bus lines (Schnellbus, SB) 18 semi-fast bus lines (CityExpress, CE) 6 trolleybus lines (in Solingen) 15,300 km of route network (bus, light rail, and train) 11,500 transit stops In 2022 the VRS and AVV area contains in regional rail transit 7 S-Bahn lines (with 4 being part of the Rhein-Ruhr S-Bahn) 11 RegionalExpress lines (6 conntected to VRR) 18 RegionalBahn services in local rail transit 16 Stadtbahn lines (see: Cologne Stadtbahn and Bonn Stadtbahn) 3 streetcar (Straßenbahn) lines within the city of Bonn Road North Rhine-Westphalia has the densest network of Autobahns in Germany and similar Schnellstraßen (expressways). The Autobahn network is built in a grid network, with five east–west (A2, A4, A40, A42, A44) and eight north–south (A1, A3, A43, A45, A52, A57, A59, A61) routes. The A1, A2, A3, A4 and A61 are mostly used by through traffic, while the other autobahns have a more regional function. Both the A44 and the A52 have several missing links, in various stages of planning. Some missing sections are currently in construction or planned to be constructed in the near future. Additional expressways serve as bypasses and local routes, especially around Dortmund and Bochum. Due to the density of the autobahns and expressways, Bundesstraßen are less important for intercity traffic. The first Autobahns in the Region opened during the mid-1930s. Due to the density of the network, and the number of alternative routes, traffic volumes are generally lower than other major metropolitan areas in Europe. Traffic congestion is an everyday occurrence, but far less so than in the Randstad in the Netherlands, another polycentric urban area. Most important Autobahns have six lanes. Airports The region benefits from the presence of several airport infrastructure. The main airport is Düsseldorf Airport, world class, which hosts 24.5 million passengers per year and offers flights to many destinations. Düsseldorf is the third largest airport in Germany after Frankfurt and Munich; It is a hub for Eurowings and a focus city for several more airlines. The airport has three passenger terminals and two runways and can handle wide-body aircraft up to the Airbus A380. The second airport is the international airport of Germany's fourth-largest city Cologne, and also serves Bonn, former capital of West Germany. With around 12.4 million passengers passing through it in 2017, it is the seventh-largest passenger airport in Germany and the third-largest in terms of cargo operations. By traffic units, which combines