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Colne Valley Viaduct - Britain's longest railway bridge completed
 
Re: Colne Valley Viaduct - Britain's longest railway bridge completed
Posted by Mark A at 14:59, 11th September 2025
 
Asking Gemini the following (and then, separately, the length of the Leicester structure as it like the London and Greenwich was a mixture of brick arch runs and steel spans of various sorts and merged that response with this...)

How does the London and Greenwich Railway Viaduct compare in length to the Tay Bridge, the Forth Rail bridge and the new HS2 Colne Valley viaduct? Which is longest?

The new Colne Valley Viaduct on the HS2 line is now the longest railway bridge in the UK. With apologies for the tabbing, here's a comparison of the lengths:

Bridge                                                   Length
HS2 Colne Valley Viaduct                           3.4 km     (2.1 miles)
London and Greenwich Railway Viaduct   5.55 km   (3.45 miles)
Tay Bridge                                                   3.3 km     (2.04 miles)
Forth Rail Bridge                                   2.467 km (1.53 miles)
Great Central Leicester Viaduct                   2.4 km     (1.49 miles)

So... perhaps it's that the Colne Valley structure while eclipsed in length by certain other structures is made up of the longest clean series of spans.

Off topic: it can be instructive to take the lengths for some of the Forth Bridge's components and, in imagination, superimpose them on other locations. Those two spans clearing 521 metres, or even the warren trusses that connect the cantilevers - they'd clear 107 metres.

But then, closer to coffeeshop country, the spans of the rail bridge at Saltash, at 138 metres in length, and lifted to their final positions after being assembled ashore. Also, the prequel at Chepstow, with a 91 metre span and a possibly more benign construction site. I wish the Chepstow work had survived.

Mark

Re: Colne Valley Viaduct - Britain's longest railway bridge completed
Posted by matth1j at 14:19, 11th September 2025
 
My friend Gemini says:
The London and Greenwich Railway viaduct is not among Britain's longest railway bridges, but it is notable for a different reason: it is the longest run of brick railway arches in Britain.

The viaduct is a continuous structure that is 3.45 miles (5.55 km) long, consisting of 851 semi-circular arches and 27 bridges. It was the first steam railway to be built in the capital and one of the world's earliest elevated railway lines.

Re: Colne Valley Viaduct - Britain's longest railway bridge completed
Posted by Mark A at 14:09, 11th September 2025
 
The HS2 people have been fond of that figure, and not denigrating it, but doesn't the London and Greenwich Railway's viaduct from ~1836 have the better of it as far as length goes though?

Mark

Colne Valley Viaduct - Britain's longest railway bridge completed
Posted by matth1j at 13:47, 11th September 2025
 
...for HS2; 2.1 miles long. Looks impressive in the picture.
https://www.telegraph.co.uk/gift/bc071f750a7ec7f0

 
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