ABW Flashcards
What is ABW?
Absolute Block Working
A method of safe working to allow only one train at a time between the Absolute signal and the defined end of the Block point.
When is ABW used?
When maintenance machines move through a section
When rail traffic movement fails to be detected by the signals, ie when signals fail
Whenever deemed necessary
What is the objet of ABW?
To prevent more than one train movement in the defined Block working limits at the same time
To prevent trains from entering the defined block working limits whilst a preceding train is occupying it.
How is the object of ABW achieved?
Once train has entered, the signal is ‘blocked/sleeved’ to stop by placing a blocking command on the signal
The blocking command can only be removed once the train has arrived complete at the end of the Absolute Block Point.
What are the two types of Block Working?
Between two controlled signalled locations (A Block Section)
Between a controlled signal location and a nominated clearance point
(flaggy)
What classes of signals are Absolute signals?
Home, Dwarf, Disc
(controlled signals)
What speed do you do in ABW?
Track Speed
What happens when ABW is used on Single Line Systems?
The opposing Departure signal must have blocking facility placed on the control switch
If the signals in advance are controlled from another signal box, the two signallers must confirm arrived and complete before blocking facilities can be removed.
