Iron and Steel Bridges

This page is basically just images of real bridges!


Iron Arch Bridge

Made of cast iron, these were the earliest iron/steel bridges, and the first notable example is, of course, at Iron Bridge, and dates from 1779. They are the most attractive of iron bridges, but are fairly rare, and always seem to be built to take the railway over something, rather than taking something over the railway.

Manchester

There are two great example just west of Deansgate Station, one of which has three spans.



This image shows how multiple arches were used to provide strength. It is not easy to see, but where the arch meets the stonework, the stone is angled to be mor-or-less normal to the curve.

I cannot rember where this one was, Leeds maybe?





Truss Bridge

Truss bridges have girders across the span on two levels, these are the top and bottom chords, with ironwork connecting them called webs. The arrangement of the webs can vary significantly, giving the various types of truss bridges.

Worcester

This is notable as the rail runs over the top of the truss (so it is a deck truss bridge), rather than through the middle of it. I am not sure which variant is more common, but on models it is definitely the through version!



Lattice Girder Bridge

Also known as a lattice truss bridge in the US, they were popular from around 1848 to 1910 (to judge from the list on Wiki). This is a type of truss bridge, but here the webs form overlapping crosses.

Preston

This first example is an extension to an existing bridge with the WCML crosses the Ribble in Preston.


This image shows how the iron work continues beyond the pilaster.


Blackburn

The second example is just west of Blackburn station. It is also a bridge that has been extended - I am not sure side which was there first.


Croxley Green

This railway is now closed, but the bridge is still there. A better example, in my view, as the diagonals cross more.


From underneath.


Note that the two spans do not meet. This will be to allow for expansion.



Leeds

This is not a railway, this is where Whitehall Road crosses the River Aire.



Plate Girder Bridge

In a plate girder bridge, the top chord, bottom chord and web and combined into one single piece. They are very common across the whole country, and date from around 1890.


Preston

The ELR bridge over the Ribble is an impressive example.


It replaced an older structure in about 1930. I think the older bridge was an arched iron bridge.





Half Through Plate Girder Bridge

This version has the girder higher, to give more clearance underneath.

Leeds

So many bridges, they get their own page.

Entwistle

This road bridge is just south of the station.


And also.



Steel Girder Bridges

I am going to hold my hand up here and admit I a not certain of the difference between a steel bridge and a plate girder bridge, but I think plate girder bridges were built in sections that were bolted or riveted together, while steel girder bridges use single piece girders to span the gap. However, steel girders have similar webbing, so the difference can be hard to see. I think these examples, then, are steel girder bridges, but I am not certain!

Whalley

Just a little west of the village. The first image allows you to see the "I" girders that take the weight.



Where Fishergate crosses the railway, Preston; may well be a plate girder bridge.


This is in Manchester, just north of Prestwich station on the line to Bury.


These two were built by the Metropolitan Railway






Random notes

Iron and steel have a coefficient of expansion of between 10 and 12 mm per km per °C. A 100 m long bridge that changes from -10°C to +40°C will expand by 50 to 60 mm (brick and stone are comparable).

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