify the bridge to make it look more like a double cable stayed design and thus be more realistic.

 

 

Edited December 16, 2021 by phil-b259

[Legend]

I thought there was a thread on this before . I've certainly gleemed some information somewhere that this was based on an actual structure on the Stockton and Darlington line .  Of course it didnt have Princess Pacifics and full trains running over it at full speed , so I'm afraid this version is not at all appropriate for the railway depicted in any Hornby catalogues , but it does look impressive !

Edited December 16, 2021 by Legend

[RichardT]

19 minutes ago, Legend said:

somewhere that this was based on an actual structure on the Stockton and Darlington line . 

Yes: the 1830 railway suspension bridge from Stockton to Port Darlington (Middlesbrough). They quickly discovered that it wasn’t suitable and it was rebuilt. Rumour has it that the original abutments survive buried beneath the replacement.

 

See:

https://www.thenorthernecho.co.uk/history/11778931.worlds-first-worst-railway-suspension-bridge/
 

The resemblance is obvious:

But Hornby describing theirs as a “Grand Victorian” bridge is also incorrect - if anything it’s a “Grand Georgian” structure!

 

Richard

[Nearholmer]

There was a sprinkling of suspension bridges on French minor railway networks, a  few of which are now on either cycle routes or have velorail (pedal trolley) operations over them, but this one is still very firmly in proper railway service, and very spectacular https://fr.m.wikipedia.org/wiki/Pont_de_Cassagne The photo here doesn’t quite convey the situation, or the way the railway approaches it, down a gradient and round a pretty tight curve, at the edge of a ravine. It is well worth seeing!

Im not well-enough up on bridge terminology to know whether these bridges designed by Gisclard are properly described as ‘cable stayed bridges’ or ‘suspension bridges’, but I think both variants were invented by French engineers, Seguin having created the first ‘ordinary suspension bridge’ c1825, and both are known in France as ‘pont suspendu’.

 

 

 

Edited December 16, 2021 by Nearholmer

[BernardTPM]

14 hours ago, BernardTPM said:

There are some French railway bridges, like the Viaduc des Rochers Noirs that use a similar but not identical design.

 

1 hour ago, phil-b259 said:

That looks more like a Cable Stayed Bridge!

 

https://en.wikipedia.org/wiki/Cable-stayed_bridge

 

Cable stayed bridges are far more rigid and are perfectly suitable for railway applications.

Exactly and the GVSB has the cable stays too; look at the radiating diagonals. It is not a pure suspension bridge, despite the product name. As to whether that was by accident or design I do't know. I doubt the original product designer is still alive.

The Albert Bridge was originally just a cable stay bridge, though not a particularly rigid one.

Edited December 16, 2021 by BernardTPM

[Pacific231G]

1 hour ago, Nearholmer said:

There was a sprinkling of suspension bridges on French minor railway networks, a  few of which are now on either cycle routes or have velorail (pedal trolley) operations over them, but this one is still very firmly in proper railway service, and very spectacular https://fr.m.wikipedia.org/wiki/Pont_de_Cassagne The photo here doesn’t quite convey the situation, or the way the railway approaches it, down a gradient and round a pretty tight curve, at the edge of a ravine. It is well worth seeing!

 

 

This one on the Cerdagne line and the viaduc de Rochers Noir are both examples of Gisclard rigid suspension bridges*. They're a bit of a hybrid as the actual deck is suspended by vertical cables coming from the two main sets of cables but these are in turn supported by stay cables from the opposite tower.  

This isn't immediately obvious from photos as the vertical cables are actually supporting the deck from below but you can see that if you examine this photo of it closely

https://upload.wikimedia.org/wikipedia/commons/a/a8/Viaduc_des_Rochers_Noirs-1923.jpg

The two main cable sets are also firmly coupled at point O on this diagram so making for a far more rigid structures than a traditional suspension bridge or a simple cable stayed bridge.

I've been over both viaducts - though unfortunately, for the Rochers Noir, only by car and, when that was no longer allowed,  on foot as I was twenty two years too late to cross it by a train of the Tramways de Correze (the last of France's many public steam tramways to close) Since 2005 you haven't even been allowed to cross it on foot.

These were both metre gauge viaducts and I don't know if Gisclard's design was ever used for a standard gauge railway.

 

*In his paper in Annales des Ponts et Chaussées in 1899 Albert Gisclard does appear to refer to a rigid suspension bridge as being a contradiction though clearly his system was rigid enough. 

Edited December 16, 2021 by Pacific231G

[Nearholmer]

34 minutes ago, Pacific231G said:

These were both metre gauge viaducts and I don't know if Gisclard's design was ever used for a standard gauge railway.

From what I can work out, it wasn’t, but I’m not totally sure about the ones built ‘in the colonies’ or to restore river crossings in northern France after WW1. Some of the latter definitely had metre gauge across them.

 

Gisclard was killed when a muddle over brakes led to the runaway of part of the train that was being used to weight-test the Cassagne bridge, causing it to turn over on the bend, and on one of the occasions when I rode over it the train had to come to a screeching halt on the approach because rocks had fallen all over the track - I thought we were about to go the same way as he had!

 

 

 

 

Edited December 16, 2021 by Nearholmer

[Nearholmer]

[Pacific231G]

14 minutes ago, Nearholmer said:

Yes, despite his reference in his paper to it being a contradiction, he actually titled the paper "a new type of rigid suspension bridge". 

you can read it here. 

https://gallica.bnf.fr/ark:/12148/bpt6k6125610/f216.image

Edited December 16, 2021 by Pacific231G

[andyman7]

2 hours ago, phil-b259 said:

 

That looks more like a Cable Stayed Bridge!

 

https://en.wikipedia.org/wiki/Cable-stayed_bridge

 

Cable stayed bridges are far more rigid and are perfectly suitable for railway applications.

 

Such bridges are also now preferred for road applications too as their rigidity is beneficial in high winds and allows for better wind shielding to prevent HGVs being blown over. The problem with the design has traditionally been that the maximum span length has been limited compared to that which can be achieved by a true suspension bridge but modern materials and design techniques have successive closed the gap.

 

Thing is if Hornby wanted to then I reckon you could still modify the bridge to make it look more like a double cable stayed design and thus be more realistic.

 

 

My thinking is from the perspective that given that Triang items are ideally supposed to be generic steam-era structures, this really doesn't fit the bill. And it says in large letters on the box 'Grand Victorian Suspension Bridge' - not 'Grand Victorian Cable-Stayed Bridge'....

[The Johnster]

The other problem with using suspension bridges on railways is the vertical and horizontal movement under load and in crosswinds.  The 'Grand Victorian Suspension Bridge' is certainly not capable of carrying the trains Triang showed on it, and that ship is never going to get it's funnel under the deck at that stage of the tide, never mind the masts!  It is suitable as a minor road bridge like the Clifton, with a severe weight limit, or a footpath bridge.

 

I sometimes think that Triang, and more recent Hornby offerings, show a lack of understanding of what bridges are and how they work; there was a girder bridge offered in the 80s and 90s that simply hung in mid air, with no abutments.  All it did in engineering terms was to add to the load on the piers, with were several inches away on each side.  OTOH, Triang offered a brick arched bridge available as a single arch or a 3 arch viaduct, and a rather graceful river bridge with a decorated balustrade that were excellent models that would stand scrutiny even now. 

[BernardTPM]

1 hour ago, andyman7 said:

My thinking is from the perspective that given that Triang items are ideally supposed to be generic steam-era structures, this really doesn't fit the bill. And it says in large letters on the box 'Grand Victorian Suspension Bridge' - not 'Grand Victorian Cable-Stayed Bridge'....

Yes, but they've moulded it with both suspension and cable stay elements. Now it could just be a co-incidence but trains coming from Margate into Victoria would get a good view* of the Albert Brige which has both suspension and cable stay elements...

I'd agree though that it would be unlikely to be strong enough to carry a mainline railway.

 

Of course, the piers on their own could be used to produce a very different looking stucture, perhaps like Stephenson's box girders at Conwy or his (as built) Britannia Bridge.

 

* Chelsea Bridge (which is a suspension bridge) is closer but is obviously not Victorian.

[andyman7]

1 hour ago, The Johnster said:

The other problem with using suspension bridges on railways is the vertical and horizontal movement under load and in crosswinds.  The 'Grand Victorian Suspension Bridge' is certainly not capable of carrying the trains Triang showed on it, and that ship is never going to get it's funnel under the deck at that stage of the tide, never mind the masts!  It is suitable as a minor road bridge like the Clifton, with a severe weight limit, or a footpath bridge.

 

I sometimes think that Triang, and more recent Hornby offerings, show a lack of understanding of what bridges are and how they work; there was a girder bridge offered in the 80s and 90s that simply hung in mid air, with no abutments.  All it did in engineering terms was to add to the load on the piers, with were several inches away on each side.  OTOH, Triang offered a brick arched bridge available as a single arch or a 3 arch viaduct, and a rather graceful river bridge with a decorated balustrade that were excellent models that would stand scrutiny even now. 

The Girder Bridge dates back to the early 70s. The Girder elements are useful if mated to a decent set of abutments! The Brick Bridge, Viaduct and River Bridge survive today in the modern range and I agree they are useful - I have used the Viaduct with brickwork painted and coping stones all picked out and it looks splendid.

[jim.snowdon]

On 16/12/2021 at 11:43, Michael Hodgson said:

There are different types of suspension bridge, Royal Albert is a bowstring suspension bridge.

The Royal Albert bridge is, technically, a lenticular truss.

 

[jim.snowdon]

On 16/12/2021 at 11:43, Michael Hodgson said:

His Clifton Suspension Bridge is supported from chains rather than cables.

There are different types of suspension bridge, Royal Albert is a bowstring suspension bridge.

 

The suitability or otherwise for railways isn't so much the load - that's a design question of how strong the components need to be, something that has to be considered for all bridges.  

Railways need a bridge to exhibit more rigidity and stability in winds and under load than a road bridge, they need to cope with hammer blow etc when running steam locos.  It is not acceptable for the track to be humped (or sagging!) in the middle, whereas that's not really an issue for cars.

Suspension bridges were never suitable for steam locomotives, with their unbalanced forces, but there now examples of large suspension bridges carrying main line tracks. The localised deflection of the deck is quite marked, but that is all part of the inherent flexibility of suspension bridges.

 

[BR60103]

Niagara Falls Suspension Bridge - Wikipedia

 

Taking the Great Western over the Niagara River (also New York Central &c). Disappeared before anyone I met would hve seen it.

(won't post as link)

Edited December 18, 2021 by BR60103

[pH]

2 hours ago, BR60103 said:

Niagara Falls Suspension Bridge - Wikipedia

 

Taking the Great Western over the Niagara River (also New York Central &c). Disappeared before anyone I met would hve seen it.

(won't post as link)

Here’s the link:

 

https://en.wikipedia.org/wiki/Niagara_Falls_Suspension_Bridge

[phil-b259]

13 hours ago, jim.snowdon said:

Suspension bridges were never suitable for steam locomotives, with their unbalanced forces, but there now examples of large suspension bridges carrying main line tracks. 

 

But how many of those are true suspension bridges?

From what I can tell all ‘suspension bridges’ used by trains are actually hybrid structures where stiff deep deck structures and cable stayed elements are used to remove significant amounts of the flexibility which would otherwise be present.