'B' signal box at Diamond Valley was built in 2003, and controls all main line movements from local Diamond Valley Passenger trains and express Special passenger trains to Yard shunting and passenger stock storage. All train movements from the two Diamond Valley station platforms are directed along the intended route by the use of a 80 lever miniature "interlocked" frame monitored on a large illuminated diagram driven by a Programmable Logic Controller (PLC).
This is the second Diamond Valley "B" Box. The first served DVR for many years but was ultimately eaten away by termites. The current signal box was patterned after the full size Ringwood signal box here in Melbourne.
The majority of signals and points are air operated. Two position Semaphore signalling incorporates a majority of the safe working at Diamond Valley. Signalmen are responsible for the correct routing of trains with trains regularly obtaining 30 second departure clearances.