For one of my enginnering classes I have to design a railroad bridge. The only specifications are that the bridge must span a 100 foot wide river and have a height of 38 ft above the water to the bottom of the tracks. Any help would be greatly appreciated and needed.
Thanks
Which Engineering class? Statics?
The Engineering class is a graphic Auto CAD class. But the bridge has to be buildable in real life also, so i have to use the correct size beams and supports made out of the correct material for the span.
Doesn’t sound like you have too many restrictions. Can we assume that you’re bridging a valley at least 38 feet deep? or will you have to approach that height from just above water level?
I can recommend two books, if you can find them (both are probably long out of print):
The Beauty of Railroad Bridges, by the late Richard J. Cook (Golden West, 1987)
and
Landmarks of the Iron Road, by William D. Middleton (Indiana University Press, 1999).
As for your thread title, I was about to recommend that you move your project off the railroad bridge![;)]
This is a hard one but look at books and go to the history.com because they had a show on bridges and it had a british rail bridge made of steel and suppose to be the strongest in the world.
IF you have more restrictions it can be easier to design but there are a few exception.
Try different types of bridges like tressel, suspension, etc…
Try finding pictures of rail bridges and see if something jumps up to you.
The easiest is a semetrical bridge from one end to the other so do that if you can. Any other of unsemetrical bridges will take longer, more mesurements and might not work as well. So keep the sides the same if you can.
I know this because i had the same class but had houses and other things to do.
[:)]
RR bridges with 100 foot spans are actual rather rare - I would check for examples of bridges crossing the Mississippi and other large navigatable rivers. The check some of the steel supplier’s websites for standard section sizes, etc.
dd
If you want to get into the details of bridge design, the current resource is the American Railway Engineering and Maintenance of Way Association’s (arema.org) Chapter 15 of the Manual for Railway Engineering. That will give you all of the design criteria currently used for a steel structure. Look in Chapter 8 for concrete and foundations. However, they only sell the manual, so unless your school has a copy or you know someone at a consultant that does railroad bridge design work, it will be tough to find.
The classic resource is J. A. L. Waddell’s “Bridge Engineering” from 1916. That is the bible for railroad bridge engineers. That will be tough to find also, unless you have access to a very good technical library. Just saw a copy listed on abebooks.com for about $700.
If you just want to find some quick info, the previous mention of Middleton’s book is a good place to look at pictures, but has no real detail about design needs.
What you are probably going to end up with for that span length would be through plate girder with webs about 10-12’ high and the top of rail about 1/3 of the way up from the low chord. Do you have to design the foundations too?
I’m not a bridge designer, just built many of them. Depending on where in Wisconsin you are, you should be able to find several examples to look at. La Crosse has several TPG’s, DPG’s, trusses, swing spans and Bascules on the CP line that I have a passing familiarity with. 1700’ of bridges in 3500’ of railroad over four different waterways.
Good luck with your project.
If you Google for West Point Bridge Design you will find a freely available program from the US military academy that is used in a student contest to design bridges.
I think you will be able to use that program to model and test some bridge design(s) that might be fairly close to your problem specification…
You might find the reference bridge design books at the library of the engineering school of your nearest large university. Obviously, if you are in the Chicago area, a visit to Illinois Institute of Technology would be helpful, in the Boston area, MIT and Northeastern U., New York might be Stevens Institute in Hoboken, Cooper Union and Columbia U Engineering in Manhattan, others could be Rutgers U. in Trenton, RPI in the Albany area, Cal Tech, etcx., etc.
Be sure to factor in the necessary safety factors, and with a solid deck bridge include snow load. Figure track space fully loaded.
Thank you everyone for all of your ideas. I will have to follow up on them. I have some added information also. I asked my professor about more specifics and found out that I can make any other restrictions that i would like to add to the bridge, except that the river must remain a navigatable river, and the bridge must be feasible to build for a real railroad. I also found out that I do have to design the foundations as well as the bridge itself. I have looked up some of the general clearance regulations so that i can be sure to design a bridge that a train can travel through. The 100 feet is the total length of the bridge and the approach will be level with the bridge and the river and river valley will slope down under the bridge (possibility of building a trestle bridge in the valley and then a shorter span over the river itself?). Also thought of having a bridge over a river in a canyon. I think I will go and try some of the ideas that you have mentioned to me, once again thanks a lot for all of the ideas.