Malaysia's road network is one of the most comprehensive in Asia and covers a total of . The main national road network is the Malaysian Federal Roads System, which span over . Most of the federal roads in Malaysia are 2-lane roads. In town areas, federal roads may become 4-lane roads to increase traffic capacity. Nearly all federal roads are paved with tarmac except for parts of the Skudai–Pontian Highway which are paved with concrete, while parts of the Federal Highway linking Klang to Kuala Lumpur are paved with asphalt. Malaysia has over  of highways and the longest highway, the North–South Expressway, extends over  on the West Coast of Peninsular Malaysia, connecting major urban centres like Kuala Lumpur, Penang and Johor Bahru. In 2015, the government announced a RM27 billion (US$8.23 billion) Pan-Borneo Highway project to upgrade all trunk roads to dual-carriageway expressways, bringing the standard of East Malaysian highways to the same level of quality as Peninsular highways.