up to 9.6%, it is also one of the steepest and has become a popular tourist attraction. Innsbruck, which traditionally used second-hand trams from other cities, replaced its whole fleet with 32 Bombardier low-floor cars in Summer 2009. The Pöstlingbergbahn, in Linz, an unusual "mountain tramway", has a gradient of 10.6%, which makes it one of the world's steepest gradients on a surviving adhesion-only railway. The tramway now reaches the city centre via the tracks of the urban tram system. Belarus There are four tram systems in Belarus currently: Minsk, Mazyr, Novopolotsk and Vitebsk. Belgium In Belgium an extensive prewar system of tram-like local railways called Vicinal or Buurtspoorweg lines used to exist, which had a greater total route kilometre length than the main-line railway system. The only survivors of the Vicinal system are the Kusttram, the longest tram line in the world, which almost reaches France at one end of the line and the Netherlands at the other, and two short lines that form part of the Charleroi Pre-metro. Urban tram networks exist in Antwerp, Ghent and Brussels, and are gradually being extended. In Liège a new tram line is currently under construction. Bosnia and Herzegovina The electric tram started in Sarajevo in 1895. Several trams were badly damaged during the Bosnian war. Several European countries donated out of use trams to Sarajevo in the years after the war. Recently, more modern vehicles have arrived to upgrade and expand the fleet. Bulgaria Sofia is the only city that currently has a tram system. It had its first horse-drawn tram in operation in 1898. On 1 January 1901 the electric tram system was inaugurated and had 25 cars and 10 carriages and the total length of the lines was 25 km. Currently Sofia's extensive tram network consists of 15 routes, 3 of which are operated on the standard gauge of 1435mm, while the others use a narrow gauge of 1009mm. Due to the construction of the Sofia Metro there were some closures and retracing, but the system continues to be one of the largest in Europe. According to the official website, as of 2006 there are 308 km of track, with 190 trams in service on any given weekday. Croatia Zagreb has had a tram service since 5 September 1891; it is now an extensive tram network with 15 day lines and 4 night lines covering over 116 km (72