Alimentation par le sol

Ground-level power supply, also known as surface current collection and Alimentation par le Sol (APS, which literally means feeding via the ground), is a modern method of third-rail electrical pick-up for street trams instead of more common overhead lines, thus it is one of the methods that could allow construction of catenary-free light rail system. It was invented for the Bordeaux tramway (Tramway de Bordeaux), which was constructed from 2000 and opened in 2003. From 2011, the technology has been used as part of other systems around the world, with Reims Tramway, Angers tramway and Dubai Tram all having adopted the technology.

Ground-level power supply is used, primarily for aesthetic reasons, as an alternative to overhead lines. It is different from the conduit current collection system (which was one of the first ways of supplying power to a tram system) as it involves burying a third and fourth rail in an underground conduit (‘vault’) between the running rails. Conduit current collection was used in historic tram systems in Washington, Manhattan, Paris, Berlin, Marseilles, Vienna, Budapest and London. It fell into disuse because overhead wires proved much less expensive and troublesome for street railways and because in Manhattan, Paris, Washington and West Berlin, all trams were replaced by buses for reasons unrelated to the power supply issue. In Prague on the Charles Bridge (Karlův most), a system invented by František Křižík was used, similar to today's APS.

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