Building a r1 curved bridge from upvc angle

[a98087]

One of my current projects is a small railway extension, I’ve decided to add a small r1 loop on, as part of some storage sidings,

For a challenge I’ve decided to make a curved bridge out of upvc angle

It’s based loosely on the one from Barnstable that crossed the river

Here’s some pictures of what I’ve
Done so far

Overall view showing the track layout, the track is currently on some fibreglass panels cut to a rough size, that I might reuse


Another view, showing the loop, storage sidings, reversing triangle and site of 2 large rockeries/mountains to make it look pretty

This is my first test piece, I’ve cut the 40mm by 40mm angle into 3 strips
2 x 1.5m lengths -for bridge
1x 2m length for reinforcing and testing how techniques

These next to photos show the curves possible when you make cuts and 2cm intervals and then remove alternate sections

I’ve only done a 10cm length as a short test but it looks promising!

Dan

 

[Rhinochugger]

One of my current projects is a small railway extension, I’ve decided to add a small r1 loop on, as part of some storage sidings,

For a challenge I’ve decided to make a curved bridge out of upvc angle

It’s based loosely on the one from Barnstable that crossed the river

Here’s some pictures of what I’ve
Done so far

Overall view showing the track layout, the track is currently on some fibreglass panels cut to a rough size, that I might reuse

View attachment 238272
Another view, showing the loop, storage sidings, reversing triangle and site of 2 large rockeries/mountains to make it look pretty
View attachment 238275
This is my first test piece, I’ve cut the 40mm by 40mm angle into 3 strips
2 x 1.5m lengths -for bridge
1x 2m length for reinforcing and testing how techniques

These next to photos show the curves possible when you make cuts and 2cm intervals and then remove alternate sections

I’ve only done a 10cm length as a short test but it looks promising!

Dan
View attachment 238273 View attachment 238274

Curved bridges are less common, the main issue being the additional number of supports required and the comparatively short spans - it's all to do with the overturning moment at the outer edge of the curve

 

[a98087]

Thanks for the advice about curved bridges, I shall bare that in mind when I build the legs.

I had a little test, and built a short section to prove the concept works and start working out dimensions.

Here’s the pictures as they show lots of details

1st pic
The wood and rails form the structural deck





Top view
The eventual plan is to use some solid material to make a deck or slats to keep the sides and track in place
Some care is needed to get a constant even curve.
I plan to make a jig, the correct width of the bridge with slots in the rails to ensure consistency



Proportions look good with a wagon, the pencil is there to stop the wagon rolling away


The idea has good potential, just needs a fine tuning,

Does anybody else know how wide to make it? I’m fairly sure I’ve made it to narrow

Dan

 

[Eaglecliff]

Put your longest, widest loco or coach on a couple of lengths of R1 on a big piece of any old paper, run vehicle round curve with upright pencil held against widest bit, repeat with pencil on opposite side, distance between pencil lines is your answer, plus a bit to be on the safe side.

 

[Riograndad]

Exactly what Eagle says.It will depend on the locos and rolling stock you have or plan to get,if all fits the bridge that you have then should be fine but if you plan to get lets assume 4 axle bogie stock then inner and outer overhangs will be a problem,in my case I will have to move a siding to accommodate the overhang on the front my Connie as when coming off R3 curve onto straight it hits the cars on the siding,until now no problems even with the Sumpter mallet,good luck with you buildAn alternative would be to build without sides such as a trestle which has no side clearance issues?

 

[GAP]

Exactly what Eagle says.It will depend on the locos and rolling stock you have or plan to get,if all fits the bridge that you have then should be fine but if you plan to get lets assume 4 axle bogie stock then inner and outer overhangs will be a problem,in my case I will have to move a siding to accommodate the overhang on the front my Connie as when coming off R3 curve onto straight it hits the cars on the siding,until now no problems even with the Sumpter mallet,good luck with you buildAn alternative would be to build without sides such as a trestle which has no side clearance issues?

Attached are photos of my curved trestle bridges I had no clearance issue with them even when I ran my 1:20.3 Connie over them, one was just a lot shorter but I used the same jig for the bents on both.
They were made out of hardwood garden stakes but are now unfortunately ash in the fire place as the railway has been pulled up for transportation to a new home.

 

[dunnyrail]

A couple of pics of my curved ally viaduct, you can get some idea of the width I have allowed from the pics and I am using R3 curves. Remember that on the real thing there would be a walkway (mine is still in roundtoit stage) for staff to get across safely even while a train is passing over the viaduct.

 

[Nodrog1826]

I made my R3 one out of reclaimed conservatory roofing that had collapsed, (Not mine I hasten to add, never had one.) and ridge tiles.



How I made it up...

https://www.gscalecentral.net/threads/eighton-bahn-upvc-and-ridge-tile-bridge.257807/#post-257810

...because it was made up as I went along

 

[Gavin Sowry]

12mm x 12mm hardwood garden stakes, just like GAP used. R1 (of course, it is Taita Gorge, after all).
Couple of hours work. Cost, about 3 quid all up in the Queen's coin.

 

[GAP]

View attachment 238663

12mm x 12mm hardwood garden stakes, just like GAP used. R1 (of course, it is Taita Gorge, after all).
Couple of hours work. Cost, about 3 quid all up in the Queen's coin.

Did you embed them in concrete or just dig them into the ground?
Mine were just dug into the ground and when I pulled them up a couple had rotted of at ground level (after about 6 years), gregh had the same problem at the sandstone & termite.
I did make a small one out of plastic trim and that is still OK after 9 years

 

[Gavin Sowry]

Did you embed them in concrete or just dig them into the ground?
Mine were just dug into the ground and when I pulled them up a couple had rotted of at ground level (after about 6 years), gregh had the same problem at the sandstone & termite.
I did make a small one out of plastic trim and that is still OK after 9 years

Buried it prototypically in the dirt.

Check out my Taita Gorge Railway thread for the saga of this bridge.

 

[dunnyrail]

Did you embed them in concrete or just dig them into the ground?
Mine were just dug into the ground and when I pulled them up a couple had rotted of at ground level (after about 6 years), gregh had the same problem at the sandstone & termite.
I did make a small one out of plastic trim and that is still OK after 9 years

Wood burried in either concrete or ground will not last for ever. This is why so many fences fall down at the slightest storm. If possible better to have say a short section of metal below the post that can be burried then the posts terminating in good self draininf stones a bit like in Gav's picture.

 

[GAP]

Wood burried in either concrete or ground will not last for ever. This is why so many fences fall down at the slightest storm. If possible better to have say a short section of metal below the post that can be burried then the posts terminating in good self draininf stones a bit like in Gav's picture.

My next layout is going to be raised on either on metal posts or concrete blocks due it being in a high termite area, even treated timber does not last.
Just had a treated fence post totally eaten away but pest guy said there was a dodgy batch in town but I won't be risking it.
No ground to timber contact what so ever.

 

[dunnyrail]

My next layout is going to be raised on either on metal posts or concrete blocks due it being in a high termite area, even treated timber does not last.
Just had a treated fence post totally eaten away but pest guy said there was a dodgy batch in town but I won't be risking it.
No ground to timber contact what so ever.

Lucky in the UK that we have few problems with Termites. Though I do gather there are small Colonies in I think either Devon or Cornwall.

 

[a98087]

Thanks for all the advice and pictures, when I started the bridge the spec was simple, curved, uk style (not a trestle) and weatherproof.

I intend to use plastic for the legs to prevent any detoriation

Dan

 

[GAP]

Thanks for all the advice and pictures, when I started the bridge the spec was simple, curved, uk style (not a trestle) and weatherproof.

I intend to use plastic for the legs to prevent any detoriation

Dan

How about something like the curved viaduct on this page?
http://www.members.optusnet.com.au/satr/hebel.htm
Very UK and will be around for years to come.
I've seen it up close and will try to include something in my new layout let the termites/white ants eat that and play fair.

 

[spoz]

Wood burried in either concrete or ground will not last for ever. This is why so many fences fall down at the slightest storm. If possible better to have say a short section of metal below the post that can be burried then the posts terminating in good self draininf stones a bit like in Gav's picture.

I've just torn down a section of the railway I constructed early on but that became redundant when I completed the main line. It was on 75x45mm H3 posts set in concrete underground, the soil is clay and they had been there for a bit over 10 years. There was some wastage, maybe 5% for perhaps 25mm around the point of interface between the part in the concrete and the part just in dirt, presumably because moisture was accumulating there; otherwise they were in excellent condition and are mostly being reused in a new section I'm currently building. I'm pretty happy with that; if they last another 10-15 years that will probably just about see me out, and the son-in-law and grandsons can decide what to do next! I do live in Adelaide though which has a relatively dry climate

 

[Gavin Sowry]

I've just torn down a section of the railway I constructed early on but that became redundant when I completed the main line. It was on 75x45mm H3 posts set in concrete underground, the soil is clay and they had been there for a bit over 10 years. There was some wastage, maybe 5% for perhaps 25mm around the point of interface between the part in the concrete and the part just in dirt, presumably because moisture was accumulating there; otherwise they were in excellent condition and are mostly being reused in a new section I'm currently building. I'm pretty happy with that; if they last another 10-15 years that will probably just about see me out, and the son-in-law and grandsons can decide what to do next! I do live in Adelaide though which has a relatively dry climate

Timber will rot when both moisture, and oxygen, are present.

A timber post out of the ground dries out often enough to virtually eliminate rotting. A post well and truly underground, will be starved of oxygen. At the interface, there is oxygen, and more often than not, moisture. Hence the place where it is most likely to rot.

 

[stockers]

and concrete is the killer. Posts in dirt will last a lot longer. I was talking with my neighbour the other evening, he is a fencing contractor. He suggests using dry mix concrete, suitably rammed down, to leave an open texture to the finished result so that water can drain through.

 

[Rhinochugger]

and concrete is the killer. Posts in dirt will last a lot longer. I was talking with my neighbour the other evening, he is a fencing contractor. He suggests using dry mix concrete, suitably rammed down, to leave an open texture to the finished result so that water can drain through.

Timber posts will last longer in clay soils than sandy soils - because there is less air, and the microbes that cause timber to rot need air to breathe