Babusar Tunnel

General Overview

The National Highway Authority (NHA) of Pakistan intends to provide an all-weather alternate road to Chillas & onwards to Northern Areas of Pakistan through Naran Valley by constructing a tunnel at Babusar Pass along with the provision of Avalanche Galleries. Presently, the existing road between Naran and Chillas is interrupted with high altitude mountains culminating at an altitude of 4,147 meters or 13,700 ft. at Babusar Pass and remains snow-covered for about 6 months, normally from November to April. The existing road also has geometric issues, including 36 hairpin bends & steep grades between Babusar & Chillas.

The project involves the construction of an approximately 12 km tunnel at Babusar Pass and an approximately 80-100 km long all-weather route between Naran & Chillas along with the provision of Avalanche Galleries and Snow Shelters. The area is among the most visited tourist destinations (about 700,000 vehicles in peak season). The route is also about 90 km shorter than KKH from Mansehra to Chillas and serves as an alternate route to the Pak-China road connection. The length and travel time will further reduce with the provision of the tunnel at Babusar and the creation of an all-weather facility. About 15,000 vehicles/day will benefit.

Tunnel Salient Features & Standards

  • Length: Approximately 12 km
  • Lanes: 2
  • Lane width: 3.65 meters
  • Shoulder width: To be determined after detailed Feasibility Report.
  • Terrain: To be determined after detailed Feasibility Report.

Major Cities/Towns

  • Babusar
  • Naran
  • Jalkhad
  • Chillas

Tunnel Safety Standards

  • Directive 2004/54/EC of The European Parliament and of the Council on Minimum Safety Requirements for Tunnels in the Trans-European Road Network, 2004.
  • Systems and Equipment for Fire and Smoke Control in Road Tunnels, World Road Association (PIARC) Committee on Road Tunnels Operation (C3.3), Report 2007.
  • Road Tunnels: Vehicle Emissions and Air Demand for Ventilation, World Road Association (PIARC) Technical Committee C4 Road Tunnel Operation, Report 2012.
  • Human Factors and Road Tunnel Safety regarding Users, World Road Association (PIARC), Report, 2008.
  • Road Safety in Tunnels, World Road Association (PIARC), Report 05.04.B, 1995.
  • Guide for the lighting of Road Tunnels and underpasses (International Commission of Illumination, CIE 88: 2004), Austria.

Design Standards and Criteria for Highway and Structures

Description

  • Level Terrain

  • Design Speed (kph): 120
    • Lane Width (m): 3.65
    • No. of Lanes: 6
    • Paved Shoulder
      • Outer (m): 3
      • Inner (m): 1
    • Carriageway Cross Slope
      • Pavement: 2%
      • Shoulder
        • Outer shoulder: 4%
        • Inner shoulder: 2%
    • Horizontal Alignment
      • Minimum radius (m): 755
      • Maximum super elevation: 6%
    • Vertical Alignment
      • Maximum Gradient: 3%
      • Minimum Gradient: 0.3%
    • Minimum Clearance
      • Vertical Clearance
        • Underpass (m): 5.1
        • Subway(m): 4.5
        • Flyover (m): 5.5
        • Over Railway line (m): 6.5

  • Rolling Terrain

    • Design Speed (kph): 100
    • Lane Width (m): 3.65
    • No. of Lanes: 6
    • Paved Shoulder
      • Outer (m): 3
      • Inner (m): 1
    • Carriageway Cross Slope
      • Pavement: 2%
      • Shoulder
        • Outer shoulder: 4%
        • Inner shoulder: 2%
    • Horizontal Alignment
      • Minimum radius (m): 435
      • Maximum super elevation: 6%
    • Vertical Alignment
      • Maximum Gradient: 4%
      • Minimum Gradient: 0.3%
    • Minimum Clearance
      • Vertical Clearance
        • Underpass (m): 5.1
        • Subway(m): 4.5
        • Flyover (m): 5.5
        • Over Railway line (m): 6.5

  • Mountainous Terrain

    • Design Speed (kph): 80
    • Lane Width (m): 3.65
    • No. of Lanes: 6
    • Paved Shoulder
      • Outer (m): 2.5
      • Inner (m): 1
    • Carriageway Cross Slope
      • Pavement: 2%
      • Shoulder
        • Outer shoulder: 4%
        • Inner shoulder: 2%
    • Horizontal Alignment
      • Minimum radius (m): 250
      • Maximum super elevation: 6%
    • Vertical Alignment
      • Maximum Gradient: 6%
      • Minimum Gradient: 0.3%
    • Minimum Clearance
      • Vertical Clearance
        • Underpass (m): 5.1
        • Subway(m): 4.5
        • Flyover (m): 5.5
        • Over Railway line (m): 6.5

Following Codes to be followed

  • For Geometric and Pavement Design:
    • AASHTO – American Association of State Highway and Transportation Officials.
    • British Road Note 31 (Latest edition) for pavement design.
  • For Materials and Testing:
    • ASTM – American Society for Testing & Materials.
    • AASHTO – American Association of State Highway and Transportation Officials.
  • For Structures: following codes and standards will be followed for structural designing.
    • Vehicles Live Load
      • West Pakistan Code of Practice for Highway Bridges 11067 (WPCHB) specifies more severe loads to be considered in combination with other loads such as dead load etc, as follows:
        • Tank loading: The 70-Ton tracked military vehicle to be placed in accordance with WPCHB to give maximum stresses.
        • Class A loading: The 54.5 Ton train of trailers (with different axle loads) to be placed in accordance with WPCHB to give maximum stresses.
        • Check Deck Slab for Punching Shear: Additionally, the bridge deck slab shall be checked in Punching Shear for a Wheel Load of 21,000 Pounds [105 KN] on 0.3 x 0.6 m² tire contact area.
  • Design Criteria/Standards
    • For Structural Design: AASHTO LRFD Current Edition
    • For Structural Loads: All Loads will be as per current AASHTO LRFD, except the following which shall be according to West Pakistan Code of Practice for Highway Bridges 11067
      • Class AA 70 ton tank and Impact and Braking associated with it
      • Axle Load and spacing of Class A truck train only
      • Additionally, the bridge deck slab shall be checked in punching shear for a wheel load of 21000 pounds (105KN) on 3X0.6m² tire contact area
    • For Seismic Analysis: AASHTO LRFD current Edition but for selecting PGA latest seismic zoning map for Pakistan shall be followed

Tunnel Design

  • New Austrian Tunnel method (NATM) will be used for construction of Tunnels. However, the use of shield and tunnel boring machines (TBM) will be encouraged.
  • The use of flexible primary lining in the shape of Shotcrete, wire mesh, rock bolt lattice girders will be ensured.
  • In case of weaker rock mass, the use of pipe for pole/pipe roofing to be rested from crown support to ensure safety during execution.
  • Two separate tunnels with each tunnel having two lanes with a service tunnel in between will be provided.
    • Width of each lane: 3.65 meters
    • Total width of each tunnel: 9 meters
    • Overhead clearance: 7 meters
    • Proper sidewalks/curbs will be provided
  • Proper tunnel ventilation, lighting, water supply for fire fighting, CCTV cameras, emergency telephone, monitoring equipment of emissions and visibility along with emergency illuminated sign posting will be provided in the tunnel

Hydrology Study

The existing road traverses along the banks of River Kunhar and encounters a number of nullahs and natural watercourses emanating from mountain tops. The designing of the highway and its structures will require special consideration and will warrant special hydrological studies before finalizing the final detailed design. The design return period for designing shall be considered hundred (100) years for bridges and fifty (50) years for the culverts.

ABUSAR TUNNEL ON N-15

NATIONAL HIGHWAY AUTHORITY

NHA HQ, 27, Mauve Area, G-9/1, Islamabad

UAN: 111-000-642

Web: www.nha.gov.pk

Email: info@nha.gov.pk