Definitions Flashcards
Absolute block section
The line between the last stop signal (can be an section signal or intermediate block home signal) controlled by one signal box and the home signal controlled by the next signal box
Principle of absolute block
To prevent more than one train being in a section on the same line at the same time
Station limits
The line between the home signal and the section signal controlled by the same signal box in the same direction of travel
Block Signal
A stop signal that controls the entrance to or the exit from an absolute block section or an intermediate block section
Home signal
The first stop signal controlled by a signal box that controls the exit from the absolute block section
Section signal
A stop signal controlled by a signal box that controls the entrance to an absolute block section or an intermediate block section
Intermediate block home signal
A stop signal controlled by a signal box that controls the exit from the intermediate block section and entrance to absolute block section
Intermediate block section
The line between a section signal and intermediate block home signal controlled by the same signal box in the same direction of travel
Clearing point
The point beyond the home signal up to which the line must be clear before a train can be accepted as shown in regulation 3.4
Purpose of TPWS
To stop the train by automatically initiating a brake demand where TPWS equipment is fitted
Purpose of AWS
Provide driver with an audible and visual indication of whether the distant signal was clear or at caution
OSS abbreviation
Overspeed sensor system
TSS abbreviation
Train Stop System
Definition of a complex failure
A failure of power operated points which needs more points ends to be set or secured than a simple failure. It includes all failures that affect switch diamonds or swing nose crossings.
Definition of a simple failure
A failure of power operated points that need one of the following to be set or secured -
- A single point end
- A single point end and co-acting trap point.
- Both ends of a crossover.
