For a brief period in 1966 Burlington and Rio Grande have been pooling motive power on a single freight west from Denver. Here on March 27 CB&Q 953 leads a five-unit matched set of GP30’s up the twisting 2-percent grade leading through the Grande’s famous Little Ten and Big Ten Curves. In the background the caboose is just passing Rocky (formerly Arena), where a short branch sets off to serve Dow Chemical’s Rocky Flats plant, a super-secret facility that, unknown to all but a few, remanufactures plutonium ”pits” into triggers for hydrogen bombs. The Cold War is still frosty, and the sprawling facility on its lonely plateau is a vital link in the nation’s nuclear weapons program.