Modelling as a tool for system engineering on the Docklands Light Railway

摘要

The Docklands Light Railway is now in the final stages of completing a comprehensive upgrading programme which will see its design capacity raised from an original level of 15,000 passengers per day to 24,000 passengers per hour. To cope with this increase in capacity it has been necessary to add extra track, increase the vehicle fleet site and replace the fixed block signalling system with a moving block signalling system. The result is a railway of greatly increased complexity. The prime contract, which integrates the resignalling contract with the new vehicle contract system and demonstrates agreed levels of system performance, has been awarded to a joint venture company, Brown and Root, Booz Allen Limited (BBJV). System performance is measured by an indicator called system service availability (A/sub s/). A/sub s/ is calculated by two methods; one is based on analysing significant measurable service disruptions; the other captures the net impact of all service disruptions. Both methods are applied to each day's service and the lower (worse) of the two is taken as the result. To predict likely system performance BBJV has developed a PC based reliability, availability, maintainability and dependability (RAMD) model. The model accurately simulates the operation of the railway and utilises a user defined set of subsystem reliability data to predict the likely value of A/sub s/.