S Siemens Building Technologies Fire Safety 1 Fire Safety Concept for Tunnels Dublin, May 6th 2004 Customized Fire Safety Concept for Underground Transportation

Fire Safety 1

s

Siemens Building Technologies

Fire Safety Concept for TunnelsDublin, May 6th 2004

Customized Fire Safety Concept for

Underground Transportation Facilities

Dr. Peter StahlSiemens Building Technologies AG

Fire Safety

Fire Safety 2

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Critical Key Factors on Personal Safety in Road Tunnels

non controllable fires are representing the highest risk probability

wide range of potential damage as a consequence

• severe damage to people

and killed people

• huge damage on

tunnel infrastructure

• long shut down periods

(toll tunnels)

Fire Safety 3

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Key Factors on Damage to People

focus on people close to the fire zone and on fire brigades approaching

the fire zone

• lack of fire detection and alarming systems

• toxic fire gases

• immense formation of heat: radiation and convection

• strongly limited visibility

• lack of escape routes

• lack of evacuation systems: visible and acoustic

• panic or passive reaction of people close to the fire zone

Fire Safety 4

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Thermal Heat Caused by Fires in Road Tunnels

5 MW2 m2 fuel15 Min

20 MW8 m2 fuel

20..60 Min

20 m3/s smoke 60 m3/s smoke

Standard Fire

Fire Safety 5

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Heat Distribution Caused by Tunnel Fires

direct approach to the fire without any controlled intervention

almost impossible1000

800

600

400

200

0 50 100 150- 150 - 100 - 50

distance from fire core [m]

tem

per

atu

re [

°C]

truck

bus

motor car (plastic body)

motor car

Fire Safety 6

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Smoke Formation in Tunnels

• combustible: 20 l gasoline + 5 l gas oil

• distance to camera: 60 m

• wind speed: 1,5 m/s (towards camera)

Fire Safety 7

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Fire Development in a Tunnel: e.g. Road Tunnel

flash over to neighbourhood car as critical key factor

• full scale dire of a car after approx. 10-15 min

• full scale fire of a truck after approx. 20-60 min

available time to for any intervention is strongly limited !

• alarming and closing of tunnel for further new traffic

• information and evacuation of people close to the risk zone

• activation of active fire protection or controlled ventilation systems

• approaching the fire core by the fire brigades

Fire Safety 8

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Fire Protection in Tunnels Needs an Overall Concept

structural and organisational measures are first important steps

of such a concept

cooling of the risk zone as key issue

• personal safety as first priority of the fire protection concept– reduction of the temperatures in the risk zone– increasing the visibility in the risk zone: key to escape and to approach

• protection of the tunnel infrastructure– temperature reduction of the concrete elements below 100°C

• protection from hazadorous scenario– temperature reduction in the risk zone to avoid flash over from one vehicle to

another

Fire Safety 9

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Siemens Fire Safety Concept for Tunnels: e.g. Road Tunnel

• early warning by fire detection using video cameras– early pre-alarm– control station: focus of video cameras to the potential risk zone – activation of first traffic control measures

• fast localisation of the fire within 2-4 m without any influence by the tunnel wind within latest 3 min after start of the fire

– alarming– visual verification– activation of alarm management procedures

• activation of active intervention system– Preferable solution: water spray system

Fire Safety 10

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Video

Video

Trafficevent

detection

Smokeevent

detection

!

1 2 3 4 5 6

Dangerof life in carsinvolved inaccident

Risk

Open car fire

Time [min]

Automaticextinguishing release

Start of fire fightingby the fire brigade

Development towardsa possible disaster

!Danger of life

in cars notinvolved inaccident

Heavy damageson tunnel

infrastructure

10 ... 30

Warning

Fire Detection

In developpement

Fire Safety 11

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Fire Extinguishing in Road Tunnels: The Key Objectives

first priority on personal safety: people in the risk zone

approaching fire brigades

a tunnel fire can not be fully extinguished but, fully controlled

• reduction of fire intensity at the fire core

• to avoid flash over from one vehicel to another

• temperature reduction of the toxic fire gases at the end of a 30 m

risk zone below 50°C

• scrubbing effect on fire gases to increase visibility

Fire Safety 12

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Siemens Fire Extinguishing Concept for Road Tunnels

use of the automatic CerSpray extinguishing system with optimised

droplet spectrum for fire in road tunnels

no influence of wind speed until 10 m/s

30 m

sector

30 m

sector

30 m

sector

fire alarm

localisation

30 m

sector

30 m risk zone

90 m protection zone

automatic CerSpray tunnel extinguishing system

Fire Safety 13

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FibroLaser II: The Optimum Fire Detection System for Tunnels

localisation of the fire within 1-3 m and 2-3 minutes up to high wind speeds

of 10 m/s without having the risk of false alarms

FibroLaser II cable

wind

firedevelopment

reaction zone

free jet plume

mixture of burning material

air

heat exchange to the cable (radiation, convection)

transient heat conduction

radiation

Fire Safety 14

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FibroLaser II: The Detection Cable

production up to 4 km cable length without any problem

Fire Safety 15

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Use of Physical Back-Scattering Effect in Glass Fibres

corelasersource

detector forback scattering

mechanical stressheat changes

Fire Safety 16

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Basic Physical Effect: Raman Scattering

stokes line

nm1020980940

anti stokes line

original laser light

Inte

nsi

ty

spectral position

solid state element

back scatering

laser wave

heat movement

Fire Safety 17

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FibroLaser II: International References

up to now more than 350 km of cable and 250 OTS controllers are

installed world-wide

• Melbourne City Link Tunnel (Australia)

• Taipeh MTR (Taiwan)

• MTR Bangkok (Thailand)

• Mont Blanc Tunnel (France)

• Arlberg Tunnel (Austria)

• St. Bernhardino (Switzerland)

• Remsteig Tunnel (Germany)

• Orte (Italy)

Fire Safety 18

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Automatic extinguishing system: Protection objective

Primary objective is the fire limitation until the arrival of the

intervention forces to the risk zone

a total extinguishment cannot be guaranteed

• Reduction of the fire intensity at the fire source

• Prevention of the jump of fire to neighboured vehicles

• Cooling of smoke gases at the end of the 30 m protection zone

below 50°C

• Washing out of the smoke gases to raise the visibility


Fire Safety 19

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Dimensioning of the automatic extinguishing system

Basis: expectable heat power of the fire source at the

time of fire detection and localisation after three

minutes (about 20-30 MW)

• Spray water system with a optimised droplet spectrum and a control principle with is fitted to the installation conditions

• Effectiveness must be guaranteed at wind velocities of up to 10 m/s

• Spraying time of minimum 30 min or longer, if the approaching ways of the intervention forces are very far

• Engineering of the extinguishing system with physical model which is verified by experiments at a pilot plant


Fire Safety 20

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0

20

40

60

80

100

120

140

0 5 10 15 20 25 30

Extinguishing Length [m]

Tem

per

atu

re o

f G

ases

[°C

]

10 MW

20 MW

Two-lane road tunnel: Cooling of smoke gases

Wind: 5 m/s, Discharge: 6 mm/min, Droplet: 0.3 mm

Fire Safety 21

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0

50

100

150

200

250

300

0 5 10 15 20 25 30


Tem

pera

ture

of

Gases [

°C]

1 m/s

3 m/s

5 m/s

10 m/s


Fire: 20 MW, Discharge: 6 mm/min, Droplets: 0.3 mm


Fire Safety 22

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0

25

50

75

100

125

150

0 5 10 15 20 25 30


Te

mp

era

ture

of

Ga

se

s [

°C]

2 mm/min

4 mm/min

6 mm/min

8 mm/min


Fire: 20 MW, Wind: 5 m/s, Droplets: 0.3 mm


Fire Safety 23

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0

25

50

75

100

125

150

0 5 10 15 20 25 30


Tem

pera

ture

of

Gases [

°C]

0,1 mm

0,3 mm

0,5 mm

1,0 mm


Fire: 20 MW, Wind: 5 m/s, Discharge: 6 mm/min


Fire Safety 24

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0

2.5

5

7.5

10

12.5

15

0 0.5 1 1.5 2 2.5

Droplet Diameter [mm]

Dis

tan

ce F

ire c

en

tre-F

loo

r w

ett

ing

[m

]

Two-lane road tunnel: Wetting of the floor

Fire: 20 MW, Wind: 5 m/s, Discharge: 6 mm/min


Fire Safety 25

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Results

The tunnel fire can be controlled until the intervention forces arrive:

• Smoke gases are cooled below 50°C

• The jump of fire is prevented

This is independent of

• the tunnel wind,

• possible up to fires of 20 MW (Worst Case at activation).


Fire Safety 26

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Results

The droplet diameter is optimised between 100 and 300 m depending

on the actual situation:

• large enough, to prevent the jump of fire

• small enough, to cause a sufficient cooling effect

The water discharge is optimised between 2 and 6 mm/min :

• sufficient to lead to the necessary cooling effect

• O2-fraction is non-critical after 30 m (minimum 16.5 Vol-% )

• economical storage still possible


Fire Safety 27

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Set-up of the test installation

Verification of the physical model with a pilot installation (scale 1:3)

allows the model usage to design real tunnel applications (Up-Scaling)

Similarity approach as in wind channels/ process engineering

Fire detection -system

Wind

5m/s 3,3

m

Autobrand

B2

C2

C1

2 m 2 m 4 m

CO2

B1

Wind

5m/s 3,3

m

Autobrand

B2

C2

C1

2 m 2 m 4 m

CO2

B1

Nozzles


Fire Safety 28

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0

25

50

75

100

125

150

0 5 10 15 20 25 30

Löschstrecke [m]

Tem

pera

tur

Bra

nd

gase [

°C]

2 mm/min

4 mm/min

6 mm/min

8 mm/min

Hagerbach-Pilot plant: Cooling of the smoke gases

Fire: 1.4 MW, Wind: 2.8 m/s, Droplet: 0.25 mm

25

30

35

40

45

50

55

0 1 2 3 4 5 6 7


Tem

pera

ture

of

Gases [

°C]

6.6 mm/min9.9 mm/min12.6 mm/min

""


Fire Safety 29

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Scaling (Scale-up/ Scale-down)

The following quantities have to stay constant when scaling:

a) specific heating related to cross-section :

b) specific extinguishing capacity:

c) specific droplet velocity in the reaction zone:

Tunnel

Fire

A

*Q

Feuer

Fire

*Q

*Q

Gas

Droplet

w

w


Fire Safety 30

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Conclusion

• The physical model allows the design of extinguishing system for real tunnel applications

• The physical model is verified by pilot tests

• The engineering gives for a two-lane road tunnel a optimum design at a droplet diameter between 100 and 300 m and a water discharge between 2 and 6 mm/min

• The protection of life in tunnels makes complete protection concepts necessary which must contain an automatic extinguishing system

• An automatic water extinguishing system – optimised for tunnel application can fulfil the comprehensive protection objectives

• Sprinklers cannot match the declared protection objectives


Documents

S Siemens Building Technologies Fire Safety 1 Fire Safety Concept for Tunnels Dublin, May 6th 2004 Customized Fire Safety Concept for Underground Transportation