Essentials of the Absolute Block System - (1) Where trains are worked on the Absolute Block System - (a) no train shall be allowed to leave a block station unless Line Clear has been received from the block station in advance, and (b) on double lines such Line Clear shall not be given unless the line is clear, not only upto the first Stop signal at the block station at which such Line Clear is given, but also for an adequate distance beyond it; (c) on single lines such Line Clear shall not be given unless the line is clear of trains running in the same direction, not only upto the first Stop signal at the block station at which such Line Clear is given, but also for an adequate distance beyond it, and is clear of trains running in the direction towards the block station to which such Line Clear is given. (2) Unless otherwise directed by approved special instructions, the adequate distance referred to in clauses (b) & (c) of sub-rule (1) shall not be less than - (a) 400 metres in case of two-aspect lower quadrant signalling or two-aspect colour light signalling, and (b) 180 metres in case of multiple-aspect signalling or modified lower quadrant signalling.

Essentials of the Absolute Block System - 

(1) Where trains are worked on the Absolute Block System - 

 (a) no train shall be allowed to leave a block station unless Line 

Clear has been received from the block station in advance, and 

 (b) on double lines such Line Clear shall not be given unless the line 

is clear, not only upto the first Stop signal at the block station at 

which such Line Clear is given, but also for an adequate distance 

beyond it; 

 (c) on single lines such Line Clear shall not be given unless the line 

is clear of trains running in the same direction, not only upto the 

first Stop signal at the block station at which such Line Clear is 

given, but also for an adequate distance beyond it, and is clear 

of trains running in the direction towards the block station to 

which such Line Clear is given. 

 (2) Unless otherwise directed by approved special instructions, 

the adequate distance referred to in clauses (b) & (c) of sub-rule 

(1) shall not be less than - 

 (a) 400 metres in case of two-aspect lower quadrant signalling or 

two-aspect colour light signalling, and 

 (b) 180 metres in case of multiple-aspect signalling or modified lower 

quadrant signalling.