This paper describes how London Transport endeavours to evaluate the optimum train performance characteristics necessary to meet the peak service requirements for a given line at minimum total cost to itself and hence to the passenger. The basic factors affecting train performance on a subway system are outlined, and the practical limits to the attainment of ideal performance are described in detail, with particular reference to maximum acceleration, and the high additional energy costs of increasing maximum speed to save time on short runs. A detailed examination is then made for the Victoria Line service, using a digital computer to assess the net effects on capital and running costs of progressively increasing the proportion of motored axles on the Victoria Line trains, and determining whether the consequent improvements in performance are sufficient to operate the same service with fewer trains. It is concluded that for present London Transport conditions the proportion of driving axles cannot be increased beyond the present figure of 50 per cent without increasing total costs, and this is of considerable interest to London Transport in relation to the more heavily motored formations favoured by many Continental and American subways. It is shown that appreciable energy savings can be realized on the Victoria Line by the use of the coasting control feature of the Automatic Train Operation scheme and by the incorporation of the ‘hump station’ principle first used on the Central London Tube in 1900. A comparison is made of the merits of using the hump station principle on a hypothetical new tube line and/or increasing the proportion of driving axles, and it is concluded that the use of even a limited degree of gravity assistance will enable both rolling stock and energy to be saved for a given service, with no increase in the proportion of motored axles.
Analysis of ATO System Operation Scenarios Based on UPPAAL and the Operational Design Domain
