Lötschberg Safety

7/30/2019 Ltschberg Safety

1/6

Tunnelling and Underground Space Technology 17 (2002) 153158

0886-7798/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved.PII: S 0886- 7798 0 2 .0 0 0 1 8 - 4

2002 ITA Open Session: Fire and Life Safety

Safety aspects of railway and road tunnel: example of the Lotschbergrailway tunnel and Mont-Blanc road tunnel

F. Vuilleumier*, A. Weatherill, B. Crausaz

BG Consulting Engineers Ltd, Avenue De Cour 61, P.O. Box 241, CH1001, Lausanne, Switzerland

Abstract

After serious accidents, which happened in tunnels in the last few years, most countries have established Task Forces in order

to evaluate the safety of existing tunnels and to establish new safety measures. Based on two actual examples, the new safetymeasures are presented in this paper on a practical view for the first and on a theoretical view for the second. In view of therecent events of the year 2001 (terrorism act on the 11th of September and the Gotthard fire on the 24th of October) particularattention should be turned on related safety aspects. 2002 Elsevier Science Ltd. All rights reserved.

1. Introduction

The serious accidents, which happened in the Mont-Blanc and Tauern tunnels in 1999 and more recently inthe Gotthard Tunnel, have highlighted the intrinsic dif-

ficulties of road and goods traffic in tunnels. Most ofthe countries with tunnels as part of their nationalinfrastructures have established special Task Forceswhich have decreed directives and instructions concern-ing traffic in road and rail tunnels. The road worksundertaken in the framework of renovation and improve-ment of the Mont-Blanc Tunnel (11.6 km long) areintended to ensure its safety and are presented in thefirst part of this paper. In the second part the safetyaspects of the Lotschberg rail tunnel project are analysed

(35 km long) construction of which began in 1998 andwill be completed in 2007.

The catastrophic fire of October 2001 in the Gotthard

Tunnel has highlighted the performance of ventilationsystems, the dangers potentiality of goods transportationand the human factor.

North South Traffic and goods transport in Europehave to pass through the Alps where the relief andclimate concentrate the links to few options, particularly

This article was presented at the ITA Open Session: Fire andLife Safety, at the 28th ITA General Assembly and World TunnelCongress, 28 May 2002, Sydney, Australia.

*Corresponding author. Tel.: q41-21-618-1505; fax: q41-21-618-1122.

E-mail address: [email protected] (F. Vuilleumier).

to tunnels for convenience. Due to increasing trafficthroughout the years, particularly goods transportation,these bottlenecks are overloaded (not to mention thetraffic increase due to the momentarily closure of oneor more of the links). Therefore, even if fewer accidents

happen intrinsically in tunnels compared to the remain-ing networks, their configuration increases the conse-quences. As the probability of accidents raises in parallelto the traffic increase, safety aspects have to beimproved. Fig. 1.

2. The Mont-Blanc road tunnel

2.1. Presentation and characteristics of the tunnel

The Mont-Blanc tunnel, which represents a majorroad artery between France and Italy, is situated underthe Mont-Blanc massif, the roof of Western Europe. At

11.6 km, the Mont-Blanc tunnel was the longest roadtunnel in the world at the time of its completion in1965.

The traffic in this single tube, two lanes and relativelysmall cross-section tunnel can be very heavy. The trafficis characterised by a great deal of asymmetry (in bothdirections) and a high percentage of heavy goods vehi-cles. The amount of light vehicle traffic has increasedby a factor of 2 while the amount of heavy goodsvehicles has increased by a factor 17. These figuresshow the importance of the tunnel for trade betweenFrance and Italy.


2/6

154 F. Vuilleumier et al. / Tunnelling and Underground Space Technology 17 (2002) 153158

Fig. 1. Rail and road links through the Alps.

Vehicles loaded with dangerous goods are not allowedto use the tunnel. As shown by the disastrous 1999 fire,this ban has not been enough to prevent the occurrenceof major accidents.

2.2. Refurbishing of the Mont-Blanc road tunnel

Following the March 1999 incident and subsequentto the court inquiry, the objectives of refurbishing havebeen defined as the repair of the damages caused by theaccident and the installation of fittings and equipment,but foremost, to establish a global concept which willensure the tunnels safety.

In the case of an accident or some other emergency,the safety measures aim at achieving the followingobjectives:

Detecting abnormal situations and warning tunnelusers.

Providing protection and evacuation routes for tunnelusers as well as access to rescuers.

Assisting the self-protection of tunnel users and thefire-fighting by tunnel users.

The equipment and the arrangements that have beenmade are described hereafter.

2.2.1. Lay-bys and turning bays

In both directions a lay-by is situated every 600 mallowing heavy goods vehicles to stop. Also every 600m a turning bay allows maintenance and rescue vehiclesto operate in the tunnel.

2.2.2. Refuges, fire-fighting facilities and escape

galleries

The refuges are situated on one side of the tunnelonly and are spaced at intervals of 300 m. Their layouthas been designed so as to protect occupants from thedirect atmosphere of the tunnel by means of an airlock,

situated between the tunnel and the refuge. Theserefuges are ventilated through fresh air ducts and putunder light overpressure thereby imposing an air flux,which flows from the refuge into the tunnel. They areequipped with telephones, closed circuit TV camerasand public address system. In case of a fire in front of

the refuge, the temperature inside should not exceed 358C after 4 h.

Fire-fighting facilities are located at each portal andone fire-fighting facility is located at the centre of thetunnel. Fire fighters are continuously present, thus reduc-ing the time they need to be on hand in the event ofany emergency. The fire-fighting facilities are equippedwith computer network terminals, telephones, closedcircuit TV, radios as well as one heavyweight, and onelightweight fire truck. They are directly connected tothe escape gallery.

The rescuers can get to the refuges and evacuate the

victims from outside the tunnel via escape galleriessituated in underground fresh air galleries. In this casethe fresh air ventilation is reduced to a minimum. Ateach end of the galleries airlocks have been installed topermit evacuation at station level. The escape gallery islighted throughout its length and equipped with emer-gency telephones. A motorised evacuation vehicle hasbeen provided to facilitate the evacuation of injured ordisabled victims.

2.2.3. Emergency recesses, fire-fighting recesses and

network

Within the tunnel, emergency recesses have been

placed alternately at intervals of approximately 100 m.They are equipped with an emergency telephone, fireextinguishers (with sensors that detect when they havebeen removed) and electric sockets for rescue services.They are also equipped with glass doors (with sensorsto detect when they have been opened) and are clearlyindicated by means of specific signs. The fire-fightingnetwork is made up of fire-fighting recesses locatedevery 150 m with a hydrant every 300 m on the northside wall (direction ItalyFrance) at the left of therefuges.

2.2.4. Ventilation

2.2.4.1. Fresh air ventilation. Fresh air is uniformlydistributed through each of the eight ventilation sectionsby fans connected to its specific fresh air gallery, whichprovide 82.5 m ys at maximum power.3

Sanitary ventilation maintains the air quality in thetunnel.

2.2.4.2. Fire ventilation. The fire ventilation system is akey element in the new safety concept of the tunnel andhas been redesigned in order to achieve the two follow-ing objectives: massive smoke extraction in a limited


3/6

155F. Vuilleumier et al. / Tunnelling and Underground Space Technology 17 (2002) 153158

section surrounding the position of a fire and activecontrol of the longitudinal velocity (smoke propagationmanagement).

These objectives are intended to allow tunnel usersto ensure their own safety in reaching the refuges and,allowing rescuers to better fight the fire.

The concept chosen is a semi-transversal ventilationsystem. The extraction capacity of 150 m ys (using 73

exhaust ducts) is achieved by:

2 fans for vitiated air at each portal and one forredundancy.

4 booster fans in the extraction duct.

Exhaust ducts every 100 m with dampers.

The control of the longitudinal air velocity in thetunnel is achieved with 76 accelerators placed along thetunnel roof. Their purpose is to get a zero longitudinal

velocity at the centre of the fire, in order to keep thesmoke stratified.

2.2.5. Closed circuit TV monitors, radio-communication

system and heat sensors

Closed circuit TV monitors allow all refuges and baysin the tunnel to be monitored, and are supported bycameras placed half way up the walls allowing surveil-lance even in case of a fire. 150 cameras have beenplaced in the tunnel (one every 150 m on each wallside) to allow complete and uninterrupted surveillanceof each section of tunnel.

The radio-communication system allows rescuersfrom different services to communicate with each otheras well as informing tunnel users of the situation andgiving them instructions in several languages (12 differ-ent FM channels).

The heat sensors detect any rise in temperature alongthe tunnel roof, in the refuges and the bays. An algorithmcalculates the fire location.

2.2.6. Electricity, control rooms and network

All the electronic equipments in the tunnel can beoperated by either of the two tunnel portals, both undernormal circumstances and in case of fire. In the eventthat both tunnel (French and Italian) power suppliesshould fail simultaneously, twin redundant inverterswould come on line and provide emergency powerduring one hour for safety functions such as lighting,refuges, escape ways of the current section, the GTC,telephone network, closed-circuit TV monitor system,the public address system, signal sensors and exhaustdampers.

At each tunnel portal and at the fire fighting facilitycontrol rooms have been set up. All the IT systems andnetwork are redundant.

3. The Lotschberg rail base tunnel

3.1. Presentation and characteristics of the tunnel

3.1.1. Switzerland a country of transit

Switzerland has always been an important transpor-

tation junction and transit country in the middle ofEurope despite the obstacle imposed on it by the Alps.In the last thirty years, the transportation of goodsbetween the North and South of Europe has increasedby a factor of six.

3.1.2. The consequences in Switzerland

With the overloaded transportation network (rail androad), the environment is badly affected by noise andpollution. The quality of life and road safety are decreas-ing along the major highways. The saturation limitshave long been exceeded.

3.1.3. The Alp transit

Switzerland has been able to convince the EuropeanCommunity of the need to pursue a coherent transpor-tation policy. With the Transit Agreements, the combinedrail and road traffic also include Europe.

The role of the Alps is preserved for tourism and forthe protection of the environment, because trains do notemit so many noxious substances. Alp Transit, the newrailway link, will easily permit crossing to the Alps.This project is based on four constituent elements:

The key element will be the new and additional

railway route Arth-Goldau Lugano with the Gotthard(57 km) and Monte-Ceneri (13 km) base tunnels.

The base railway route from Frutigen to the Rhone

valley (Lotschberg Tunnel, 34.6 km) will complete

the picture in order to avoid a concentration of trafficon the Gotthard.

The Simplon route connected to the French TGV(MaconGeneva) will connect the French part ofSwitzerland to the northern part of Italy and France.

The traffic routes east of Switzerland will beimproved (ZurichSt-Gall).

3.1.4. The Lotschberg base tunnelThe Lotschberg base tunnel will be built to accept

different classes of trains, from goods transportation topassenger trains. The tunnel will also accommodatehigh-speed trains and therefore will be designed for amaximal speed of 250 kmyh.

Basically the tunnel is a two-tube tunnel comprisinga rail tunnel East and West. But in the first phase thetwo-way tunnel will be open from Raron (South Portal)to the north of the emergency station in Ferden. Theremaining part of the tunnel northwards will be a one-way tunnel as far as train operation is concerned (exceptat the North Portal in Frutigen).


4/6


3.2. Safety concept of the tunnel

Despite railways being a statistically safe form oftransportation (due to guidance per rails, professionaldrivers, etc.) rail accidents may still happen. Even ifaccidents occur less often in tunnels (e.g. no level

crossings, which cause most of the train-related acci-dents) the severity of the accidents increase seriouslydue to the tunnel configuration, not to mention thepsychological impact attributed to such events. In Swit-zerland, the last accidents with fatalities occurred in1971 and in 1932. The safety concept of the Lotschberg

tunnel should bring a substantial improvement comparedto the existing lines of the rail network. With a partialtwo-tube tunnel, access via two galleries, as well as awindow gallery and reconnaissance gallery, an essentialimprovement in rail tunnel safety should be achieved.

3.2.1. Safety philosophySafety is considered basically as the characteristic ofquality, which has to be guaranteed throughout its lifeperiod. It is based on the following four elements:

Protection objectives (protection of the endangeredperson i.e. passengers, personal, etc. and protectionof the natural environment, the constructions andtechnical installations and their use by order ofimportance).

Danger analysis and evaluation of risk. Safety measures Implementation.

These objectives are considered to be obtained when: Principle 1: all necessary measures have been met in

relation to the potential danger. Principle 2: all necessary measures have been met in

relation to the technical and scientific standards whichare applicable to the relevant circumstances.

The operator of the railway is responsible for its in-stallations and the safety measures. In relation to theopening of the railway network for free access, inter-national jurisdiction takes on new importance. Protectionobjectives and safety measures play a very importantrole for the operator.

3.2.2. Methodology of the risk assessment

As part of the complex process of constructing a longrailway tunnel, a safety analysis and concept serve thefuture operator to guarantee a high level of safety. Theprocedure consists of two steps:

1. A Qualitative Safety Analysis in order to limit therange of accident scenarios and related concepts, andto identify appropriate safety measures for all tunnelsections. It should also define the appropriate lawsand applicable national and international norms andregulations.

2. A Quantitative Risk Analysis is used on the relevanthazard scenarios derived from step 1 only where thisprevious step was not able to define appropriatemeasures. Using international and domestic statisticaldata (available in Switzerland from the CFF and theBLS) and considering the effects of the safety meas-

ures, each event is quantified with the frequency ofits occurrence and the extent of its consequences.

In order to better define the remaining risks afterhaving taken all essential preventive and curative meas-ures, (so-called residual risk), the representation usedis the frequencyconsequences diagram, which allowsfor optimisation of the safety measures by means ofapplying specific assessment criteria and evaluating theacceptability of the risk in order to adjust said assess-ment criteria.

The diagram is sub-divided into three ranges:

(

red area)

: Overall railway risk: unacceptable for newrailway lines. (yellow area): ALARP (As Low As Reasonably

Practicable) Criteria: overall railway risk. (green area): Irrelevant overall railway risk Fig. 2.

In the area limited by the unacceptable risk and theirrelevant risk, the risk is to be reduced as far as it istechnically and operationally possible and should becontained within reasonable limits.

The risk assessment has been carried out taking thefollowing critical events into consideration:

Industrial accidents.

Accidents involving injury (passengers, others). Fire (all type of trains) Derailments. Collisions. Losses of hazardous goods. Operation failures. Terrorismyviolence.

3.2.3. Objectives

From the results of the risk analysis, several objectiveshave been identified. A new tunnel cannot be designedwithout adopting the following measures:

Measures to prevents incidents (appropriate conveys,railway well-maintained).

Measures to reduce fatalities and damages. Measures to improve self-rescue opportunities. Measures to improve the possibilities of external

rescue.

The measures will also affect the rolling materials,but, as the tunnel will be open to free access, require-ments of materials on trains cannot be guaranteed. Dueto the length of the tunnel and the difficulties involvedfor rescuers to get to the scene of the accident, self-rescue measures are essential during the initial phase.


5/6

157F. Vuilleumier et al. / Tunnelling and Underground Space Technology 17 (2002) 153158

Fig. 2. FC Diagram.

The safety measures should also ensure that rescuers areable to accomplish their duties.

3.2.4. Self-rescue

The event sequences, which have occurred in the pastin tunnels, show that a great priority has to be attributedto self-rescue measures, particularly during a fire. Giventhe great velocity at which a fire spreads and due to the

high temperature, reduction of oxygen concentration,loss of visibility and propagation of toxic fumes, thosepeople who are able to escape rapidly have a fair chanceof getting themselves to safety on their own.

Therefore, the following aspects have to beconsidered:

Length of escape paths and indicators. Equipment along the escape gallery (lighting,

ventilation). Communication infrastructure (telephone, radio, etc.). Education for tunnel users.

3.2.5. Rescue by third partiesIn order to facilitate the job of external rescuers, some

measures have to be considered such as:

Accessibility of tunnel portal. Accessibility to the scene of the accident (extraction

of and fresh air supply). Rapidity of intervention (training, planning, etc.).

3.2.6. Service and emergency stations

The safety measures will prevent a train already onfire from entering the tunnel. Should this occur, or inthe event that a train should catch fire in the tunnel,

experience has revealed that the train will continue toroll a considerable distance (20 km). Two stations, theservice station Mitholz (which can later be transformedinto an emergency station) and the emergency stationFerden situated approximately 20 km from the oppositeportal, will greatly facilitate self-rescue, evacuation andintervention of the rescuers. Of course, it stands toreason that there can be no certainty that trains will be

able to stop at these stations. It is therefore necessarythat any safety concept include scenarios for a trainstopping along the entire length of the tunnel.

The service station Mitholz will serve as a rescuestation in the event that a train on fire stops in thestation. A platform the length of the station (approx.440 m) will cater for victims of an emergency, who willthen be moved to the reconnaissance gallery Kandertal.From there, they will pass through airlocks and beevacuated by buses.

Ventilation will be raised to its maximum capacity inorder to ensure a safe environment for the self-rescue ofthe passengers from the service station to the reconnais-sance gallery.

The emergency station Ferden is made up of two railstations, one per tunnel (East and West) with a lengthof 450 m. A platform will enable the victims of anaccident to use one of the six escape galleries spaced atintervals of 85 m and which lead to a protected andventilated zone between the two tunnels. Any injuredtravellers can be picked up by ambulance, which canenter the tunnel from the Ferden dip gallery and reachthis zone via the lock under the ventilation station ofFerden. The evacuation of any victims will follow bytrain via the safe tunnel.


6/6


In an emergency mode, the fresh air ventilation systemin Ferden will provide air to the escape zone and thesafe tunnel as well as to the tunnel, where the train ison fire by passing through the escape galleries. Anyvictims fleeing the scene will thus have a safe escaperoute free of smoke.

Smoke is extracted via seven dampers, one of whichwill be opened nearest to the position of the fire, so asto ensure optimal extraction of smoke as well as maxi-mum visibility in the tunnel. The smoke is extracted bythe ventilation station Fystertella through a ventilation

shaft.

3.2.7. Safety concept in case of fire outside (South) of

the emergency station

In case a burning train has come to a stop south ofthe emergency station (i.e. in the twin tunnel), theevacuation of passengers shall occur through communi-

cation branches spaced every 333 m. nearest the locationwhere the train has stopped. Another train will then takethe victims to the exterior of the tunnel. The ventilationsystem will go into emergency mode; the fresh airsystem (station Ferden) will blow its maximum aircapacity at the same time that the exhaust system(station Fystertella) will begin extracting at its maxi-

mum air capacity. This should create a pressure differ-ence between the safety zone and the tunnel with thetrain under fire in order to prevent the smoke fromhampering any escape efforts through communicationbranches.

Coherent planning is needed in order to provide for

the safe passage of trains, to allow the rescue trainaccess to the tunnel and to prevent any other trains fromentering the tunnel during an emergency. Planning isalso required in order to organise rescue operations.

4. Conclusion

Two tunnels, both differing strongly from one another(one for road traffic and in the process of beingrenovated, the other for rail traffic and currently beingconstructed) have been the subject of study. Despitetheir differences, numerous similarities exist:

The consequences of what might at first appear to bean incident of a relatively harmless nature can rapidlytake on dramatic proportions.

In the case of fire, the most dreaded incident, thesmoke and heat can rapidly cause the scene and the

surrounding area to become a potentially fatal place. The problems encountered when evacuating tunnel

users and getting rescuers to the scene of the accidentare very similar.

In this last case scenario, the time it takes rescuers toget to the scene is often longer than life expectancy inan emergency situation. Victims of an accident oremergency must be able, in an initial phase, to takecharge of their own rescue (self-rescue).

The route along where evacuation takes place orrescuers progress to the site of fire must not be locatedin the affected tunnel. An escape gallery or tunnel orother access route must provide access to the scene ofthe accident as well as allowing victims to be evacuated.

Tunnel operators and fire fighters must be subject toregular drills, which must be as realistic as possible.

Past experience and experiences currently beingacquired in the area of tunnel security aim at construct-

ing or improving tunnel infrastructure in order to:

Detect abnormal situations and rapidly inform tunnelworkers and users of any danger.

Provide protection and facilitate evacuation of tunnelusers and access of rescue workers.

Optimise preparations in view of the possibility offire.

The tunnels studied put into practice the maximumnumber of measures for obtaining the highest securityobjectives. Nevertheless, the risk factor will never bereduced to zero even though we must do everything in

our power to reduce the risks to the greatest extentpossible.The recent fire on 24th October 2001 in the Gotthard

tunnel shows the physical limitation of an appropriateventilation system when heavy goods vehicles areinvolved in such an event. A full tank capacity providesan energy of the magnitude of 30 MW during 15 min,without taking into account the goods being carried inthe vehicle. Therefore, it should be analysed if the tankcapacity shouldnt be decreased. Furthermore, shouldntdirectives on the material and construction of the fueltank be revisited?

After the dramatic terrorist attacks of September 2001,

a reassessment of the critical event Terrorism andViolence should be considered. Even if a terrorist acthappening in a tunnel cannot be as impressive as the11th September, nevertheless, the psychological andmedia impact would be colossal.

Documents

Lötschberg Safety