Jack Delano visited the AT&SF interlocking tower at Isleta, New Mexico in March of 1943. Shown here is the tower operator lining the route for an approaching train. Each of those levers controls the route through a track switch and it’s attendant signal in the maze of trackwork below. The board above him shows the track diagram of everything under his control.

At left one can see just a bit of a wall mounted telephone, and below that the wye shaped pole used to pass orders to a train crew. At right the ladder for servicing the train order signal can be seen through the window.