the prototype plans

I have used to make my bridge models from show the grades maintained over the bridges...

hope that helps.

md

No Vertical Curves

Keeping grades on a structure is not a problem at all.  I would avoid trying to put a vertical curve on the model though as I think it would be greatly exaggerated with all of the compression we have to put in our layouts.

Huey P. Long Bridge

There is no reason for a railroad bridge not to be on a grade. The additional loads can easily be calculated and the structure designed accordingly.

A good example for a bridge on a grade is the Huey P. Long Bridge across the Mississippi River near New Orleans which is on a grade of approx. 0.6%:

http://en.wikipedia.org/wiki/Huey_P._Long_Bridge_%28Jefferson_Parish%29

http://en.wikipedia.org/wiki/Huey_P._Long_Bridge_%28Jefferson_Parish%29#mediaviewer/File:Hueylongbridge.jpg

I apologize for my poor English. Being from Germany it not my mother language.

Regards, Volker

Bridges

Here are a few pictures of the Milwaukee Roads route from Haugen, Mt to Avery, Idaho. Grades and bridges all of the way. The first picture is the route.

As a kid I had the opportunity to ride in the cabs of the Little Joes over this route. The trip was breath taking. Next are some pictures of actual trains over the route and some pictures from the Hiawatha Trail which is a hiking trail over the old main line. Yep, bridges on grades, and curves.

The grades aren't 2 percent here, but there's nothing wrong with a bridge on a grade.

Thank you

Thanks everyone for the response and the photos.  I really do appreciate it.

Mike 

All bridges are on grades

There must be many bridges truly level across their lengths.  However, on railroads in mountain country, they would be a rarity.  There is no reason to interrupt a grade taking tracks through a pass simply because there is a gully or re-entrant that must be crossed and a bridge placed there.  To alter the two approaches to a bridge so that the bridge is level on what should otherwise be a consistent grade reduces the effective altitude change of the entire grade in a way that is counterproductive.

@ Mike

Funny thing I asked this question maybe two years ago.  I was curious if heavy braking on the down slope could damage the bridge.  Do you know railroads sold existing steel bridges to other railroads? I will see if I can find where I read that.  Can you imagine the load that would make?  If you really want to see some grades on bridges take a look at this....

https://www.google.com/search?q=Morenci+southern+railway+photos

It is my latest research project for an narrow gauge model railroad.

Den

" I was curious if heavy

" I was curious if heavy braking on the down slope could damage the bridge. "

   Heavy braking can damage almost anything if the cars fall off the rails :> ) But braking force applied to a bridge would be mostly lateral in the direction of travel and limited by the traction of the wheels so I'd imagine the longitudinal structure components could handle it just fine, it's probably considerably less than the margin of error built in to the vertical components....DaveB 

As said before the brake

As said before the brake force on the rails is limited by the friction of the blocked wheel on a steel track. On a downgrade the part of the weight perpendicular to the track and the friction are a bit smaller compared to level track but there is an additional force parallel to the track. So the stopping distance gets longer. The influence of a train going up-hill is greater as the locomotives have to pull a larger weight caused by the grade when on the bridge.

These longitudinal forces are no problem for a bridge just something the civil engineer has to consider when doing the structural analysis.

Regards, Volker

There's a prototype for everything.

someone once said you can model anything you want, and somewhere there's a prototype for it.

@ Montanan, Lucky bugger

@ Montanan, Lucky bugger getting to ride on Little Joes.  Alas, I was a few years away from creation at the time.  We are trying to replicate some of Lines West on the club layout.

As for rail on bridges and grades, sometimes the rail does shift on hills, even with anchoring.  The rail tends to slide down the hill, account of both trains pulling uphill, and trains braking on the downhill.  More factors for the engineering department to consider.

Bridges on Grades

A resounding Yes! A great example is the Foss River Bridge in Washington state. On a 2% grade it is a compound curve going up, changing continuously from 6 degree to 10 degree curvature! It is Steel girder spans on bent towers, quite high off the ground. Definitely worth checking out.

Grades and rail...

Rail moves downhill: Braking on descent, and tractive effort on ascent. Also, the up/down flexing of the rail as the rolling weight moves over it loosens spikes, which further allows downward creep. This effect is more pronounced on stick rail as opposed to welded. Sometimes there are places that stick rail will move downhill enough that it can create a stripped joint. I've railroaded on several divisions where this was an issue.

Andre

Here is a bridge on a grade

Here is a bridge on a grade with a town under it.

And it has a train.