Sakha lies north of the important Trans-Siberian railway and Trans-Siberian Highway. Thus there is some distance between the republic and the main travelling routes across the country. The main road link in Sakha is the Lena Highway towards the south or the Kolyma Highway towards the east. The roads can generally be passed all year round, except across the Lena River where there is no bridge. Therefore, cars have to take a ferry across the river during summer or drive on the ice in winter. The Amur-Yakutsk train line connects Sakha with the rest of the Trans-Siberian railway. The republic has several airports, including the Yakutsk International Airport. Flights from these airports link Sakha to cities further away. The usage of the Northern Sea Route to transport goods is also possible at certain times of the year.