Curved Bridge. Was Curved steel bridges--they exist AND (2002 ish ) Curved Bridges? - Latah Creek Spokane

ctclibby spake thus:

Also, please no crap about "that must have taken a hell of a bending brake to make them curved girders! And how do they do it without buckling the webs?" Obviously, some smart people have figured out how to make curved girders out of curved elements. How, I have no idea; I just chalk it up to magic.

Those are grast picturezs to do indeed show the curvature of the structural components of the bridge.

Following an earlier question on this subject, what sort of trains use this bridge?

Ken Rice spake thus:

Curved ones, naturally.

Do you have a picture of one? All the trains I've seen are made up of a number of straight segments. And how would they bend a train car into a curved shape?

I do believe that it was noted in the previous discussions that within the last say 20-25 years engineering and construction has advanced to the point that curved bridges are technically possible.

The are rare however and represent aproximately 14% of the railroad age [1830-2006]

If you're modeling any time period before 1980 it most likely ain't prototype.

And you *KNOW* some idiot is going to do a curved girder replete with rivets, plate and angles.

Best advice to a modeler is that if you're modeling a prototype that actually has a bridge like this go ahead but keep a set of prototype pictures handy.

If you're freelancing; stick with the conventional wisdom, that bridges don't curve they're made of rectangular building blacks with curving track on top of them.

Most successful freelancers are successful because they follow the most plausible not the exceptions to the rule.

Eric

Do you have a picture of one? All the trains I've seen are made up of a number of straight segments. And how would they bend a train car into a curved shape?

~~~~~~~~

Would they have to have separate left hand and right hand curved trains? Does the track only curve in one direction - thus making a circular track?

Hmm, this is beginning to sound like prototype following a model concept!

Val

Guys,

It does appear that the steel support structure on this bridge is curved. However, I think the poured concrete sections that they support would prevent this from being considered a steel plate girder bridge - more of a steel reinforced concrete bridge. There was no argument that curved concrete and masonry bridges exist, just that curved steel bridges were made up of shorter straight sections set at shallow angles to acheive the curve. These pictures are a great illustration, but they do not indicate that it is OK model a steel girder (either steel plate or truss) bridge with curved girders. Washington State does seem to have some unusual bridges, such as "Galloping Gertie" and some of the floating bridges on Puget Sound. I remember seeing a large multilane concrete highway bridge in the Seattle area that was supported on large timber piers or bents. I would've expected that a concrete bridge would rest on concrete or steel supports, not wood, just because of the tremendous weight involved, but then I'm no engineer. I guess the easy availability of large timber in the region made this economically feasible, but I'm sure if you modeled something like it on a layout, some "experts" would call you down.

Regards, Bill Nielsen Oakland Park, FL

Even though I was in Spokane for years, I could not remember when this bridge was put in place. I asked at trains.com forum and found that this bridge was started in 1971 and finished in 1972. Make sense as this is when all the major construction downtown started because of Expo74. They consolidate of all the ...ahem... other railroad stuff that was not in use by the consolidation of Great Northern, Northern Pacific and Burlington. Even to this day the alignments are still in place for the original GN main that crossed near Riverside State Park. Some of the flyovers out at Marshall can be seen. Nowdays, UP and BNSF are the mainstay.

And for just a little more info, when the tip-over occured on the Latah Bridge, UP used BN that heads South at Sunset Junction ( instead of Latah Junction ) then rejoined the UP main. ( UP: Ayer Sub, FishLake Jct mp 354.8, BNSF: Lakeside sub, Lakeside Jct mp 11.8 )

todh

I believe John Allen showed how he made the curved rolling stock on his layout in an article in MR many years ago. Of course, his were curved in the vertical plane rather than the horizontal, sagging due to truss rods that weren't kept tightened properly.

Finally some decent photos of a curved girders under a bridge. I guess that the engineers have succeeded in figuring out how to do the job without the structure falling apart. I do find it interesting that they find it cheaper to do a curved support rather than the traditional straight support. I would have expected that the straight girders would have been cheaper than going through the process of curving all of that steel. Then again, cost is really no object anymore when doing government projects so curved steel is possible to do.

-- Why do penguins walk so far to get to their nesting grounds?

No Bout Adout it.......the girders are curved. Curved girders have been around for years now ,that's why I can't understand some saying they didn't exist. Most however, are on highway bridges.

As I mentioned a few weeks back, a new bridge was just finished about a 1/2 mile from my house. When I posted that some even questioned my ability to recognize a curve. :-)...told me to go back and look again, get under it and look and also look from different angles. Ken

Did you go back and look again, get under it and look and also look from different angles?

Nope, because he finally found out that our planet is a dish and the universe is a hollow sphere ...

Regards,

Werner George Pflaum ... just can't believe this discussion - there must be something religious involved here ..

I would agree with what Bill says here. Certainly the bridge & steel members are curved, but I would think that the concrete mass would have a lot of influence in holding the steel in the arc.

Likewise, over the last "X" years there has been a great advance in the art of bridge building of all types, especially in concrete.

One question that I have on the plate gider, open deck types, is what is the situation at the joins, or ends where the plate sits on the piers? Is there a void to allow the next plate to sit at an angle for that span, or is there a section of steel plate bolted/rivetted in place.

I refer mainly to the outside of the span.

Colin Hussey

"> > Guys, "> >

"> > It does appear that the steel support structure on this bridge is "> > curved. However, I think the poured concrete sections that they support "> > would prevent this from being considered a steel plate girder bridge - "> > more of a steel reinforced concrete bridge. There was no argument that "> > curved concrete and masonry bridges exist, just that curved steel "> > bridges were made up of shorter straight sections set at shallow angles "> > to acheive the curve. These pictures are a great illustration, but they "> > do not indicate that it is OK model a steel girder (either steel plate "> > or truss) bridge with curved girders. Washington State does seem to "> > have some unusual bridges, such as "Galloping Gertie" and some of the "> > floating bridges on Puget Sound. I remember seeing a large multilane "> > concrete highway bridge in the Seattle area that was supported on large "> > timber piers or bents. I would've expected that a concrete bridge would "> > rest on concrete or steel supports, not wood, just because of the "> > tremendous weight involved, but then I'm no engineer. I guess the easy "> > availability of large timber in the region made this economically "> > feasible, but I'm sure if you modeled something like it on a layout, "> > some "experts" would call you down. "> >

"> > Regards, "> > Bill Nielsen "> > Oakland Park, FL "> "> I would agree with what Bill says here. Certainly the bridge & steel "> members are curved, but I would think that the concrete mass would have "> a lot of influence in holding the steel in the arc. "> "> Likewise, over the last "X" years there has been a great advance in the "> art of bridge building of all types, especially in concrete. "> "> One question that I have on the plate gider, open deck types, is what "> is the situation at the joins, or ends where the plate sits on the "> piers? Is there a void to allow the next plate to sit at an angle for "> that span, or is there a section of steel plate bolted/rivetted in "> place. "> "> I refer mainly to the outside of the span.

The outer plate gider is longer then the inner one. The pier would be at an angle. There is probably an expansion joint (space to allow for the girders to expand and contract. I believe there is some allowance for one end of the girders to move *lengthwise* a short distance -- one of the 'feet' is on rollers or slides or has a hinge thingy or something.

"> "> Colin Hussey "> ">

Robert Heller -- 978-544-6933 Deepwoods Software -- Linux Installation and Administration