the bowstring steel arch Park Square Bridge. An underpass takes the tram underneath the busy A57 roundabout outside the University of Sheffield. Tram stop design The Supertram has 50 tram stops, which are generally long and deep and are of a network-wide standard making them easy to understand and use. The design incorporates recommendations made by the Cranfield Institute of Technology who studied ergonomics for both able-bodied and disabled users. The platforms are high, with a 1:20 slope. The platform edge comprises a wide light-coloured textured paving with strips of wide edge warning tactile strip. Directional guidance tactile paving crosses the width of the platform to coincide with the tram door locations. Power supply Supertram is powered through 12 electric substations and fed through cross-section overhead line equipment (OHLE) wire. The substations convert the 11 kV AC supply into supply into the overhead. The 12 substations are situated as follows: Blackburn Meadows Carbrook Nunnery Square Park Square Arbourthorne Gleadless Townend Birley Crystal Peaks, Ochre Dyke Lane Halfway, Eckington Way University, Brook Hill Langsett Road, Capel Street Middlewood The overhead line equipment depends on the location. If the tracks are close together, central poles with 'steady' arms on each side are used. If the tracks are further apart, poles on either side with span wire are used. With aesthetics in mind, a minimum number of traction poles are used and whenever possible the wire is anchored onto neighbouring buildings, and blended into the structures as far as possible, after talks between Supertram, the City Council and landlords. The contact wires are twin cadmium copper ones, twin wires being necessary because of the high installed power rating of the trams (1megawatt). The regenerative braking on the tram feeds current back into the wires. Depot There is a single depot, located at Nunnery Square, which occupies former carriage sidings alongside the Sheffield to Lincoln railway line. It was designed and constructed by Balfour Beatty on of land and consists of a three-line workshop building, six stabling sidings, a turning loop, engineers sidings and sundry equipment. Before the arrival of Supertram, the site was already dedicated to the railway industry. Nunnery engine shed filled most of the site whilst lines of the Midland Railway, Great Central Railway and London & North Eastern Railway irrigated the area and served collieries. Rules of operation The rules of operation of the South Yorkshire Supertram are similar to