Roadway Under Bridge.

[The Johnster]

I believe the Cardiff location I mentioned may have started out in this way.  

[Philou]

@Ray Von

 

Don't forget to put the hogging and sagging curves as you had shown on your graph paper - it'll look all the better for it.

 

Here's a Google image of Lowther Road - the vertical sag and hog of the road can be seen plus the raised footway and, as mentioned by The Johnster, as a bonus the steps leading into the adjoining cul-de-sac are in the picture. As an aside, the bridge was originally a very wide plate girder affair which was demolished and replaced by a twin track concrete one. You can see the slope of the original abutments on the left hand side plus the concrete capping upon which the bearings would have rested - a bit of detail that is often left out.

 

LowtherRoad.pdf

 

Hope it's of use,

 

Cheers,

 

Philip

 

Edited February 23, 2019 by Philou

[Ray Von]

Cheers Philip, that does bear more than a passing resemblance to my set up (albeit that mine is a more compact version!)

 

The slope section is developing nicely, yesterday I smoothed down the polystyrene and applied several layers of Papier mache to further even out the larger lumps n bumps.

 

At this point the paper is still not completely dry!  I'm not sure if I will apply more mache, or move on to thin card and then the actual road surface (wet n dry paper most likely...)

 

 

[Philou]

Hello Ray Von,

 

I don't think you'll need more papier maché, it's only for your foundation. Mind when you're using thin card as when it's wet it will tend to buckle. I used exterior grade PVA painted over both sides which reduced its tendency to warp.

 

It's looking good - but you'll need to give your plate girder some support ;) .

 

Cheers,

 

Philip

 

 

[Ray Von]

Cheers, you don't think that the Bluetak will quite cut it then?!! 

 

When you say "support" do you mean something like abutments, sticking out further into the roadway or do you mean horizontal support, under the bridge itself?

 

I am pausing my plans since looking at the Lowther Rd images - I really like the idea of including a raised walkway, but that sends things off in a whole new direction!! 

 

Once the mache is completely dry and has contracted, I will be able to see if more layers are needed to hide any major imperfections - I'm hoping not!

 

Here is an image of the walkway:

 

 

[Philou]

Hi, yes, I know the road as it used to be on the circuit for taking the driving test - hill-start at either end! I don't know if you noticed from the Google aerial images, the raised footway nibbles quite away into the carriageway - a little more than the non-raised one.

 

Quite a few bridges in Cardiff have similar raised footways due to the near-sea level nature of the city and an inability to drain the 'sumps' in heavy rain.

 

Regarding the plate girder bridge support, it was said (in jest) as from the angle of the photo it looked as if the one end was hanging on by the magical qualities of fresh air. I think your comment regarding blu-tak explained that one .

 

On a slightly serious note though, the girders would normally rest on bearings at one end (the other end being fixed). The bearings will/would vary on the size and construction of the bridge (note: even concrete shrinks and expands under changes in temperature and requires a flexible bearing at one end), and the bearing might be a greased plate or a roller. Without suggesting that you re-model the bridge in any way, the end of the plate will need to be set a little way beyond your abutment with a little gap between the plate girder and the abutment, creating the space where the bearing would be normally. It gives an impression that bridge 'floats'.

 

Cheers,

 

Philip

[The Johnster]

The original Lowther Road bridge was a lot wider at one time, and carried 5 tracks.  From the foreground of the Google photo, headshunt for Crwys Road storage sidings with continued on to docks branch, down and up Rhymney Railway main, still extant, and the northern end of the Rhymney's Cranbrook Street Carriage Sidings, closed after the grouping.  These were built up a little from street level and the Rhymney's horse stables were beneath them, and I assume the remains still are although student accommodation has been built here in more recent years.  There was a square section stone chimney that survived here disused for many years which was part of a smithy on the premises.  

 

Before the First World War, the railways owned more horses than the armed forces, mostly used for local goods deliveries but also for shunting.  None of which is any use whatsoever to the OP, but may be of some interest to someone...

Edited February 24, 2019 by The Johnster

[Ray Von]

Hi, thanks Philip - that's really helpful.  Near me there are the remains of two girder bridges over roads - long since gone, I think this image offers the chance to get a good look at the structural support. 

 

 

Edited February 24, 2019 by Ray Von
Clashed with johnster there!

[Philou]

There you are - your photo shows quite clearly the four pads upon which would have rested the bearings of the four main girders (lined up under the rails of the tracks above). The pads in most cases would have been cast in concrete (sometimes dressed stone such as granite).

 

As an aside, if you think about it, the plates of your model bridge could be done away with. Oh? you might say. Well, look at some American railroad bridges - done on the cheap - two girders and the sleepers laid directly onto them. No sides or ballast - scary! I know which type of bridgework I prefer!

 

Cheers,

 

Philip

[Ray Von]

Cheers Philip, just shows how relatively "waffer thin" these supports are!  Your input is very much appreciated, Ray. 

 

 

[Nearholmer]

This one on Rochester/Chatham High Street might help too https://www.geograph.org.uk/photo/1043677

 

Notice the extra set of columns to ensure that the bridge span isn't too long.

 

I would certainly go for a narrower carriageway and raised pavements with railings, because I think both would add visual interest and stop it looking quite so unlikely.

[Philou]

@ Nearholmer

 

..... and on quite a skew too! It didn't look it face on. Nice bit of detailing if anyone wanted to have a bridge that is a little different. I agree regarding the raised footway though.

 

Cheers,

 

Philip

[Ray Von]

11 hours ago, Nearholmer said:

This one on Rochester/Chatham High Street might help too https://www.geograph.org.uk/photo/1043677

 

Notice the extra set of columns to ensure that the bridge span isn't too long.

 

I would certainly go for a narrower carriageway and raised pavements with railings, because I think both would add visual interest and stop it looking quite so unlikely.

 

That's a really interesting pic.  Is it an optical illusion, or is the bridge really rather close to the building with the blue window frames?? 

 

 

[Nearholmer]

It’s an intriguing place.

 

to the right, behind the buildings, a very steep hill rises up, and the buildings stand on what was once the forseshore of the Medway/Thames estuary. My brother lives not far along, behind where the photographer is standing, in an area called The Banks, which is all C18th and earlier buildings that were all originally associated with sea trade.

 

The forseshore was progressively moved outwards, to the left, and the railway was built on viaducts across reclaimed land, but it couldn’t run all the way on this land, because the huge naval dockyard was in the way, so at this point it had to turn inland. House were demolished to make a gap, so yes, it is practically in the bedrooms of the house with blue windows, then it pierced straight into the side of the hill, first in cutting, then in a tunnel.

 

There were sidings and yards at reclaimed land level, and when the SER wanted to get into the area, alongside the LC&DR that we see here, they built their Chatham terminus just round the back of the viaduct on the left ...... not really even in Chatham, because it was simply too expensive to go further.

 

The whole area would make a cracking model, because it had such a fantastic mix of buildings, although a fair few of the later Victorian ones have been cleared in the past 30-40 years.

 

a bit more including maps and another photo here https://spellerweb.net/rhindex/UKRH/SECR/Extension.html

 

 

 

Edited February 25, 2019 by Nearholmer

[Philou]

@ Ray Von

 

I don't know if when you clicked on Nearholmer's link (post No 3477465), you were able to view the pane on the right hand side that had other photos showing further shots of the bridge - though it didn't show exactly how close was close!

 

Cheers,

 

Philip

 

Edited to add that regarding the proximity of the bridge to buildings, it was always a surprise to me when travelling on the southern side of London that on the raised sections (on viaduct) just how close the tracks run to the buildings - Brixton springs to mind.

Edited February 25, 2019 by Philou

[Nearholmer]

Southwark Cathedral, and the ‘rookeries’ that used to exist until recently just on the Charing Cross side, are another great example.

 

and, here is the other side that f the Rochester/Chatham bridge https://www.geograph.org.uk/photo/4395160

Edited February 25, 2019 by Nearholmer

[Ray Von]

Blimey! :

 

 

 

 

[Nearholmer]

Next time I’m down that way, i’ll Look more closely at that building, because I’m beginning to think it might be an insertion or a replacement - hard to be sure in a google photo, but the brickwork look “all stretchers”, which implies modern construction.

[Ray Von]

I think you may be right, if not the whole building then maybe just the façade?  

[Nearholmer]

Looking at old maps, there seem to have been two smaller buildings on that plot, one equally close to the railway.

[Ray Von]

The Papier mache finally dried, have now applied a thin card base layer, fixed with PVA glue.  There are still a few gaps apparent, I'm thinking of making a paper-pulp and glue concoction to fill them in.

 

In the meantime, I have had to masking-tape the card to the slope to hold it in situ.  Unfortunately, the tape doesn't hold to the polystyrene which the body of the ramp is made of!  I have enlisted cocktail sticks to hold the tape in place.

 

Contender for one of the more strange images posted:

 

 

[JDW]

It's certainly a strong contender for that award!  See, me, I'm much less creative, I'd have just wrapped the masking tape all the way around...

[Ray Von]

It was the end of the roll, which is probably why it wasn't sticking very well!  Anyway, the sticks have been removed now as the glue has dried nicely. 

[shiny]

On 20/02/2019 at 17:30, DaveF said:

I don't know if these photos help at all.

 

 

Wolverhampton 86260 down pass crossing Lock Street bridge April 77 J5693.jpg

A lack of clearance here so it has bollards to close it off.

 

David

 

Perfect - I've been looking for a picture of exactly that sort of thing.

Many thanks!

 

 

[Ray Von]

Update:

 

Progress has been slow what with one thing and another, but during a drawer-rummage I found something that I must've previously thought useful, and put away for a rainy day:

The front cover of an A4 clear plastic organiser thing!  The inner pages having long since deteriorated, the flexible but sturdy cover has proved an ideal material  for the second-to-last layer of the slope.

 

I wasn't happy with how the thin card layer looked once the glue had well and truly dried, and considered removing it.  However, having found this semi-rigid plastic sheet, the card has proved more than suitable as a supporting layer.  I have left the plastic long and overhanging at either end to add smoothness to the approach, this works especially well at the top I think.

 

There are a lot of gaps to fill, and I am thinking carefully about how to plug them, options I've come up with so far are, Papier mache, polystyrene pieces, scrap cork, all of which involve PVA glue...

 

Here are images of the slope as it is now, you might spot that the knife got away at one point and spoilt the edge!