Far from being rendered obsolete by car and bus, or squeezed out by rising costs, the pace, of metro construction has accelerated dramatically through three decades-· and this trend is continuing. Once categorised by planners as suitable only for the most densely travelled corridors, urban rail is now appreciated as offering a continuous spectrum of choice from fully segregated metro and regional rail systems through to the streetcar or tram. Provided large and medium-sized citied have sound transport policies, there will usually be an important role for rail transit.