Out of the four railway lines, three are in the northeast and one in northern India, Minister of State for Railways Manoj Sinha told the Rajya Sabha.
"The ministry of defence has identified four strategic lines along the India-China border," Sinha said in a written reply.
The four lines identified are Missamari in Assam to Tawang in Arunachal Pradesh via Tenga (378 km); Pasighat in Arunachal Pradesh to Rupai in Assam via Tezu (227 km); North Lakhimpur in Assam to Silapathar via Bame in Along district of Arunachal Pradesh (249 km); and Bilaspur in Himachal Pradesh to Leh in Jammu and Kashmir via Manali (498 km).
"The railways ministry has requested the ministry of defence to convey approval to carry out final location survey at a cost of Rs.345 crore (Rs.3.45 billion) and provide the necessary funds," Sinha said.
According to the minister, none of these projects has so far been sanctioned.
"The time of completion and cost cannot be ascertained till completion of the final location survey and detailed geo-technical studies, as all these projects pass through very difficult terrains of the young Himalayas," he said.