The critical timing of door closing (RailEngineer)

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Much has been written and said in recent times about efforts to improve the throughput of trains on metro and inner suburban railways. Using CBTC [communications-based train control] has enabled 36 trains per hour (tph) to be achieved in each direction on London Underground’s Victoria Line. A dramatic improvement to passenger comfort has resulted and much of the severe overcrowding has been eliminated. Similar predictions are made for other LU Lines and also the full Thameslink and Crossrail (Elizabeth line) services when they reach full fruition.

However, a crucial factor in all of this is the ‘dwell time’ at stations to allow travelers to alight and board the trains. If the time taken for this overruns by more than a few seconds, then very quickly the delay to following trains builds up and the intended throughput becomes unachievable.

A service gap of more than three or four minutes means that crowds increase on the platform, extending the dwell time at every station as they attempt to board the first train, compounding the problem.

Although, in theory, drivers are not supposed to initiate door closure until everyone is safely on board, in practice, they occasionally have to start the closure process whilst people are still squeezing in, otherwise the train would never get underway.

A further factor is now influencing the process, this being to take account of the needs of disabled people, with legislation potentially increasing the dwell time period. Whilst the Rail Vehicle Accessibility Regulations (RVAR) of 2010 (its forbear being the Disability Discrimination Act) is intent on allowing additional time to board, the basis of this prescription may not have been scientifically derived, with perhaps a less than optimum situation developing.

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Written by Long Branch Mike