Desh Ratan Gupta, the chief engineer in-charge of construction and survey for Northern Railways , explains why the Bilaspur-Manali-Leh route will by far be more challenging than the Udhampur-Baramulla project in Kashmir, a part of which is operational now. In a chat with ET, Gupta says the project will serve two purposes: one for the defence sector and the other to meet the needs of ordinary citizens. Excerpts:The Bilaspur-Manali- Leh route is about 650 km by road. The Manali-Leh route is closed for almost five months a year, making it difficult for people as well as defence personnel. That’s why the Government of India decided to have rail connectivity up to Leh. For this, the Northern Railways is undertaking the final location survey. It’s a detailed study to know the entire area of interest — how challenging the terrain and geology is; whether the railway line can be laid; will it be feasible at all at the required gradients, etc. Bilaspur to Kullu (short of Manali) would be relatively less difficult; there we have to avoid hot springs in Manikaran area (in Kullu in Himachal Pradesh). Between Manali and Leh, about 300 of 470 km are covered in snow for most of the time. The line passes through four mountain passes ranging from 3,976 m to 5,360 m (13,000 ft to 17,500 ft), and each pass will have unique challenges, the most challenging being Taglang La at over 5,300 m (17,480 ft). Also, the temperature variation from minus 30 degree Celsius to plus 30 degree Celsius is a big challenge.Then, there are avalanche-prone areas on the way. The proposed line falls in Seismic Zones 4 and 5 shall pass through a number of tectonic faults and thrust zones. In fact, 11% of our proposed track falls in Zone 5 (the most vulnerable for earthquakes). We must also keep in mind the habitats. Despite the difficulties, we must connect to the villages. In this alignment, we start with 500 m elevation in Bilaspur to about 3,215 m in Leh, and it crosses passes at over 5,000 m. The railways, unlike the roads, can’t have sharp curves and steep gradients. So, a large portion of the track — maybe 60-65% — will pass through tunnels. In this survey, we are doing multi-criteria analysis such as constructibility, maintainability, accessibility, economy, safety, connectivity, geological and hydrological assessment, bridge and tunnel length assessment, etc.The survey (which began in September 2016) will take about three years. There will be three phases. We will soon complete Phase I in which we will have a few alternative corridors in various gradients — 1:40, 1:60 and 1:80 (a gradient of 1:40 means that every 40 m, the track will be elevated by 1 m, i.e. for every 1 km, track will be risen by 25 m). The ideal situation is to have sharper gradients, which will mean a shorter route and less cost. But we have to weigh in the operating requirements i.e. hauling capacity and speed of trains. So, there will be a trade-off between sharper gradients and the hauling capacity.Our study indicates that the gradient will be 1:40 or 1:60, or a mix of both. DPR (detailed project report) is expected to be ready in 2019. The construction will begin only after the DPR is approved by the government and the project is sanctioned. The government will then take the final call on how to proceed.The Bilaspur-Leh project is the most challenging for the Indian Railways. Between Bilaspur and Leh, there are four Himalayan ranges unlike just one (Pir Panjal) in Udhampur project. The highest point the Udhampur-Baramulla line passes through is only 1,750 m. Here, the line has to pass areas at over 5,300 m. Sub-zero conditions of this magnitude (minus 30 degree Celsius in some areas) do not exist in Udhampur-Baramulla project. Here, there are many avalanche-prone patches too.Along the route, the defence has many establishments. They will have specific requirements. But it will also serve the people who will get all-weather connectivity. Now, essential commodities are brought by air during winter. With the line in place, prices will come down. It will serve two purposes: strategic as well as the welfare of the people. Another spin-off will be tourism in Ladakh It’s too early to talk about cost. By the end of next year, we will have a tentative idea. The actual cost will be known only after the DPR is ready (by 2019).