Moving block signalling dynamics: performance measures and re-starting queued electric trains

From the functional point of view, signalling systems are generally evaluated on two basic criteria, namely their steady state and perturbed performance. The first of these essentially defines the capacity of a railway system, and the second relates to the cumulative disturbance experienced by all the trains on a system in response to a specific event, usually a delay imposed on a particular train. These two performance measures are investigated for both fixed-block signalling (FBS) and moving-block signalling (MBS) with other forms being included for comparative purposes. Steady state performance is analysed both mathematically and by using train movement simulators. The dynamic response to externally imposed disturbance is evaluated, using simulation studies. Some numerical measures of perturbed performance are proposed and the important trade-off between steady state and perturbed performance is discussed. A particular problem is the starting behaviour of a queue of electric trains when the leading train has stood still for a long time. This is the peak electrical demand problem caused by the characteristics of MBS. Peak demand reduction (PDR) techniques are thus proposed as solutions to the ʹstarting problemʹ and evaluated through simulation studies regarding peak reduction, delay and energy saving.