THE SIGNAL BOX

BLOCK SYSTEM

BRITISH RAILWAY SIGNALLING INSTRUMENTS

Southern railway signalling instruments

Southern Railway Three-Wire Three-Position block instrument

Southern Railway Three-Wire Three-Position block instrument

The Southern Railway inherited a wide range of primitive block systems with the companies it absorbed. Aside of the main lines which were mostly signalled (in the London area, at least) by Sykes Lock & Block, the network was mostly signalled by a range one-wire two-position instruments.

The Southern set about developing a standard three position block, which was built to chunky standards. Indeed, it may be that early ones were converted from redundant Sykes instruments.

Nevertheless, they proved a sturdy and reliable instrument, and large numbers were built for installation on primary routes.

Over the years, as resignalling has taken place, examples have cascaded to lesser lines, but it wasn't until the 1980's that two position working on the Southern Region finally became extinct. However, by following this principle, the Southern Region never needed to adopt the inferior BR standard block instrument.

The example illustrated here is at Canterbury West, more details of which will be found in the Photo Gallery.