Real Time Information uses GPS (Global Positioning System) technology to monitor the movements of buses and therefore can accurately predict the arrival at bus stops (for example 5 mins).
Scheduled times are where real time information is not available and the
times shown are of timetables
produced by the operators ( for example 1215). While the bus operators
endeavour to keep to the running times they cannot predict every eventuality
and late running of services cannot always be avoided.