Ten90 Solutions LLC

I received a correction from a colleague.  He writes:

I did want to mention that during my tenure on the AREMA C&S Technical Committees, every single meeting the chair uttered words to the effect of the point below sternly and loudly:
 
“AREMA does not write ‘standards’—railroads and rail transit agencies write standards.  AREMA writes recommended practices and recommended practices only, which the railroads and rail transit agencies are free to modify as they deem fit to establish their standards so long as such standards comply with FRA regulations.”

I understand the difference and appreciate the correction. 

As long as we're making corrections, I stated earlier that FRA does not mandate the speed restrictions through curves.  Technically, that's correct.  However, practically.... FRA provides a formula in 49CFR 213.57 (b) for calculating the maximum allowable posted timetable operating speed for each curve.  This maximum velocity is derived from the relationship of the actual elevation of the outside rail of the curve plus the qualified cant deficiency of the equipment type to the degree of curvature. 

Also of importance here is the identification of "maximum allowable posted timetable speed."  FRA clearly distinguishes this timetable speed, MAS, from a signal determined and defined speed.  The latter requires enforcement by and when automatic train control systems are in use, while the former, being a timetable speed, requires no such automatic enforcement. 

dms 5/21/2019