Why are railway bridge parapets solid?

[BanburyBlue]

Hi, I've been wondering for a while why when road bridges cross railway lines the parapets are normally brick or concrete, whereas when roads cross other roads, rivers etc the parapets are often see through. I know there are exceptions (M40 crossing Chiltern line just south of J10) but normally this seems to be the case?

Any reason?

 

[Railsigns]

Hi, I've been wondering for a while why when road bridges cross railway lines the parapets are normally brick or concrete, whereas when roads cross other roads, rivers etc the parapets are often see through. I know there are exceptions (M40 crossing Chiltern line just south of J10) but normally this seems to be the case?

Any reason?

It's because many railways have 25 kV wires above them, so you don't want to be dangling legs or other things through the spaces in a non-solid parapet.

 

[AM9]

Hi, I've been wondering for a while why when road bridges cross railway lines the parapets are normally brick or concrete, whereas when roads cross other roads, rivers etc the parapets are often see through. I know there are exceptions (M40 crossing Chiltern line just south of J10) but normally this seems to be the case?

Any reason?

I think that there's two issues here:
1) Railway companies who built road overbridges originally wanted the railway to be protected from objects falling from carts etc. that passed over the bridges in the 19th century. In addition bridges of that era frequently relied on the structure above the roadway for their strength
2) Railway tracks are essentially unattended in terms of public access and trains travel assuming that. Roads however are used continuously by traffic that in the event of an obstruction falling from the bridge, (or threatening to jump) can usually stop, and certainly report an issue to the authorities. It is less so on high speed roads, e.g. motoways, where there is a general discouragement of stopping, hence the trend to make bridge parapets more effective in keeping pedestrians where they belong.

 

[BanburyBlue]

It's because many railways have 25 kV wires above them, so you don't want to be dangling legs or other things through the spaces in a non-solid parapet.

Thank you Railsigns. BTW, what is a Datum Plate? Another question I've been meaning to ask for ages?

 

[Railsigns]

BTW, what is a Datum Plate? Another question I've been meaning to ask for ages?

I have an explanation here.

 

[snowball]

It's because many railways have 25 kV wires above them, so you don't want to be dangling legs or other things through the spaces in a non-solid parapet.

I think it's a legal requirement dating from before 25kV electrification.

 

[Railsigns]

I think it's a legal requirement dating from before 25kV electrification.

The Ministry of Transport 'requirements' of 1950 merely stated: "Road overbridges should preferably have closed parapets with no foothold on the inner face."

Road over rail bridges certainly do exist with open parapets, for example: http://www.geograph.org.uk/photo/4241377

 

[broadgage]

For the reasons already given, most bridges over railways have closed parapets, but this is clearly not an absolute requirement.
There is one over the West Somerset Railway at Watchet station. Although that is a preserved railway, the bridge was the same in BR days.

 

[snowball]

Road over rail bridges built in the last 50 or more years have either a solid parapet, or an open parapet supplemented by a fine grid of thick wire. Often on a long road viaduct, a section which is above a railway will have the wire grid when the rest of the viaduct doesn't.

 

[Tio Terry]

Currently, the Technical Standards for Interoperability, Infrastructure and Energy, call for a 1.8M high parapet to prevent any chance of someone accessing any part of the OHEL from the bridge easily, it would have to be a deliberate act.

There are, of course, many structures which do not comply with this but any new, or modified, ones must do so for TEN's routes at least, the ORR adopts the view that all new build or significantly modified structures will also.

 

[najaB]

BTW, what is a Datum Plate? Another question I've been meaning to ask for ages?

Wow, through the looking-glass we go!

To BanburyBlue your post made me laugh as there's a long history of people posting photos of datum plates asking "What's this thing?" Hence Railsigns avatar.

 

[BanburyBlue]

Wow, through the looking-glass we go!

To BanburyBlue your post made me laugh as there's a long history of people posting photos of datum plates asking "What's this thing?" Hence Railsigns avatar.

Glad to know my post had some use

 

[edwin_m]

Before the invention of modern crash barriers most bridges of roads over anything would have had solid parapets, which would have had a good chance of stopping a horse and cart going over the edge. This would have included almost all road-over-rail bridges of the Victorian era.

Crash barriers allowed open-parapet road bridges to be as good or better at restraining motor vehicles. But as noted above a modern road-over-rail bridge will always have a solid parapet even if the railway isn't electrified (easier to build it now than maybe add it later) and even if the solid parapet is merely an open parapet with a steel plate added.

 

[61653 HTAFC]

I'd often wondered if it was to prevent road accidents caused by enthusiasts looking at the railway instead of the road...!

 

[Western Lord]

I'd often wondered if it was to prevent road accidents caused by enthusiasts looking at the railway instead of the road...!

Like the solid panels attached to the perimeter fence at Heathrow!

 

[AM9]

I'd often wondered if it was to prevent road accidents caused by enthusiasts looking at the railway instead of the road...!

But that would equally apply to a bridge with anything that road vehicle drivers might find distracting.

 

[theageofthetra]

I would have thought another reason would have been Victorians not wishing for train crew to catch sight of the forbidden fruits of a ladies ankles (or, heaven forbid, a bit of leg)! Come to think of it how many station footbridges could allow such a view from the footplate?

 

[61653 HTAFC]

I would have thought another reason would have been Victorians not wishing for train crew to catch sight of the forbidden fruits of a ladies ankles (or, heaven forbid, a bit of leg)! Come to think of it how many station footbridges could allow such a view from the footplate?

Ravensthorpe could, though the population round there are likely to be dressed from head-to-toe in black...