Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Discussion about street lighting, road signs, traffic signals - and all other street furniture - goes here.

Moderator: Site Management Team

Post Reply
User avatar
Tom Williams
Member
Posts: 78
Joined: Mon Jun 11, 2018 00:07
Location: Hereford, Herefordshire

Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Tom Williams » Mon Jul 15, 2019 21:04

Hi there,

Wasn't sure whether to put this here, but I was just wondering why all the railway bridges that I seem to see have these things in the way of the view of the track, like here:
https://www.google.com/maps/@52.0350103 ... K9Oxgw!2e0

User avatar
the cheesecake man
Member
Posts: 338
Joined: Mon Jan 07, 2019 13:21
Location: Sheffield

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by the cheesecake man » Mon Jul 15, 2019 21:28

I assume it's done to make it harder to jump in front of a train, throw things at it, or electrocute yourself on the wires.

User avatar
Chris Bertram
Member
Posts: 10651
Joined: Tue Nov 13, 2001 12:30
Location: Birmingham, England

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Chris Bertram » Mon Jul 15, 2019 21:48

I think it must be a legal requirement to have solid parapets on a bridge over a railway. Travelling westbound on M40 between J15 and J16, you see a long bridge carrying a road over both the motorway and the parallel railway line. For most of its length it has open railings, but over the railway line only, it has solid sides. I suspect that with light signals being so fundamental to railway safety, providing a shield against extraneous lights from motor traffic may have something to do with it.
“The quality of any advice anybody has to offer has to be judged against the quality of life they actually lead.” - Douglas Adams.

User avatar
Jonathan B4027
Member
Posts: 2153
Joined: Sun Jan 20, 2002 21:45
Location: Oxford or Birmingham

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Jonathan B4027 » Tue Jul 16, 2019 11:52

Also makes it a bit harder to drive through, ending up on the tracks. Train detection isn't going to know there is an obstruction.
Casino Manager: "It was a good night. Nothing Unusual."
Harold Shand: "Nothing unusual," he says! Eric's been blown to smithereens, Colin's been carved up, and I've got a bomb in me casino, and you say nothing unusual ?"

AndyB
SABRE Developer
Posts: 6621
Joined: Tue Dec 26, 2006 21:58
Location: Belfast N Ireland
Contact:

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by AndyB » Tue Jul 16, 2019 13:33

Don't forget that most road bridges over rail were built from stone, same as rivers. The M40 example (Shrewley Common) is definitely two separate bridges, and the Hereford example doesn't have enough room for containment armco (which, incidentally, is treated as adequate in a couple of places in NI!)

I know of a couple of bridges on the west side of Edinburgh where the sides have been raised quite considerably. I suspect that the reason is vandals throwing stones rather than additional protection against falling onto the overhead wires.

User avatar
rhyds
Elected Committee Member
Posts: 9913
Joined: Tue May 02, 2006 15:51
Location: Beautiful North Wales

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by rhyds » Tue Jul 16, 2019 14:00

Wasn't it one of the recommendations after the Selby rail crash?
Built for comfort, not speed.

User avatar
Johnathan404
Member
Posts: 11293
Joined: Tue Feb 01, 2005 16:54
Location: Dublin / Portsmouth
Contact:

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Johnathan404 » Tue Jul 16, 2019 14:25

This comes up surprisingly often, and only ever seems to attract speculation, despite us surely having members who have built the things!

Obviously the type of railing depends on the circumstance. Railways with overhead electric wires need to have higher barriers so you can't poke the wires with an umbrella. Bridges in areas with a history of anti-social behaviour may need barriers that are harder to climb or throw things over. Certain road layouts, traffic levels and bridge designs may warrant reinforcement, especially after Selby. Bridges where railways go over roads (not under) will need something to stop ballast being thrown over.

However, none of those points answer the OP's question as to why all bridges have some sort of filter over the railway section. I'm not sure it is any harder to climb than the usual grill, and if it's to reinforce the barrier it would need to be longer.

So this is going to be a guess as well, but it's the only answer I can see that makes sense and applies to all scenarios: it is to stop train drivers seeing a red taillight on the bridge and thinking it's an overhead signal.

This would be the same reason as to why roads that run parallel to railways often have some-kind of filter too.
I have websites about: motorway services | Fareham

User avatar
Chris Bertram
Member
Posts: 10651
Joined: Tue Nov 13, 2001 12:30
Location: Birmingham, England

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Chris Bertram » Tue Jul 16, 2019 14:38

AndyB wrote:
Tue Jul 16, 2019 13:33
Don't forget that most road bridges over rail were built from stone, same as rivers. The M40 example (Shrewley Common) is definitely two separate bridges, and the Hereford example doesn't have enough room for containment armco (which, incidentally, is treated as adequate in a couple of places in NI!)

I know of a couple of bridges on the west side of Edinburgh where the sides have been raised quite considerably. I suspect that the reason is vandals throwing stones rather than additional protection against falling onto the overhead wires.
The M40 bridge I'm thinking of is this one, near Turner's Green - this is a single bridge over both motorway and railway, and you can clearly see the solid section over the railway with open railings either side - the top of the solid section is at the same height as the remainder. The railway is not electrified - it's the Chiltern main line between Birmingham Snow Hill and Marylebone via Leamington, Banbury and Wycombe.
Last edited by Chris Bertram on Tue Jul 16, 2019 16:29, edited 1 time in total.
“The quality of any advice anybody has to offer has to be judged against the quality of life they actually lead.” - Douglas Adams.

User avatar
Brenley Corner
Member
Posts: 3641
Joined: Fri Apr 12, 2002 19:28
Location: nr. Canterbury, Kent

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Brenley Corner » Tue Jul 16, 2019 15:09

Would this also be to do in many cases with the protection of the railway from vehicles coming off the bridge (e.g, Great Heck) as well as the other suggestions already made. The M2 near J7 received an additional parapet on the hard shoulder over a railway bridge after this event, for example - Streetview.

Article of interest about this happening at Oxshott on the A244.

Tony
Brenley Corner: congesting traffic since 1963; discussing roads since 2002

User avatar
Viator
SABRE Wiki admin
Posts: 1753
Joined: Fri Mar 01, 2002 19:06
Location: Llan-giwg

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Viator » Tue Jul 16, 2019 15:20

Thinking of how old (probably still the majority of) railway bridges are, it probably also helped in avoiding frightening the horses.

User avatar
Big L
Member
Posts: 4093
Joined: Sun Nov 14, 2010 20:36
Location: B5012

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Big L » Tue Jul 16, 2019 18:26

This on the A10 is a good example of a long bridge with a short section with solid sides to go over the railway line. This one on the M23 is a little different.
Make poetry history.

User avatar
M4 Cardiff
Member
Posts: 1924
Joined: Mon Sep 20, 2004 15:12
Location: Leamington Spa

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by M4 Cardiff » Tue Jul 23, 2019 11:24

I think there is a law dating back from the Victorian times stating that all bridges (I think that station footbridges are exempt and had / have different design requirements) over railways must have solid parapets. Some very early bridges did have lattice parapets or fences, and there were accidents with items/livestock/vehicles ending up on the track. The law also stipulated minimum height requirements for the parapets, which is why these sections are often higher than the adjacent section. I think also that back in the days of steam, the use of solid parapets served to prevent steam burns to persons or livestock on the bridge at the time.

Where there are longer viaducts with the short 'solid' section, the 'solid' section is often just thin sheet metal attached to the existing barriers, but in the eyes of the law, that is required to make it 'solid', even though it does not add to the structural strength.

The post-Selby modifications generally comprised significant extensions to the 5T grade barriers upstream of railway underpasses.
Driving thrombosis caused this accident......a clot behind the wheel.

User avatar
nowster
Treasurer
Posts: 12669
Joined: Tue Aug 31, 2004 16:06
Location: Manchester

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by nowster » Tue Jul 23, 2019 11:39

How about this footbridge https://goo.gl/maps/KEuZz44CiGzpMtXP7 where half is over the road and half over the rails?

User avatar
Vierwielen
Member
Posts: 3547
Joined: Sun Jun 08, 2008 21:21
Location: Hampshire

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by Vierwielen » Tue Jul 23, 2019 15:08

High walls (whether or stone or steeel) also rmove the temptation of the driver being distracted by looking down the railway line. This is the same reason (I believe) that drivers of motor cars cannot look at the aeroplanes at Heathrow (See here). (Note, the comera on the Google Car are mounted on the car roof!).

drm567
Member
Posts: 566
Joined: Thu Jun 16, 2011 13:13
Location: Watford, Herts

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by drm567 » Tue Jul 23, 2019 16:48

Here's a pdf by Network Rail that explains the current rules. Start on page 30. http://www.bathnes.gov.uk/sites/default ... cation.pdf

And here are a couple of threads in another forum that deal with the historical reasons. As with all (?) forums there is a certain amount of ignorant speculation, but the first two answers in the solid parapet one are essentially on the ball.

https://www.railforums.co.uk/threads/wh ... id.118431/
https://www.railforums.co.uk/threads/br ... on.135720/

Edit - added the Network Rail pdf link

User avatar
the cheesecake man
Member
Posts: 338
Joined: Mon Jan 07, 2019 13:21
Location: Sheffield

Re: Why do road over rail bridges always seem to have these sides making it difficult to see the track?

Post by the cheesecake man » Tue Sep 17, 2019 13:23

It seems the same rules apply to tram over rail bridges.

Long viaduct taking the tram over various busy roads, with open fences, but just here it passes over a railway and has solid sides.

Post Reply