Not really.
By example, The Southern Pacific ng operation out of Mina, Nevada, on the old Carson & Colorado to Keeler in the Owens Valley had a variety of rail in 1934. The smallest was the 35 lb. original rail from 1882-83. Various parts of it had been replaced with 60-62 lb. rail.
In 1882 an on-line soda and salt works wanted some rail for its tram line out on the often dry lake bed. H. M.Yerington was of the opinion that that tram line did not require any of the 35 lb rail that the C&C was laying -- 16 lb rail would be good enough for the tram line.
Jerry -- as always -- has provided a good answer about the Rio Grande.
I think the White Pass & Yukon Route has been installing 116 lb relay rail.
Brian Norden
edited upon seeing Jerry's slightly earlier reply.
Edited 1 time(s). Last edit at 01/05/2011 10:50PM by Brian Norden.