foot. China had not developed the road during those years. The stretch has several sinking zones and parts are prone to landslides. The flow of vehicles is regulated and road maintenance is supported by the Border Roads Organisation, a wing of the Indian Army. The road has an average rise of per km over a stretch of . Around 2006, plans were made to widen the road. Double-laning commenced in 2008. Also known as the JN Marg, and later known as National Highway (NH) 310, an alternative axis was constructed in 2020. 2006 also marked the inauguration of a railroad from Beijing to Lhasa via the Qinghai–Tibet line. In 2011, the railroad began to be extended to Shigatse. There has been talk of extending the Qinghai-Tibet Railway to Yadong. China National Highway 318 (Shanghai to Zhangmu) is connected to Chumbi Valley from Shigatse via provincial road S204, about 30 km from Nathu La and Jelep La. India had been planning an extension of rail services from Sevoke in West Bengal's Darjeeling district to Sikkim's capital Gangtok, from Nathu La. However the broad gauge line has been shortened to a 45 km extension to Rangpo, due for completion in 2022. Notes References Bibliography — — — Further reading Books Journals Think tanks News External links Mountain passes of Sikkim Mountain passes of Tibet Mountain passes of China Mountain passes of India China–India border crossings Mountain passes of the Himalayas Yadong County Gangtok district Tourism in Northeast India