INTERNATIONAL SEMINAR Desafío para el Diseño, Construcción ...€¦ · RABT 2006 Longitudinal with point extraction every 2 km or smoke extraction through dampers Smoke extraction

INTERNATIONAL SEMINARLONG TUNNELS

17, 18 y 19 de Octubre 2012Santiago, Chile

VENTILATION AND SECURITY IN LONG TRANSALPINEROAD TUNNELS

Dr. Ing. EPFL Uwe Drost

Desafío para el Diseño, Construcción y Operación

Challenges for Design, Construction and Operation

PIARC CHILE

PRESENTATION OUTLINE

1. Why ventilation?

2. Boundary conditions of long transalpine road tunnels

3. Sanitary ventilation

4. Emergency ventilation

5. Characteristics of some transalpine tunnels

6. Résumé

1 – WHY VENTILATION?

Gotthard-Tunnel 2001Mont Blanc 1999

Via Mala 2006Tauerntunnel 1999

Fréjus-Tunnel 2005

Tunnel Croci, 22nd of September, 2012

Typical long road tunnel fire probabilities:• Passenger car fire every 2-4 years• Truck fire, minor every year• Truck fire, major every 8 years

1 – WHY VENTILATION?

2 - TRANSALPINE ROAD TUNNELS2.1 Exemplary boundary conditions• Long tunnels, length > 6-7 km• Altitude above seal level up to 1900 m• Vertical height between heads typically 50-150 m• Difference between internal and• external temperature 15-30 K• Length of ventilation segments 2-5 km• Shaft lengths up to 850 m• Barometrical pressure differences• between heads up to +/- 900 Pa

Example:high pressure in centralEurope, low pressure in ItalyDelta-P Alps 500 Pa (5 mbar)

3 - SANITARY VENTILATION3.1 Historical trend

Very strong reduction offresh air needs over thelast two decades(factor 8-10) because of• Catalysts• Particulate filters• Optimized internal

combustion

However: A residualvisibility requirementwill always remainbecause of abrasion(wheels, road) anddust raise.

CO-emissions of a truck

Visibility impact of a truck

3 - SANITARY VENTILATION3.2 Example Pfändertunnel, 6.6 km

Existing tube, 1980

Fresh air section 10.5 m2

Traffic 6600 vehicles/day

(1982 bidirectional)

Second tube, 2012

Fresh air section 4.5 m2

Traffic 31’500 vehicles/day

(2012 bidirectional)

3 - SANITARY VENTILATION3.3 Ventilation schemes – unidirectional traffic

++ Excellent initial fire conditions+ Easy maintenance- Traffic volume limited-- Overcomes only weak dp

++ Suited for high delta-P++ Excellent initial fire conditions- Traffic volume limited

++ Suited for high delta-P++ Excellent initial fire conditions+ Allowance for high traffic vol.- High CAPEX

++ Suited for high delta-P+ Bidirectional traffic possible+ High traffic volumeo Initial fire conditions- High ventilation power-- Very high CAPEX

Full-traversal ventilation

Longitudinal with Saccardo nozzle

Longitudinal with Jet-Fans

3 - SANITARY VENTILATION3.4 Ventilation schemes – bidirectional traffic

+ Quick reaction in case of fire+ Low ventilation power- Air pollution gradient- Bad initial fire conditions

Longitudinal ventilationwith point exhaust

+ Constant air quality- High ventilation power- High CAPEX-- Bad initial fire conditions

(air velocity, reaction time)

Semi-transversesupply ventilation

Semi-transverseexhaust ventilation

Full-traversal ventilation

+ Quick reaction in case of fire- Air pollution peak in tunnel- Bad initial fire conditions-- Very high ventilation power

++ Excellent initial fire conditions+ Constant air quality- High ventilation power- High CAPEX

Full transverseventilation

4 – EMERGENCY VENTILATION4.1 Ventilation schemes

Longitudinal ventilation with jet fans (or Saccardo nozzles)

Smoke extraction through dampers

Unidirectional traffic only, without congestion risk

Unidirectional or bidirectional traffic

SMOKE EXPULSION

STRATIFICATION

4 – EMERGENCY VENTILATION4.2 Regulatory requirements (>6 km)

Country(alphabeticorder)

Configuration forlong unidirectionaltunnels

Configuration forlong bidirectionaltunnels

Design firesize

Smoke extractioncapacity (crosssection 50 m2)

AustriaRVS 09.02.31

Smoke extractionthrough dampers

Smoke extractionthrough dampers

30 MW 120 m3/s

FranceAnnex 2, 2000-63

Longitudinal with pointextraction every 5 kmor smoke extractionthrough dampers

Smoke extractionthrough dampers

30 (200) MW Point extraction:200-250 m3/sThrough dampers:120 m3/s

GermanyRABT 2006

Longitudinal with pointextraction every 2 kmor smoke extractionthrough dampers

Smoke extractionthrough dampers

30-100 MW Point extraction:225 m3/sThrough dampers:120 - 300 m3/s

ItalyANAS 2009

Smoke extractionthrough dampers

Smoke extractionthrough dampers

30-200 MW 200-250 m3/s

SwitzerlandASTRA 13 001

Smoke extractionthrough dampers

Smoke extractionthrough dampers

30 MW 165-200 m3/s

USANFPA 502

Longitudinal orextraction

Smoke extraction According tovehicles

According to designcalc’s

5 – SOME TRANSALPINE TUNNELS5.1 Overview

Road Tunnel Year Type Ventilation / velocity control

Fréjus tunnel12.9 km

1980 /2015

bidirectional,possiblyunidirectional from2015

(semi-) transverse/ longitudinal4 stationsvelocity control: supply/exhaust,second tube 75 jet fans

Mont Blanc tunnel11.6 km

1965 bidirectional (semi-) transverse/ 2 stationsvelocity control: 76 jet fans

Gotthard tunnel16.9 km

1980 /2030

bidirectional /unidirectional from2030

transverse/ 6 stationsvelocity control: supply/exhaust

Gran San Bernardo5.8 km

1964 bidirectional semi-transverse / 4 stationsvelocity control: none yet

San Bernardino6.6 km

1967 bidirectional semi-transverse / 4 stationsvelocity Control: jet fans

5 – SOME TRANSALPINE TUNNELS5.2 Gotthard Road Tunnel – Outline

5 – SOME TRANSALPINE TUNNELS5.3 Gotthard Road Tunnel – Main Data

• Single bore, bidirectional traffic• Length 16.9 km• Slope +1.40% / -0.30%

(delta height heads 66 m)• Traffic space cross section 40/42 m2• Safety exits 73 (every 250 m)• Daily traffic volume 17’000 vehicles ( 15% trucks)• Ventilation system Full transverse, 23 axial fans

(up to 2.9 MW)• Ventilation stations total 6, thereof 4 underground• Dampers 178 (every 96 m)• Air velocity control PID controlled air supply/

extraction in ventilationsegments away from the fire.

5 – SOME TRANSALPINE TUNNELS5.4 Gotthard Road Tunnel – Air Velocity Control

System uses supply and extractions fans to guaranteeconverging flows to the extraction zone.

• PID controlled• Efficient +/-500 Pa• Regulation 5 min.

LBA LHO LGU LMO

-240

-210

-180

-150

-120

-90

-60

-30

0

-20

-15

-10

-5

0

5

10

15

20

0 2000 4000 6000 8000 10000 12000 14000 16000

Tota

l Pre

ssur

e [P

a]

Air S

peed

[m/s

]

x [m]

u [m/s]

p [Pa]

Air supply segmentAir extraction

MMI ScreenshotDp =-160 Pa

5 – SOME TRANSALPINE TUNNELS5.5 Fréjus Tunnel – Outline

5 – SOME TRANSALPINE TUNNELS5.6 Fréjus Road Tunnel – Main Data

• Today single bore, bidirectional traffic, 2nd bore (safetygallery) under construction

• Length 12.9 km• Slope +0.54%

(delta height heads 70 m)• Traffic space cross section 49 m2• Safety exits 34 (350 m, under construction)• Daily traffic volume 5’000 vehicles ( 50% trucks)• Ventilation system 1st bore (Semi-)transverse, 24 axial fans• Ventilation system 2nd bore Longitudinal with jet fans

and point extraction• Ventilation stations total 4, thereof 2 underground• Air velocity control 1st bore Air supply/extraction• Air velocity control 2nd bore Jet fans, PID controlled

5 – SOME TRANSALPINE TUNNELS5.7 Fréjus – Emergency ventilation existing bore

France(high pressure) Italy

(low pressure)

Tunnel

Gallery

130 m3/s

Bidirectional traffic

5 – SOME TRANSALPINE TUNNELS5.7 Fréjus – Emergency ventilation second bore

180 m3/s 0 m3/s

France Italy

RESUME

1. Today, emergency ventilation requirements are often moredesign relevant than sanitary ones, as the fresh air needsdecrease.

2. Long bidirectional tunnels must dispose of transverseventilation systems. This was the traditional solution fortransalpine tunnels because of high excavation costs.

3. For unidirectional bores with low to moderate traffic,longitudinal ventilation schemes may be applied (in somecountries). Today, efficient mechanized tunnel boringrenders a safe double-bore configuration attractive.

4. Air velocity control is essential and can be achieved eitherwith jet fans or with air supply/extraction away from the firesegment.