Re: FRA Par 213.9

My freind PRSL has often adressed this, but just for kicks I'll chime in and state that the FRA regs refering to Class 1, Class 2 etc. don't legally apply to track gauge less than 56 1/2". That is not to say one can not use these standards as general guide lines on a volunteer basis. My question then is are these standards/guidelines appropriate from a scientif/engineering standpoint with respect to the relationship of track conditions to speed, for 36" gauge equipment.
Not to beat a dead horse as this subject has been discussed here before at least superficially, I have to wonder if there are some issues here that folks with a civil/mechanical engineering background should wade into at some point. What I am thinking is the applicability of these speed standards considering that the center of gravity and weight of Narrow Gauge equipment may be significantly different than std. ga. eqipment. The narrower gauge might be sort of in proportion to the reduction of center of gravity and overall weight of equipment, making all things equal, or not. It seems to me someone needs to get scientific about this at some point.
Did the Rio Grande ever have any published standards to guide their track men on the narrow gauge, that addresed track speed with respect to track condition?