Alternative Tunnel System for a 8.5Km Long Road Tunnel Through the Himalayas

ALTERNATIVE TUNNEL SYSTEM FOR A 8.5KM LONG ROAD TUNNEL THROUGH THE HIMALAYAS

Florian KRENN, Geoconsult India Pvt.Ltd. ; Singapore. 21st of November 2019 www.geoconsult.com Table of Contents

• Introduction • DPR – Proposed Tunnel System • Mont Blanc Tunnel – system and short discussion of Fire 1999 • Possible Alternative Solutions • Alternative 1 – Main tunnel & escape tunnel • Alternative 2 – Two traffic tubes • Conclusion / Results

2 www.geoconsult.com Introduction

• In 2009 / 2010 National Highway Authority of India tendered a number of packages on the Jammu – Srinagar Highway, then NH-1A, for four-laning (major tunnels – two lane) • Two packages contained long tunnels, 9km and 8.5km respectively • The 8.5km long tunnel from Qazigund to Banihal is part of Package II, which Navayuga Engineering Company (NEC) won and is executing • The original project foresaw a single tube arrangement, which was lateron changed

www.geoconsult.com Overview

www.geoconsult.com The NH 1A / existing pass road

www.geoconsult.com New Banihal – Qazigund Tunnel

As per DPR – Original Design • 8.5km long • Single tube, ventilation duct in the invert • Bidirectional traffic • Alignment approximately parallel to the then under construction Pir Panjal Rail Tunnel (T80), completed 2013

www.geoconsult.com Alignment – showing the expected strata

www.geoconsult.com DPR – Proposed Tunnel System

Fresh Fresh Fresh Smoke Air Air Air Extraction

www.geoconsult.com8 Mont Blanc Tunnel – System

• Built in the sixties, adapted in 1999-2001 • No other long alpine tunnel has that system • No separate escape route • Evacuation of elderly and handicapped people to shelter area difficult and time consuming • Very good rock mass, allowed for large single cross section • Only access for emergency services via normal traffic lanes

www.geoconsult.com9 Shortcomings of the original solution

• Escape route is not a construction separated from the area where the incidents might occur (is not according to European Guideline 2004/54/EC – Minimum Safety Requirements for Tunnels) • Any damage which requires repairs of the tunnel causes impediments / full blockage of this strategic route • duct system below the pavement cannot be controlled 100% (terrorism) • any leakage of liquids like gasoline through the pavement slab (cracks, joints) into the air ducts leads to the development of combustible gases / air-liquid mixtures which increase the danger of explosions in the “safe” area

10 www.geoconsult.com Alternative Solution 1

Exhaust Air Duct • Twin lane Main Tunnel Fresh Air Duct • (Bi directional traffic) • With separate Escape Tunnel ~17m² ~17m² • (Lay By Niches are required every 1000m)

Connected through • Vehicular cross passages every Excavation area: 41 m² 1500m (with invert arch) • Pedestrian cross passages every Excavation area: 151 m² (with invert arch) 500m

www.geoconsult.com Alternative Solution 2

• Two single lane Tunnels Air Duct Driving Lane Air Duct • (unidirectional traffic)

~17m² ~17m² • (Lay By Niches are not

Driving Emergency required) Lane Lane ~45m² Connected through • Vehicular cross passages every 1500m

Excavation area: each tube 99 m² (with invert arch) • Pedestrian cross passages every 500m

www.geoconsult.com Incident Ventilation in case of Fire - 1

• Jet Fans direct the flow of air to the extraction point • Direct extraction of smoke at the extraction point

~17 ~17 Air Duct ~17m m² m²Fresh ² Exhaust Air Duct Air Duct

120 m3/sec 120 m3/sec

Emergency Lane

13 www.geoconsult.com Incident Ventilation in case of Fire - 2

➢ Jet Fans direct the flow of air to the extraction point, requiring reversible axial fans ➢ Air velocity shall be 2m/s towards extraction point ➢ Direct extraction of smoke at the extraction point (120m3/sec) ➢ Only the extraction points near the incident are open (max. 3pcs, distance between extraction points approx. 100m) ➢ All other extraction points are closed for maximum efficiency of extraction 14 www.geoconsult.com Alternative 1 - Cross Section of the System

~17m² ~17m²

Exhaust Fresh Air Air Duct Duct

15 www.geoconsult.com Alternative 1 - Cross Section with Lay By

Exhaust Fresh Air Air Duct Duct

www.geoconsult.com Alternative 1 - Full transverse Ventilation Fully transverse ventilation • Needs to run throughout FRESH AIR WASTE AIR • Needs proper adjustment of the inlets • Since no shafts were available, ventilation sections would be >4000m

17 www.geoconsult.com Alternative 1 – Accident Scenario

Traffic Accident

18 Service tunnel must be dimensioned for ambulance vehicles www.geoconsult.com Alternative 2 - Cross Section / System

Emergency Emergency Lane Lane

19 www.geoconsult.com Alternative 2 – Accident Scenario

Traffic Accident

20 www.geoconsult.com Alternative 2 - Operation under maintenance

Tunnel under maintenance

➢Alternating Flow of Traffic through intact tube ➢Area of maintenance not affected

Tunnel under maintenance

21 www.geoconsult.com Longitudinal Ventilation Only

Concentration of Exhaust Fumes along one tube 120%

100%

80%

60% Jet Fans in the 40% tunnel Concentration 20% Threshold Value Emergency 0% Lane 0% 20% 40% 60% 80% 100% Percent of Total Tunnel Length

Jet Fans support the flow of air in the direction of the traffic (piston effect supports further)

22 www.geoconsult.com Longitudinal Ventilation with support – Mode 1 Concentration of Exhaust Fumes along one tube 140% 120% 100% 80% Concentration w/o support Concentration with support FRESH AIR 60% 40% 20% 0% 0% 20% 40% 60% 80% 100% Percent of Total Tunnel Length

Emergency Lane

➢ Jet Fans support the flow of air in the direction of the traffic ➢ fresh air is blown in at the middle of the tunnel

23 www.geoconsult.com Longitudinal Ventilation with support – Mode 2

Concentration of Exhaust Fumes along one tube 200% Concentration w/o support 150% Concentration with support 2 Threshold Value 100%

50%

0% 0% 10% 20% 30% 40%Percent of Total50% Tunnel Length60% 70% 80% 90% 100%

10m/sec

➢ Jet Fans support the flow of air in the direction of the traffic ➢ waste air is sucked out before the middle of the tunnel ➢ fresh air is blown in after the middle of the tunnel 24 www.geoconsult.com Comparison of All Solutions

Feature DPR solution Main Tunnel & Escape Twin Tube Solution Tunnel Separate Escape Route NO YES YES Access to Incident through separate route NO YES (geometric YES restrictions)

Traffic in operation bidirectional bidirectional unidirectional Traffic during large maintenance possible NO NO YES (one tube)

25 www.geoconsult.com Criteria to Choose Alternative 2

• Unidirectional traffic – increased road safety • One full spare tube – maintenance flexibility • Ventilation system

www.geoconsult.com Result

• The Contractor (who was in favour of the Alternative 2) presented the matter to the Client • The Client agreed finally • Alternative 2 has been designed and is being executed