Sidings at the summit of grades were also designed to let underpowered trains cut a portions of there trains at the bottom of the grade, then take what would fit in siding up the grade and store, then go back down, get train cars left at bottom, then go back up the grade, double to the siding and move on down the hill with all the train in tow. We call it doubling the hill. Alot of extra work for crews, very undesirable account carrier dosen't want, or have power to assign to underpowered trains.
John
