Sydney Trains assumes that this relates to a protection officer visually identifying a train passing a worksite. Identifying an existing train within a section using this method can be problematic for a variety of reasons, including; identifying small target numbers on suburban rolling stock, reconciling stock numbers with train numbers etc.
The current rules do not specify a particular method to be used to identify trains, but instead allows the signaller some autonomy in how they would do this. It is believed that the coded ASB process requirement to establish and record the location of the last train to pass the protecting signal will address this action.
The Australian Transport Safety Bureau is satisfied that the ‘coded Absolute Signal Blocking process’, if completed and implemented, will improve the way signallers and Protection Officers (POs) identify trains to each other.