Also in the 1880s, third-rail systems began to be used in public urban transport. Trams were first to benefit from it: they used conductors in conduit below the road surface (see Conduit current collection), usually on selected parts of the networks. This was first tried in Cleveland (1884) and in Denver (1885) and later spread to many big tram networks (e.g. New York, Chicago, Washington DC, London, Paris, all of which are closed) and Berlin (the third rail system in the city was abandoned in the first years of the 20th century after heavy snowfall.) The system was tried in the beachside resort of Blackpool, UK but was soon abandoned as sand and saltwater was found to enter the conduit and cause breakdowns, and there was a problem with voltage drop. Some sections of tramway track still have the slot rails visible.