UKPSC Prelims 2025 General Studies Paper-I · Question 51 of 149

Correct — C, 4.531 km.

The Silkyara Bend–Barkot tunnel is driven through a ridge on the Dharasu–Yamunotri stretch of National Highway 134, in Uttarkashi district. The length carried in its February 2018 CCEA sanction is 4.531 km.

The stem says "between Gangotri and Yamunotri". The record puts the saving of about 20 km between Dharasu and Yamunotri — and Dharasu is the junction where NH 134 leaves NH 34, the Gangotri road.

The paper is measuring from that junction, which is why its phrasing reads loosely.

Notice what the option set is doing. Every figure ends in .531, so the decimal tail carries no information at all. The whole-kilometre digit is the only thing on trial here.

Hold the project as a bore of about four and a half kilometres that saves about twenty kilometres of road.

Those are two separate quantities, and this item asks only for the first.

• (a)
  2.531 km — 2.531 km sits two kilometres short of the figure on record. The length carried in the February 2018 CCEA approval is 4.531 km.

  The .531 tail is printed on every choice in the set, so it settles nothing.

• (b)
  3.531 km — 3.531 km falls one kilometre short of the figure on record, and a kilometre is a heavy error on a bore of this size.

  It is the nearest wrong value to the key, separated from it only by the whole-kilometre digit. The digit to fix in memory is four.

• (d)
  6.531 km — 6.531 km runs two kilometres longer than the figure on record for the Silkyara bore.

  A number this size belongs to a bigger class of Himalayan highway tunnel. The Atal Tunnel at Rohtang, in Himachal Pradesh, is about 9 km — roughly twice Silkyara — and carrying that scale across inflates the answer.

A road tunnel through a Himalayan spur exists to replace a long looping climb over or around the ridge with a short, near-level bore. The saving then shows up twice: in kilometres of road and in driving time.

So two numbers travel with any such project, and they are not the same number — the length of the tunnel itself, and the distance the route saves once the tunnel opens.

• The Silkyara Bend–Barkot tunnel is 4.531 km long, two-lane and bi-directional, with an escape passage alongside.
• It lies in Uttarkashi district, Uttarakhand, on National Highway 134, which runs from Dharasu north to Yamunotri.
• The Cabinet Committee on Economic Affairs approved the tunnel in February 2018.
• Published figures put the tunnel at Rs 1,119.69 crore within a total project cost of Rs 1,383.78 crore.
• It is expected to cut about 20 km off the Dharasu–Yamunotri road and about an hour of travel time.
• The tunnel is part of the Char Dham road programme covering the approaches to Yamunotri, Gangotri, Kedarnath and Badrinath.
• A section collapsed on 12 November 2023; the 41 trapped workers were brought out on 28 November 2023.
• The rescue used horizontal auger drilling and then manual rat-hole mining through the last stretch of debris.
• NHIDCL is the implementing agency; Navayuga Engineering Construction Limited was the construction contractor.

• All four printed figures end in .531, so recognising the decimal confirms nothing; the whole-kilometre digit is the entire question.
• The bore length and the road distance the tunnel saves are separate quantities, and only the bore length is asked for here.
• Importing the scale of another Himalayan tunnel — the Atal Tunnel at Rohtang is about 9 km — pushes the answer up into the longer options.
• The tunnel is driven on the Dharasu–Yamunotri arm, National Highway 134, not along the Gangotri road itself; the stem's Gangotri-to-Yamunotri wording counts from Dharasu, the junction where NH 134 leaves NH 34.
• The February 2018 sanction, the 2023 collapse and the eventual completion are different dates and are easy to fuse into one.

• practice — not a real PYQ

  The Silkyara Bend–Barkot tunnel, on the Dharasu–Yamunotri highway, lies in which district of Uttarakhand?

  • (a)Chamoli
  • (b)Tehri Garhwal
  • (c)Uttarkashi
  • (d)Rudraprayag
  Answerc — Uttarkashi. Both the Silkyara portal and Dharasu are in Uttarkashi district, which also holds the Yamunotri and Gangotri shrines.

  Chamoli is the district of Badrinath and Joshimath; Rudraprayag carries the Kedarnath approach and the Alaknanda–Mandakini confluence; Tehri Garhwal is the district of the Tehri dam on the Bhagirathi.

• practice — not a real PYQ

  In November 2023, forty-one workers were trapped in a collapsed under-construction highway tunnel and were later brought out safely. That tunnel is in which State or Union Territory?

  • (a)Himachal Pradesh
  • (b)Uttarakhand
  • (c)Jammu and Kashmir
  • (d)Arunachal Pradesh
  Answerb — Uttarakhand. The collapse was at the Silkyara Bend–Barkot tunnel in Uttarkashi district on 12 November 2023, and the workers came out on 28 November 2023.

  Himachal Pradesh is where the Atal Tunnel at Rohtang runs; Jammu and Kashmir carries the Chenani–Nashri tunnel on the Jammu–Srinagar highway; Arunachal Pradesh has the Sela tunnel on the road towards Tawang.

• practice — not a real PYQ

  The Silkyara Bend–Barkot tunnel is being driven on National Highway 134, which leaves the main route at Dharasu. Which shrine does that highway lead to?

  • (a)Gangotri
  • (b)Yamunotri
  • (c)Kedarnath
  • (d)Badrinath
  Answerb — Yamunotri. NH 134 is the spur that runs north from Dharasu to Yamunotri, and the tunnel sits on that stretch.

  Gangotri is reached by continuing up the Bhagirathi valley past Uttarkashi rather than by this spur; Kedarnath is approached through Rudraprayag and Gaurikund; Badrinath lies far to the east along the Alaknanda in Chamoli district.