Large Scale Central

Curved, multiple-arch concrete bridge

Track and Trestles
#1

One section of track which will cross the west canyon on my layout comes close to the upper level pathway and could get bumped from time to time. So I want a bridge that will be extremely solid and sturdy. I decided on a cast, reinforced concrete bridge with four arches. About half of it is curved, with a slight curve in the opposite direction at the other end. Total length is four and a half feet.

I considered casting the bridge in place, just like the “real thing”, but quickly decided that would be much more trouble than it’s worth.

I’ve spent the past several days building the wooden form. Didn’t have any directions to go by, just followed what seemed a logical method. Tomorrow’s the big day – pouring the concrete into the form! A rough calculation indicates I’ll need about 1.75 cubic feet of cement. I plan to use a 50/50 mix of high-strength mortar and vinyl patching cement.

So, we’ll soon see whether it turns out as planned!

#2

Last person I knew who poured something in concrete with the idea he’d move it into place discovered after it was poured he would need a crane to move it…:frowning:

#3

Heh! I don’t think it will come to that. I may need to press one of the neighbors into service though.

#4

Concrete weights about 150# a cubic foot.

#5

I would think seriously to cast it in-place. This thing could end up easily weighing over 400 lbs. Thats a heckova thing to try moving by hand.

#6

For those that know him, I’m still chuckling over (big black hat) JJ’s cast tunnel fiasco…:lol:

#7

I’m getting ready to build a curved trestle and even that will be built in place. Concrete? Makes my back hurt!

#8
Warren Mumpower said:
For those that know him, I'm still chuckling over (big black hat) JJ's cast tunnel fiasco..
Do tell...
#9

Has anyone ever tried making a concrete bridge with Jig Stones? Doesn’t look much harder than a wood trestle on the website. www.jigstones.com

Mark Selep

#10

Guys,

there is a section of Jack Verducci’s new book “How to Design and Build Your Garden Railroad” that deals with a couple of different ways to build Viaducts, Stone Bridges, and Concrete Arch Bridges…

it may lend a hand if you are interested in a pretty good book for us beginners…I bought my copy from Amazon and saved a good deal of Cash!

Awaiting some photos of all this cool work you guys are planning/doing! I’m currently stalled out right now :frowning:

cale

#11
Bob McCown said:
Warren Mumpower said:
For those that know him, I'm still chuckling over (big black hat) JJ's cast tunnel fiasco..
Do tell...
Bob, heres the story... http://www.mylargescale.com/forum/topic.asp?TOPIC_ID=40401&SearchTerms=concrete,tunnel

John J (JJ) in Az cast a concrete tunnel, then couldnt move it. Suggested reading for Ray.

Heres how it ended…

http://www.mylargescale.com/forum/topic.asp?TOPIC_ID=41217&SearchTerms=concrete,tunnel

And Warren right, I still get a chuckle out of it too.

#12

Well, the pour went well today. I did have a couple corner joints that weren’t as tight as they should have been, resulting in a bit of leakage and some corners that aren’t as sharp as I’d like, but still acceptable. I was able to remove the form this evening. Found I’d poured too much cement into the three longest piers of the bridge, and had to chisel them down until they were a few inches shorter.

It looks like the weight is within reason and should not be a problem for two persons to carry. However, I probably won’t try to move it for a day or two so that it will have time to fully cure. Besides, I still have to dig out the holes for the bridge piers to be anchored into.

I’ll post pics as soon as I get them.

#13

Ray, I know this maybe a little late, I had trouble accessing my freight shed to up load photos. I also had a location that required a low level concrete bridge to allow storm water to escape under double tracks. Although my bridge may be somewhat lower than yours, the construction methods are the same.

Formwork in place, ready for concrete pouring.

Grey plastic is electricial tape, smooths concrete finish and makes it easer to remove formwork.

Formwork removed.

This the view from ground level.

Once the new concret bridge is cured, small concrete blocks are glued to the arch sides, simillar to this small culvert. Regards Wayne

#14

Yesterday I got one of the neighbors to help me move the bridge. Lifting it wasn’t too bad, I’d guess it weighs around 250-300 pounds. Getting it up onto the hill was a bit of a problem though – it had to go over a “step” of nearly two feet, too high to simply walk over with that much load. As we lifted it onto the raised area it got tweaked and cracked. Fortunately not too serious, nothing that can’t be repaired.

Eventually we got it into rough position and later I manipulated it into more precise location. This week I’d like to cement it into place and begin building up the rock canyon around it. Don’t know how much time I’ll have to work on it though, as my wife is having some health problems.

#15

Hope she feels better Ray, post a couple pics when you get the chance.

#16

Cris’ health situation seems to be improving, though she’s not out of the woods yet. Yesterday I did manage to get most of the rocks cemented in around the bridge, and it looks great. Didn’t have much time to work on it today but tomorrow morning should be free. I have lots to do, including running conduit up the canyon, putting in the rocks for the rest of the canyon, digging out the lower end of the canyon, building stone steps for the pathway that goes behind the bridge, and creating a section of concrete path with a channel for the track to fit into where it crosses the path.

On the upper level behind the bridge and path, I also need to finalize the track positions, add rocks to the gullies, and build several scale retaining walls.

#17

I’ve uploaded five new photos, beginning with this one:

http://albums.photo.epson.com/j/ViewPhoto?u=3009006&a=32116967&p=75535215

The first photo shows the completed center section of the mountains at the rear of the layout. Note the veins of different colored rock.

The second photo shows the wooden form I built to make my concrete bridge. It was built upside down, and the concrete was poured into the “legs” of the bridge. The form was held together with sheetmetal screws and a few clamps.

The third photo shows the bridge after the form was removed.

The fourth photo shows the bridge after it was placed into position on the layout, but before it was fully cemented in place. The bridge was designed so that there would be a shallow channel in the top of the bridge, into which the track would be laid. This channel is wide enough to allow some shifting of the track due to heat expansion, and also provides some leeway in positioning the bridge.

The last photo shows the bridge after some of the rocks were cemented in around it. There will be a stone pathway directly behind the bridge. The path has not yet been finished. The rest of the canyon is also unfinished in this photo.

To the left of the concrete bridge there will eventually be a through truss bridge. A wooden plank fills in as a temporary bridge until the truss bridge can be built.

#18

Ray cool looking bridge. Great looking layout also. Did not envey you having to carry in place. Ouch Later RJD

#19

Another milestone: With the concrete bridge installed, I now have one section of track that runs all the way from the east end to the west end.

#20

Cool bridge.