INTERNATIONAL SEMINAR LONG TUNNELS

Desafío para el Diseño, Construcción y Operación Challenges for Design, Construction and Operation

VENTILATION AND SECURITY IN LONG TRANSALPINE ROAD TUNNELS

Dr. Ing. EPFL Uwe Drost

17, 18 y 19 de Octubre 2012 Santiago, Chile

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? Typical long road tunnel • Passenger car fire • Truck fire, minor • Truck fire, major

fire probabilities: every 2-4 years every year every 8 years

Mont Blanc 1999

Gotthard-Tunnel 2001

Fréjus-Tunnel 2005

Tauerntunnel 1999

Via Mala 2006

Tunnel Croci, 22nd of September, 2012

1 – WHY VENTILATION?

2 - TRANSALPINE ROAD TUNNELS 2.1 Exemplary boundary conditions • • • • • • • • •

Long tunnels, length Altitude above seal level Vertical height between heads typically Difference between internal and external temperature Length of ventilation segments Shaft lengths Barometrical pressure differences between heads

Example: high pressure in central Europe, low pressure in Italy Delta-P Alps  500 Pa (5 mbar)

> 6-7 km up to 1900 m 50-150 m 15-30 K 2-5 km up to 850 m up to +/- 900 Pa

3 - SANITARY VENTILATION 3.1 Historical trend Very strong reduction of fresh air needs over the last two decades (factor 8-10) because of • Catalysts • Particulate filters • Optimized internal combustion

CO-emissions of a truck

 However: A residual visibility requirement will always remain because of abrasion (wheels, road) and dust raise. Visibility impact of a truck

3 - SANITARY VENTILATION 3.2 Example Pfändertunnel, 6.6 km Existing tube, 1980

Second tube, 2012

Fresh air section 10.5 m2

Fresh air section 4.5 m2

Traffic 6600 vehicles/day

Traffic 31’500 vehicles/day

(1982 bidirectional)

(2012 bidirectional)

3 - SANITARY VENTILATION 3.3 Ventilation schemes – unidirectional traffic Longitudinal with Saccardo nozzle

Longitudinal with Jet-Fans

Full-traversal ventilation

++ + --

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

++ + + o --

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

3 - SANITARY VENTILATION 3.4 Ventilation schemes – bidirectional traffic + + -

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

Semi-transverse supply ventilation

+ --

Constant air quality High ventilation power High CAPEX Bad initial fire conditions (air velocity, reaction time)

Semi-transverse exhaust ventilation

+ --

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

Full transverse Full-traversal ventilation ventilation

++ + -

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

Longitudinal ventilation with point exhaust

4 – EMERGENCY VENTILATION 4.1 Ventilation schemes Unidirectional traffic only, without congestion risk Longitudinal ventilation with jet fans (or Saccardo nozzles)

SMOKE EXPULSION

Unidirectional or bidirectional traffic

Smoke extraction through dampers

STRATIFICATION

4 – EMERGENCY VENTILATION 4.2 Regulatory requirements (>6 km) Country

Configuration for long unidirectional tunnels

Configuration for long bidirectional tunnels

Design fire size

Smoke extraction capacity (cross section 50 m2)

Austria

Smoke extraction through dampers

Smoke extraction through dampers

30 MW

120 m3/s

France

Longitudinal with point extraction every 5 km or smoke extraction through dampers

Smoke extraction through dampers

30 (200) MW

Point extraction: 200-250 m3/s Through dampers: 120 m3/s

Germany

Longitudinal with point extraction every 2 km or smoke extraction through dampers

Smoke extraction through dampers

30-100 MW

Point extraction: 225 m3/s Through dampers: 120 - 300 m3/s

Italy

Smoke extraction through dampers

Smoke extraction through dampers

30-200 MW

200-250 m3/s

Switzerland

Smoke extraction through dampers

Smoke extraction through dampers

30 MW

165-200 m3/s

USA

Longitudinal or extraction

Smoke extraction

According to vehicles

According to design calc’s

(alphabetic order)

RVS 09.02.31

Annex 2, 2000-63

RABT 2006

ANAS 2009

ASTRA 13 001

NFPA 502

5 – SOME TRANSALPINE TUNNELS 5.1 Overview Road Tunnel

Year

Type

Ventilation / velocity control

Fréjus tunnel 12.9 km

1980 / 2015

bidirectional, possibly unidirectional from 2015

(semi-) transverse/ longitudinal 4 stations velocity control: supply/exhaust, second tube 75 jet fans

Mont Blanc tunnel 11.6 km

1965

bidirectional

(semi-) transverse/ 2 stations velocity control: 76 jet fans

Gotthard tunnel 16.9 km

1980 / 2030

bidirectional / unidirectional from 2030

transverse/ 6 stations velocity control: supply/exhaust

Gran San Bernardo 5.8 km

1964

bidirectional

semi-transverse / 4 stations velocity control: none yet

San Bernardino 6.6 km

1967

bidirectional

semi-transverse / 4 stations velocity Control: jet fans

5 – SOME TRANSALPINE TUNNELS 5.2 Gotthard Road Tunnel – Outline

5 – SOME TRANSALPINE TUNNELS 5.3 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 ventilation segments away from the fire.

5 – SOME TRANSALPINE TUNNELS 5.4 Gotthard Road Tunnel – Air Velocity Control System uses supply and extractions fans to guarantee converging flows to the extraction zone. MMI Screenshot Dp =-160 Pa

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

u [m/s]

LBA

20

LHO

LGU

LMO

p [Pa]

0

15

-30 -60

5

-90

0

-120

-5

-150

-10

-180

-15

-210

-20

0

2000

4000

6000

8000 x [m]

10000

12000

14000

16000

-240

Total Pressure [Pa]

Air Speed [m/s]

Air supply segment

Air extraction

10

5 – SOME TRANSALPINE TUNNELS 5.5 Fréjus Tunnel – Outline

5 – SOME TRANSALPINE TUNNELS 5.6 Fréjus Road Tunnel – Main Data • • • • • • • • • • •

Today single bore, bidirectional traffic, 2nd bore (safety gallery) 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 TUNNELS 5.7 Fréjus – Emergency ventilation existing bore Bidirectional traffic

France (high pressure)

130 m3/s

Italy (low pressure)

Tunnel

Gallery

5 – SOME TRANSALPINE TUNNELS 5.7 Fréjus – Emergency ventilation second bore

Italy

France 180 m3/s

0 m3/s

RESUME 1. Today, emergency ventilation requirements are often more design relevant than sanitary ones, as the fresh air needs decrease. 2. Long bidirectional tunnels must dispose of transverse ventilation systems. This was the traditional solution for transalpine tunnels because of high excavation costs. 3. For unidirectional bores with low to moderate traffic, longitudinal ventilation schemes may be applied (in some countries). Today, efficient mechanized tunnel boring renders a safe double-bore configuration attractive. 4. Air velocity control is essential and can be achieved either with jet fans or with air supply/extraction away from the fire segment.