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.
