Heavy snowfall on the highest passes can block traffic, cutting Leh from Srinagar for some six months each year. During springtime, the Border Roads Organisation plows snow and repairs damages caused by landslides. Zoji La pass received reportedly some of snowfall in 2008.
Geography
For most part, NH 1D transited through extremely treacherous terrain and followed the historic trade route along the Indus River, thus giving modern travelers a glimpse of villages which are historically and culturally important. The road generally remained open for traffic from early June to mid-November. The total length of NH 1 was. The two highest passes on NH 1D include Fotu La at elevation and Zoji La at elevation. Between Fotu La pass and Leh, a government checkpoint is stationed in the village of Khalatse. Dras, located some from Srinagar at elevation of, is the first major village over the Zoji La pass. The village is inhabited by a population of mixed Kashmiri and Dard origins, having a reputation of being the second coldest permanent inhabited spot in the world after Siberia, with temperatures dropping to.
History
In the 17th and 18th centuries, the road was only a track, impassable even with ponies. Goods, mainly pashmina wool, were carried by porters from Yarkand and Tibet for Kashmir shawl industry. In the 19th century, the route was improved, allowing pony caravans to pass. This work was started after DograGeneral Zorawar Singh conquered Ladakh region from the Sikh Empire during 1836–1840 Trans-Himalayan campaign and princely state of Jammu and Kashmir was formed when the British sold Kashmir to maharaja Gulab Singh in 1846 Treaty of Amritsar. In April 1873, the Kashmir government allocated 2,500 rupees annually for upkeep of the Treaty Road and associated serais. During the 1950s, tensions rose in Ladakh region. China secretly built a military road spanning some from Xinjiang to western Tibet, which was discovered by Indian in 1957 and confirmed by Chinese maps showing the road in 1958. The political situation eroded, culminating in 1962 in the Sino-Indian War. The road on the Chinese side gave PLA an advantage as a reliable supply line, giving the Indian Army impetus to build a road for supply and mobilisation of their own troops. The building started from Sringar in 1962, reaching Kargil in two years. This was the basis of modern Srinagar-Leh Highway. Building the road was hazardous task, given the challenging geographical location, and maintaining the road is still an unenviable task. Restrictions on civilian traffic were lifted in 1974. This highway was used as mobilisation route by the Indian Army during Pakistani occupation of Kargilin 1999, known as Operation Vijay.