The U.S. Army Corps of Engineers, of whom I worked for has developed free software to assist in planning rail construction and rehabilitation. These programs have only been available with the last five years. Called AREMA track design criterion. They have a downloadable PDF discussing vertical load pressure, load limits, and progressive high-load roadbed deterioration. And more importantly, estimating man hours and equipment hours required for various repairs, much as in the old fm 5-35.
http://pavement.wes.army.mil/pcase.html
The URL only seems to work when you type it in and not use the hypertext transfer link.
There are several other Corps of Engineer rail repair PDF's available for download.
AREMA publishes "The Practical Guide to Railroad Construction" which should be a must-have for any museum with proprietary trackage. And those considering rebuilding the Churchil line. A tremendous amount of information is available these days regarding rail repairs, estimates of man and equipment hours to repair, and forecasting lifetimes of track that were unavailable in 1929. We no longer need to rediscover the wheel or make repairs by the seat of our pants.
Incidentally AREMA publishes a "portfolio of track plans" which should be of great interest to any P:48 modeler.
