Curved steel bridges--they exist

Regarding the questions posed about curved bridge spans here recently:
when I read this, I knew there was an article on this in one of my model
RR mags. I finally found it in the August, 1994 issue of /Mainline
Modeler/,
a very interesting 6-page article devoted to this subject.
I've uploaded a couple of scans to links given below. To the poster who
said that such a thing wasn't possible ("They would tumble to
the earth when the first train passed over them"), here's living proof
that it is.
These are all in West Virginia (C&O, B&O, Virginian).
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Reply to
David Nebenzahl
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DN> Regarding the questions posed about curved bridge spans here recently: DN> when I read this, I knew there was an article on this in one of my model DN> RR mags. I finally found it in the August, 1994 issue of /Mainline DN> Modeler/, a very interesting 6-page article devoted to this subject. DN> DN> I've uploaded a couple of scans to links given below. To the poster who DN> said that such a thing wasn't possible ("They would tumble to DN> the earth when the first train passed over them"), here's living proof DN> that it is. DN> DN> These are all in West Virginia (C&O, B&O, Virginian). DN> DN>
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It would be nice if you posted these images to someplace where they would in fact be available. I'm getting *bandwidth exceded messages*. You need increase your bandwidth or upload them to a site where you have more bandwidth available.
I was going to look to see if the actual spans were curved. It is correct that there are many cases of a curve on a trestle or bridge, but usually the *individual* spans are in fact straight (track curves, but the girders are all straight). Given that you named the images 'CurvedTrestle1.jpg' and 'CurvedTrestle2.jpg' suggests that these are trestles. Often trestles use short spans and it is easy enough to make each successive span at a small angle to the previous span and then lay a curved section of track on top. I don't know if that is the case here, because I cannot see the images!
DN> DN> DN> -- DN> Pierre, mon ami. Jetez encore un Scientologiste DN> dans le baquet d'acide. DN> DN> - from a posting in alt.religion.scientology titled DN> "France recommends dissolving Scientologists" DN>
Robert Heller -- 978-544-6933 Deepwoods Software -- Linux Installation and Administration
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Reply to
Robert Heller
In the latter photo, short, straight sections of plate girder with small incidental angles is what was engineered. In the first photo, it's harder to tell, since that is a longer span, a deck bridge and the foreshortening makes it a tough call.
Reply to
RWM
RH> David Nebenzahl , RH> RH> RH> DN> Regarding the questions posed about curved bridge spans here recently: RH> DN> when I read this, I knew there was an article on this in one of my model RH> DN> RR mags. I finally found it in the August, 1994 issue of /Mainline RH> DN> Modeler/, a very interesting 6-page article devoted to this subject. RH> DN> RH> DN> I've uploaded a couple of scans to links given below. To the poster who RH> DN> said that such a thing wasn't possible ("They would tumble to RH> DN> the earth when the first train passed over them"), here's living proof RH> DN> that it is. RH> DN> RH> DN> These are all in West Virginia (C&O, B&O, Virginian). RH> DN> RH> DN>
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DN>
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RH> It would be nice if you posted these images to someplace where they RH> would in fact be available. I'm getting *bandwidth exceded messages*. RH> You need increase your bandwidth or upload them to a site where you have RH> more bandwidth available. RH> RH> I was going to look to see if the actual spans were curved. It is RH> correct that there are many cases of a curve on a trestle or bridge, but RH> usually the *individual* spans are in fact straight (track curves, but RH> the girders are all straight). Given that you named the images RH> 'CurvedTrestle1.jpg' and 'CurvedTrestle2.jpg' suggests that these are RH> trestles. Often trestles use short spans and it is easy enough to make RH> each successive span at a small angle to the previous span and then lay RH> a curved section of track on top. I don't know if that is the case RH> here, because I cannot see the images!
The images are showing up now. Yes, it is as I stated above: the girder spans are in fact straight sections (and wider than normal), with curved track laid on top. Each of the *spans* is straight, even though there is curved trackage. Things are a bit more obvious with the through plate bridges -- it is harder to tell with the deck bridge.
RH> RH> DN> RH> DN> RH> DN> -- RH> DN> Pierre, mon ami. Jetez encore un Scientologiste RH> DN> dans le baquet d'acide. RH> DN> RH> DN> - from a posting in alt.religion.scientology titled RH> DN> "France recommends dissolving Scientologists" RH> DN> RH> RH> Robert Heller -- 978-544-6933 RH> Deepwoods Software -- Linux Installation and Administration RH>
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-- Web Hosting, with CGI and Database RH> snipped-for-privacy@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk RH> RH> RH> RH> RH> RH> RH> RH>
Robert Heller -- 978-544-6933 Deepwoods Software -- Linux Installation and Administration
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Reply to
Robert Heller
Robert Heller spake thus:
Well, sure; what did you expect, that the sections of girder span would be curved? Of course not. The overall *bridge* is curved, not the structural members it's built out of.
The deck spans are made of straight spans as well.
Reply to
David Nebenzahl
The pictures are indeed not living proof that curved spans are possible. As I wrote before, short straight spans must be used.
Reply to
Erik Olsen
I am also getting the bandwidth has bee exceeded on file 2, so would like to see it eventually.
What I find interesting is that there is very much a mixture of lengths of plates. They consist of one plate of the exact size of the piers, with a larger plate span between.
I would like to see pics from the outside.
As I was the one asking about how to make a curved bridge for my layout, my need was help in that area. I received some very helpful tips from several people, & these photos help, Thank You All.
We also have them here in OZ but, obtaining photo's are no always easy, also most modellors seem to steer away from having curved bridges, & commercial curved bridges tend ti only suit 18' curves, & Marklin type track work. Also the piers we use are more often than not made from brick (early days) or concrete, later strengthened with steel piering in ghe middle of the spans. FInding commercial piers of suitable hieght has been difficult to almost impossible.
The only ones that I can find over here that look the part, are the Atlas ones in packs of 4but, they are all of the same hieght namely 3". I have a need of at least 4 with a graduation from 4" to 5". While I can somehow set shaped wood under the piers, I would have found it nice to have been able to get them commercially. It would be very nice if Atlas made these piers in different hieghts just like they do with their trestle pier sets.
Looking at file one, I will be looking at doing the same method, using a combo of ME 30 & 50 foot girder sets
Colin Hussey
Reply to
a6et
By a "curved bridge" I understand one whose spans are curved. This is AFAIK the common understanding among civil engineers. A trestle consisting of a series of straight spans supporting a curved deck is not a curved bridge -- a trestle is actually a series of short bridges.
AFAIK, there are no curved-span steel railroad bridges. There are however curved-span highway bridges; in recent years they have become fairly common. Some of these have curved multiple-beam spans supporting curved decks. Older curved highway bridges OTOH consist of straight spans supporting a curved deck.
Curved-deck masonry or concrete arch bridges generally consist of straight arches set at angles to each other, so they too are strictly speaking not curved bridges. However, the faces of the piers between the arches are usually curved to match the curve of the track, which tends to disguise the fact that the arches are straight. One could build conical arches, ie, arches wider on the outer side of the curve and narrower on the inner side. I would be consider these to be curved-span bridges, but I don't know of any examples.
The Swiss built a number of curved, pre-stressed concrete railroad bridges in which all elements of the bridge were curved as required by the curve of the track. These were AFAIK all built in the first half of the last century.
The problem with any curved bridge, whether it has curved spans or not, is that the load moves away from the centre of the curve and then moves inward as it crosses the span. At its furthest outward location, it tends to tip the bridge sideways. This tipping tendency is counteracted by widening the span and its supports, both of which increase the cost of the bridge. For this reason, railroads and highway departments avoid bridges on curves as much as possible, and will relocate the line to gain a straight crossing between curves if at all possible.
HTH
Reply to
Wolf Kirchmeir
In fact it's the other way around: A straight line is an arc with curvature = 0 (curvature is the inverse of curve radius).
Reply to
Erik Olsen
I think that the ability to create curved sections in a bridge is relatively new development made possible by advancements metallurgy and welding technology . If you lighten the photo you'll see that the sections aren't made of square panels welded or riveted with small pieces of steel as they were in the old days. They appear to be made of large pieces of steel the run the wholelength of the section.
Eric
Reply to
newyorkcentralfan
"Well, sure; what did you expect, that the sections of girder span would be curved? Of course not."
People tend to answer the question you actually ask NOT the question you think you've asked.
"The overall *bridge* is curved, not the structural members it's built out of."
AGAIN, no it's not. To be curved it would have to follow a circular or elliptical line based on a radius or a pair of radii..
Until very recently non linear plate steel bridges were made up of a series of isosceles trapezoids with two equal length sides and two parallel length unequal length sides.
Words and phrases have specific meanings, especially mathematic and engineering ones.
Eric
Reply to
newyorkcentralfan
That bridge is curved concrete on top of straight sections of steel as I see it. Still not a curved bridge.
-- Why do penguins walk so far to get to their nesting grounds?
Reply to
Bob May
Nope, those bridges are straight bridges with a curved trackwork on top. Look at each girder segment and you will see that they are indeed straight. Those girders are the bridge and the stuff (track and so forth) are the load that the bridge is carrying. As with the concrete load that the other poster has shown, the bridge itself is consisting of sequential straight segments that are wide enough to carry the load without tilting over.
-- Why do penguins walk so far to get to their nesting grounds?
Reply to
Bob May
On Tue, 9 May 2006 15:27:29 -0700, I said, "Pick a card, any card" and "Bob May" instead replied:
You're joking. Right?
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Curved bridge with curved rail. Any questions? -- Ray
Reply to
Ray Haddad
Bob, you may be sitting to close to your monitor and have gotten irradiated. That is a curved bridge as I have stood underneath it and attempted to take pictures to show all that *yes* indeed there are curved bridges. This thread came up a year or two ago and I made a special trip to take pix while I was visiting mom. I am going back to Spokane in a couple of weeks and will see if I can get better shots of the steel arc. I am about 50 feet below so I don't know what the Mavica will do and how much I can get.
Reply to
ctclibby
You're as blind as you are stubborn. The thing is curved. NOTHING on it is straight. Things have changed in engineering in the last 50 years, really.
Reply to
Jim Sherman
Curved deck with curved rail is all that photo proves; get closer underneath to show the girder sections, which are probably straight - but you can prove differently with an adequate photo.
Reply to
Steve Caple
The girders under the WV bridge (David Nebenzahl's post) are certainly straight sections, but the ones under the Spokane bridge (ctclibby's post) certainly look curved to me.
Reply to
Ken Rice

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