Table 3 2 -6

Present Status of Northern Line

Track: D = Double Track, S = Single Track, C. Loop = Train crossing Loop, P. Speed = Passing Speed

Signal: CL = Color Light Signal, SM = Semaphore

Blocking System: A1 = Automatic Blocking, A2 = Semi-automatic Blocking, A3 = Tokenless with Color Light, A4 =Tokenless with Semaphore, B1 = Ball Token

Interlocking system: A1 = Relay Interlock

A2 = Electro-mechanical, but point or signal are electrically controlled lever.

A3 = Warner, Home, Start signals are mechanically interlocked.

A4 = Either Home or Start signals, or Home signal are mechanically interlocked.

B = Key locked manual point with lever contolled Home signal

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