Might be better to post in Structural or Railroad forums. My preference would be structural. Others are more qualified to answer this.

Dik

For lateral surcharge against walls, I have never seen any railroad require a "dynamic analysis" for the E80 load. Some railroads, AMTRAK for sure, require multiplying the static, vertical, area surcharge by an impact factor. AMTRAK's impact factor is 1.5. The requirement is to take the 80,000# axle load, multiply it by 1.5, and then divide that 120,000# load by the 5' axle spacing and the 8.5' tie width. (80,000# x 1.5)/(5.0' x 8.5') = 2823 psf vertical strip load using a Boussinesq analysis to get the lateral pressure.

www.PeirceEngineering.com

Same as PEinc, I've not seen it done (though my experience here is limited).

If you know the rail design speed in the area of your structure, surely you could develop a step function load for a few probable train lengths.

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The name is a long story -- just call me Lo.

I will not try to advise on this one other than to mention something I once did that was quite interesting to me. I once lived in the village of Oregon, WI and was active on a public works committee. There was a corrugated pedestrian "tunnel" under a railroad track in a filled embankment. The culvert section had been distorted significantly during installation, to the extent that the village decided to barricade it off in case of collapse. Cover over the culvert was about 3 feet. Train traffic was light, but mainly an occasional train of loaded iron ore cars. I installed reference points in the tunnel for receiving tapered ends of a measuring device using dial deflection gauges as used in a machine shop. Both vertical and horizontal dimensions were measured. I was able to get one planned measuring event where I could control just which axle was over the reference location. Of course the crew engineer was not too pleased with this "fooling around" using his time, but the conductor, in charge of the train, was down in the tunnel with me and directed the engineer by radio. The result of these stationary readings showed the axle loadings of the locomotive to be significantly less than those of the loaded rail cars. Once the train got under way, one could use the dials to see just what was happening with deflections as the loaded axles went by. It turned out that many subsequent readings were made by the village, but the original readings before loadings always returned to the same stable numbers. The result: the pedestrian tunnel was opened for use.