201604 – Burns – Movement Authorities – A Systems Framework

This paper on Movement Authorities is one of a series on the various elements of the Generic Systems Framework (see figure 1). The issuing of Movement Authorities is distinguished from the setting of a route and the general pre-conditions for the issuing of a Movement Authority stated.

Movement Authorities are shown to be found in all safeworking systems and having characteristics which are common to all of them. The process for issuing a Movement Authority may be characterised as the formation of a contract between the train and the interlocking.

Looking at fixed signal systems, the signal is found to fill three distinct functions, one of which is the communicating of movement authorities.

Turning to ERTMS and CBTC systems, it is shown that their central functionality is of a nature that does not require treatment as a movement authority. Benefits can be obtained by recognising the different natures of the three distinct functions which are replaced when ERTMS and CBTC systems replace fixed signals, and drawing the signalling requirements around those distinct functions appropriately.