Junction in south-east London in the period 1843-1844. The signal control location (forerunner of the signalbox) was enhanced by the provision of interlocking (preventing a clear signal being set for a route that was not available) in 1856.

To prevent the unintended movement of freight vehicles from sidings to running lines, and other analogous improper movements, trap points and derails are provided at the exit from the sidings. In some cases these are provided at the convergence of running lines. It occasionally happens that a driver