Runaway cars smash into harbor terminal in Oslo, 3 killed

[Bob C]

Some are, it seems, unfamiliar with "Hump" classification yards...the cars air brakes are bled out, and hand brakes released. Cars are then pushed (by a locomotive) over a hill (or "Hump"), uncoupled - sometimes in motion, to roll free down an engineered grade through power retarders (pneumatic usually), controlled by an operator and/or a computer to adjust speed, through ladders of switches into a class track, for a specific destination or other purpose. Cars are "retarded" so they will roll with appropriate force - enough to reach the end of available track length, and couple to cars already on the track. When the "class" track is full, or when a train is made up including that destination, the cars are picked up by a switch engine, and placed on a "departure" track, and "sufficient" hand brakes set to arrest movement. The car department then blocks and "Blue-Flags" the track, couples hoses, inspects the physical condition of the cars, tests the function of each car's air brake, (an Initial Terminal Test) and reports the train ready for power. boppa, the Australian brake systems must be somewhat different - from your explanation, a "Hump" yard operation, and a lot of other switching we do, could not be accomplished. The volume demands of a main classification yard can be 600 to 1000 cars per hump per 8 hour shift, impossible productivity with all "on-air" movements. Guess I've still got a lot of new stuff to learn about ! I'd better hurry... Bob C.