CHALLENGING ESTABLISHED RULES FOR TRAIN CONTROL THROUGH A FAULT TOLERANCE APPROACH

The operation of a rail network is safe-guarded through the use of train control and protection systems, in particular in the forms of block signalling and interlocking. To ensure the absolute safety of trains and passengers, the signal at the entry to any track block is set to red unless the block is completely ready to accept the next train, e.g. the points must be confirmed to be set in the correct directions and the track is confirmed as unoccupied. This means that a train approaching such a red signal must start to decelerate and prepare to stop from two blocks in advance, even though there may be minutes (or at least many seconds) before it arrives at the 'red' signal, by which time the block ahead will be cleared (as planned) in most normal operating conditions. The use of clearly conservative speed profiles on approaching such blocks has a knock-on effect on other trains and can cause a network to operate at considerably less than its full achievable capacity. In the foreseeable future, train control systems will be replaced by state-of-the-art railway traffic management systems, traditional fixed block signalling will be abandoned and there is scope for intelligent speed adaptation for trains similar to that proposed for road vehicles. Such ICT-led innovations will offer significant enhancement to network capacity, but only if the conservative 'rules of the game' are challenged at the design stage.This proposed research will develop a fault tolerant approach to the design and operation of the rail network, by integrating track design (e.g. the track layout, the positions of points and signalling blocks) with dynamic routing/scheduling, optimised using a novel evolutionary computational approach particularly suited for combining multi objective optimisation with safety/risk management. The term fault tolerance is used here in a broad sense, to represent any abnormalities or unexpected events in operations or equipment. Enhanced fault tolerant capability would provide safety assurance so that, in normal operating conditions, trains can adopt much faster speed profiles when approaching a 'to-be-cleared' signal block at stations and junctions than those currently permitted, effectively turning the status of 'be ready to stop' to that of 'proceed with caution'. In the rare event of a 'fault' in the system, e.g. a train in front fails to move out a signalling block as expected or a switch fails to operate as required, the train would be re-routed to take an alternative path. Relevant scenarios might include the management of right-turn junction conflicts, train routing through complex junctions at station approaches or the re-allocation of trains to alternative station platforms. Increased capacity will be achieved through improved capability to handle disturbances and/or reduced operating constraints, without compromising the overall integrity of the system.

This study proposes a novel approach for train control and protection, which has the potential to challenge traditional operation and safety rules in railway, question the way of thinking and help change the conservative mindset in rail operations. The novelty and adventure of the research and potential benefits, in terms of increased rail capacity, reduced travel time and improved attractiveness for modal shift towards more use of rail transport, promises high impact outside of the academic sector, particularly in the context of the worldwide interest in technologies for future public transport. The proposed feasibility study will have wide-ranging and significant impact across the Public, Commercial/Industrial and Academic sectors. Direct beneficiaries from the research will include rail network operators and train operating companies who can expect increased revenues from the increased capability to handle more trains on the network, manufacturers of train control and protection equipment from new business opportunities, and passengers and freight transport users at large for shorter times for travel and/or delivery of goods. The research will be of direct benefit to public transport makers (in particular the Department for Transport) and enhance the effectiveness of public policy with respect to the public/private transport balance and major infrastructure investment. It will also be highly relevant to low carbon policy makers, e.g. BERR bodies and other bodies promoting low carbon technology developments such as the Carbon Trust, in terms of setting and achieving national and global emissions and sustainability targets. Overall, the technology has the potential to facilitate the increased use of public transport (and hence reduced journeys using private cars and road congestion) and help achieve global carbon and emissions targets, with consequent impact on the wider society at large.