Abstract :
This paper has been written so as to be of wide interest and to summarise current situations, and is therefore not highly technical, although the subject of the currently evolving systems towards which the discussions lead provides considerable scope for high technology. The paper starts by briefly setting out the assumptions as to the longer-term requirements, basically electric propulsion and automation. Rail rapid transit is discarded because it is a high-capacity system and personal rapid transit because it is too futuristic. This leaves, for serious discussion in the context of the title, various existing systems and their development as a background to the principal subject of the Review, i.e. automated guided transit. Sources of energy are referred to briefly and some tentative conclusions are drawn from informed sources as to the likely fields for battery-powered vehicles, synthetic-fuel internal-combustion engine, mechanical storage of energy and hybrid vehicles. If electric vehicles using a wired supply are assumed, it is now necessary to consider automation, and this is discussed briefly in relation to trolleybuses, trams, light-rail systems and fully automated systems such as l.g.t. and personal rapid transit. Various mechanical and electrical concepts available for l.g.t. systems are enumerated and tabulations made of more than 30 systems currently under development. This leads to a broad picture of the development status and of preferences for different concepts as regards such features as support systems, vehicle guidance, type of drive and control. The advantages and disadvantages of some of these variants are discussed, e.g. wheels/air-cushion/magnetic-levitation, different forms of vehicle switching and different methods of headway control. Electrical power systems are discussed, a.c. and d.c. and different types of motor and of power control. Mechanical features and train-control systems are discussed in general terms with reference to safety and - - system capacity. Capital costs of l.g.t. as compared with l.r.t. and r.r.t. from various sources are compared and discussed. The likely trends of development, as suggested by the considerions set down in the paper, are finally summarised.
