What is a hump yard in railroad terms?

Question

What is a hump yard in railroad terms?

Answer 1

It is a switch yard in a railway system that has a hump or steep incline down which freight cars can coast to prearranged locations, also called a gravity yard.

Answer 2

Dave is right on the money.  With humps of higher elevation, pneumatic "retarders" were employed to control the speed of the cars.  Extremely loud and a danger to hearing, and quite a nuisance to those living near a hump yard, also called a classification yard.

But, as the Union Pacific learned when rebuilding the old SP yards at Roseville, California, they removed the big hump and successfully eliminated the use of the retarders which were a source of constant complaint by the people living nearby.

But, they encountered a problem, that some of us "old timers" tried to tell them about.  The new hump there is a scant 20 inches.  But, during the summer, there are strong prevailing north winds, and now, though quieter, a siff wind stops empty cars.  Oops.

But, they told us SP people didn't know anything.  That may be true, but we knew dem cars ain't gonna roll.......

Answer 3

In the old days,  when they prepared a train,  they used smaller switch engines to move the train cars back and forth in the train yard,  with guys running around throwing switches so the right car would get to the right train.    

Now they used a hump yard,  also called a gravity yard.    

One engine slowly pushes the cars to the top of the hump where each car,  one by one is disconnected.   As it rolls down the hill,  remote control switching is used to direct the cars to the right train.   This saves a considerable amount of fuel as they only need one engine,  and saves a lot of lives as there are no men running around the yard where they could get hit.    

Due to the very low rolling Resistance of train cars,   with steel wheels on steel tracks,   the hump does not have to be very big and in some of the larger yards,  you hardly notice it.