Historical information
Electric staff - Electric staff instruments
The staff and ticket system was still too inflexible for busy lines, as it did not allow for the situation where the train intended to carry the actual token was cancelled or running very late. To provide for this, the electric train token system was developed. Each single-line section is provided with a pair of token instruments, one at the signal box at each end.
A supply of identical tokens is stored in the instruments, which are connected by telegraph lines.
A Staff can be removed from one instrument only if both signalmen co-operate in agreeing to the release. Once a Staff has been removed, another cannot be removed until the token which is "out" is replaced in either instrument. (There are variations on this sequence of events.) By this means, it can be ensured that at any one time, only one token is available to be issued to a driver. Staff belonging to adjacent sections have different configurations to prevent them being inserted into the wrong instrument.
Nevertheless, in the Abermule train collision in 1921 and lax working procedures allowed the safeguards provided by the electric Staff system to be circumvented; a driver was handed a Staff for the wrong section, and without reading the information listed on the staff, proceeded on the mistaken belief that the Staff was correct. To prevent this, it became a requirement in the UK for the signals controlling entry to the single line section (starting or section signals) to be locked at danger unless a token has been released from the relevant Staff instrument.
Significance
Historic - Victorian Railways Electric Staff Instrument
Physical description
Electric Staff Instrument made of Iron , Brass and Glass
