detection, brake and stop blocks
Automatic control of a DCC layout controlled
by Railroad and Co demands that the system knows were the trains are at
key points and that messages can be passed to the locos to slow down and
These are achieved by a block system.
Detection blocks are provided in a similar
manner and will read once a locomotive enters it. It is also possible to
detect that the last vehicle has entered the block by placing a small
resistor between the last pair of wheels. Due to the small size, this has
not been done on County Gate and we rely on the integrity of our Greenwich
The cut rails for blocks must always be on
the same rail (control rail). Once the first current collection wheel
passes onto a block, the message to slow down, stop or start is received.
Positioning of the stop block is critical to ensure that all trains stop
in the correct positions. With conventional locomotive hauled trains, this
is not difficult. Our railcars on the other hand did present a problem as
the current collection is from the central motor car. To solve this
problem, the bogies on the passenger cars had to be modified so that there
was current collection from the control rail.