In spite of Norway's difficult terrain, the road system has been well engineered, with tunnels and zigzags, particularly in the fjordlands of the west; but there are problems of maintenance because of heavy rain in the west and freezing in the east. Road transport accounts for nearly 90% of inland passenger transport. As of 2002, the total length of highway was 91,180 km (56,659 mi), of which 67,838 km (42,154 mi) were paved, including 109 km (68 mi) of expressways. As of 2000, there were 1,851,929 passenger cars and 445,726 commercial vehicles. The state railway operates bus routes and has been steadily increasing its activities in this field, which is heavily subsidized by the government. In 2002, 4,006 km (2,489 mi) of rail line was
operational, of which 2,471 km (1,535 mi) were electrified; most of the track is standard gauge.
With a merchant fleet of 746 vessels (20,691,266 GRT) as of 2002, Norway possessed one of the world's largest fleets. The sale of Norwegian ships and their registration abroad, which increased considerably during the mid-1980s, severely reduced the size of the fleet. In 1988, the Norwegian International Ship Register program began, whereby ships could be registered offshore, thus allowing foreign vessels to operate under the Norwegian flag while reducing costs to shipowners. Oslo and Bergen have excellent harbor facilities, but several other ports are almost as fully equipped.
Norway had 102 airports in 2001, 66 with paved runways. Flesland at Bergen, Sola at Stavanger, and Fornebu and Gardermoen at Oslo are the main centers of air traffic. External services are operated by the Scandinavian Airlines System (SAS), which is 21% Norwegian-owned. Braathens Air Transport operates most of the domestic scheduled flights. Important internal air services include that linking Kirkenes, Tromsø, and Bodø; 2,000 km (1,240 mi) long, this air route is reputed to be the most difficult to operate in western Europe. In 2001, 14,558,800 passengers were carried on scheduled domestic and international flights.