1992. Several other UK cities followed with their own modern tram systems, including Sheffield (Supertram, opened 1994), Birmingham and Wolverhampton (West Midlands Metro, opened 1999), London (Tramlink, opened 2000, albeit in a small part of Greater London), Nottingham (Nottingham Express Transit, opened 2004) and Edinburgh (Edinburgh Trams, opened 2014). Cardiff is currently building a system of 4 Light Rail Lines due to open in 2024. Many of these cities are planning or building network extensions. Paris reintroduced trams with line T1 in 1992, and many French cities have seen a similar revival, for example the Tramway de Grenoble and the Montpellier trams. The Czech capital Prague had planned one new line and the extension of eight others between 2007 and 2016, with an official of the Prague Public Transport Company stating that "In Europe in the past 10 years, tram transportation is the preferred way of transit; we can say that tram transportation is going through its renaissance period". In Luxembourg City, Luxembourg, trams were reintroduced in December 2017, after being replaced by buses in 1964. All the former communist countries of Central and Eastern Europe, excluding Lithuania, Northern Macedonia, Montenegro, Moldova and Slovenia, have extensive tram infrastructure. Industrial freight use of city tram lines was a widespread practice until the 1960s but has since mostly disappeared. Another factor is an increasing replacement of trams with trolleybuses as cities face a rapid increase in traffic, and such replacement often allows more of the roadway to be used by cars. One of the exceptions is Warsaw, Poland, where the last trolleybus line was closed in the year 1995 due to high maintenance costs, and replaced with buses. Czech ČKD Tatra and the Hungarian Ganz factories were notable manufacturers of trams. Austria In Austria, Gmunden, Graz, Innsbruck, Linz and Vienna all have tramway systems. With 173.4 km of track, Vienna's network is one of the largest in the world. The cars have been constantly modernised over the years and many are now ultra low-floored. Many of the Austrian tramlines have been in constant operation since they were first opened. Vienna started with horse trams in 1865 and electrification followed in 1897. Graz had horse trams in 1878 and electric cars in 1898 while Linz goes back to 1880 with electrification in 1897. The Gmunden Tramway, only 2.3 km long, is currently one of the shortest in the world, and with gradients of