Hanoi is served by Noi Bai International Airport, located in the Soc Son District, approximately 15 km (9 mi) north of Hanoi. In addition, a new highway and the new Nhat Tan cable-stay bridge connecting the airport and the city center opened at the same time, offering much more convenient than the old road (via Thang Long bridge). Taxis are plentiful and usually have meters, although it is also common to agree on the trip price before taking a taxi from the airport to the city centre. That said, the main means of transport within Hanoi city are motorbikes, buses, taxis, and a rising number of cars. In recent decades, motorbikes have overtaken bicycles as the main form of transportation. Cars however are probably the most notable change in the past five years as many Vietnamese people purchase the vehicles for the first time. The increased number of cars are the main cause gridlock as roads and infrastructure in the older parts of Hanoi were not designed to accommodate them.