Transport in Belgium is facilitated with well-developed road, air, rail and water networks. The rail network has 2,950 km (1,830 mi) of electrified tracks. There are 118,414 km (73,579 mi) of roads, among which there are 1,747 km (1,086 mi) of motorways, 13,892 km (8,632 mi) of main roads and 102,775 km (63,861 mi) of other paved roads. There is also a well-developed urban rail network in Brussels, Antwerp and Charleroi. The ports of Antwerp and Bruges-Zeebrugge are two of the biggest seaports in Europe. Brussels Airport is Belgium's biggest airport.
Rail transport in Belgium was historically managed by the National Railway Company of Belgium, known as SNCB in French and NMBS in Dutch. In 2005, the public company was split into 2 companies: Infrabel, which manages the rail network and SNCB/NMBS itself, which manages the freight and passenger services. Both companies are held by a third company, named SNCB/NMBS Holding. There is a total of 3,536 kilometres (2,197 mi), (2,563 km (1,593 mi) double track (as of 1998)), of which 2,950 km (1,833 mi) are electrified, mainly at 3,000 volts DC but with 351 km (218 mi) at 25 kV 50 Hz AC (2004) and all on standard gauge of 1,435 mm (4 ft 8 1⁄2 in). In 2004 the National Railway Company of Belgium, carried 178.4 million passengers a total of 8,676 million passenger-kilometres. Due to the high population density, operations are relatively profitable, so tickets are cheap and the frequency of services is high. The SNCB/NMBS is continually updating its rolling stock.
The network currently includes four high speed lines, three operating up to 300 km/h (186 mph), and one up to 260 km/h (162 mph). HSL 1 runs from just south of Brussels to the French border, where it continues to Lille, and from there to Paris or London. HSL 2 runs from Leuven to Liège. HSL 3 continues this route from Liège to the German border near Aachen. HSL 4 runs from Antwerp to Rotterdam by meeting HSL-Zuid at the border with Netherlands.