Passenger Footbridge - average height

[Andy873]

How high would an average Victorian railway passenger footbridge be? here I'm talking about a typical L&Y iron footbridge that simply connected two platforms at a railway station. The footbridge in question is just beyond the ends of the platforms if that helps.

I'm curious to know as a workman painting it fell off and hit the ground circa 1900.

Thanks,
Andy.

 

[zwk500]

Not much taller than that railway's loading gauge, I suspect. According to this website: https://www.devboats.co.uk/gwdrawings/loadinggauges.php, the L&Y had a centreline height of 13'6, among the larger of companies.

The lowest bridge girder would presumably have been about 14' from the top of rail level, with the walkway slightly above that and then you would also need to know where the ground/platform level was in relation to top of rail to know how far the fall was. 3-4m maybe?

 

[Andy873]

The lowest bridge girder would presumably have been about 14' from the top of rail level, with the walkway slightly above that and then you would also need to know where the ground/platform level was in relation to top of rail to know how far the fall was. 3-4m maybe?

Thanks for that, often wondered just how high those bridges were.

 

[david_g]

According to "The Permanent Way in Miniature - Prototype Considerations" by Derek Genzel which is on the Scalefour Society website the "desirable" clearance from railhead to overline structure was 15'0". Derek was a member of the Permanent Way Institute so presumably knows his stuff, the document has a lot of information on clearances, track/structure/formation dimensions with lots of drawings but is in the "members only" area so posting a link won't help.

 

[Mcr Warrior]

If 15 foot was the clearance on non-electrified lines, what minimum height clearance is typically required, these days, where overhead (25kVAC) electric wires are in use?

 

[zwk500]

If 15 foot was the clearance on non-electrified lines, what minimum height clearance is typically required, these days, where overhead (25kVAC) electric wires are in use?

According to this document: https://www.bathnes.gov.uk/sites/de...ng/nr_a_guide_to_overhead_electrification.pdf

(15' = 4.572m)
5.1m for OLE without any further considerations.
4.78m for OLE with fixtures directly on the overline structure (this reduces the movement of wires through the bridge
4.5m acceptable with specific maintenance regimes.

 

[Andy873]

According to "The Permanent Way in Miniature - Prototype Considerations" by Derek Genzel which is on the Scalefour Society website the "desirable" clearance from railhead to overline structure was 15'0". Derek was a member of the Permanent Way Institute so presumably knows his stuff

I'm sure you're right about Derek. It matches up with what I've been told - the man fell approximately 17 feet to ground level. Thanks for that.

 

[AM9]

Not much taller than that railway's loading gauge, I suspect. According to this website: https://www.devboats.co.uk/gwdrawings/loadinggauges.php, the L&Y had a centreline height of 13'6, among the larger of companies.

The lowest bridge girder would presumably have been about 14' from the top of rail level, with the walkway slightly above that and then you would also need to know where the ground/platform level was in relation to top of rail to know how far the fall was. 3-4m maybe?

Wouldn't there have been a few extra inches that allowed for the smoke deflectors in 1900? Their removal when lines eradicated steam in the '60s gave a bit more clearance for OLE.

 

[Snow1964]

Wouldn't there have been a few extra inches that allowed for the smoke deflectors in 1900? Their removal when lines eradicated steam in the '60s gave a bit more clearance for OLE.

And back before 1900 were still some some carriages with lighting canisters on roof (the lights used before gas lighting and electric lights), although roofs were lower. Wouldn't think of things on roof nowadays that might have been there in 1800s when bridge was built

 

[Mcr Warrior]

According to this document: https://www.bathnes.gov.uk/sites/de...ng/nr_a_guide_to_overhead_electrification.pdf

(15' = 4.572m)
5.1m for OLE without any further considerations.
4.78m for OLE with fixtures directly on the overline structure (this reduces the movement of wires through the bridge
4.5m acceptable with specific maintenance regimes.

Does this explain why, in certain circumstances, trackbeds are sometimes lowered to allow some form of OHLE to subsequently be installed, if the height of the structure above (overbridge, tunnel roof, etc.) cannot easily be raised?

 

[AM9]

Does this explain why, in certain circumstances, trackbeds are sometimes lowered to allow some form of OHLE to subsequently be installed, if the height of the structure above (overbridge, tunnel roof, etc.) cannot easily be raised?

I don't think that track lowering is a trivial act, so inadequate clearance under a footbridge is more likely to be fixed by raising, removing or replacing the footbridge, especially if the footbridge is the only non-accessible way of crossing the tracks.

 

[Mcr Warrior]

I don't think that track lowering is a trivial act...

Me neither, to be fair, likely to be equally if not more costly / technically difficult, which is why I made reference to "certain circumstances".

 

[zwk500]

Does this explain why, in certain circumstances, trackbeds are sometimes lowered to allow some form of OHLE to subsequently be installed, if the height of the structure above (overbridge, tunnel roof, etc.) cannot easily be raised?

It is one reason yes - another reason for lowering track is to get greater gauge clearance on the 'shoulders' although as @AM9 says, it's not a trivial thing to do (there is a video on YouTube of some track lowering near Bathampton jn I think).