The loading of coal and refuse material is mechanical and one man can load a train. Of the source of the material nothing is observable except the end of the chute. Cars delivered to their destinations pass on to higher levels and trains are made up of cars that descend on elevators from shipping rooms above. There are no interferences, no crossing gates, no other kind of traffic, no congestion, no delays. The tunnels are lighted at all connections and elsewhere when other than the train lights are needed.
Signal lights protect the trainmen when delivering or switching cars.
Glass reflectors at all intersections give warning of an approaching train from lateral lines. The trainmen know the corners and it doesn't seem to matter that each one is exactly like all the others. It appears that a tunnel car carries about as much of a load as a motor truck. In the tunnels, there is an average of about 300 train movements a day and a train is from ten to fifteen cars. The movement of freight in the tunnel is about equal to 5,000 motor truck movements on the streets.