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

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

Tunnelling and Underground Space Technology 17 (2002) 153–158 2002 ITA Open Session: Fire and Life Safety ¨ Safety aspects of railway and road tunne...

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Tunnelling and Underground Space Technology 17 (2002) 153–158

2002 ITA Open Session: Fire and Life Safety

¨ Safety aspects of railway and road tunnel: example of the Lotschberg 夞 railway 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 safety measures are presented in this paper on a practical view for the first and on a theoretical view for the second. In view of the recent events of the year 2001 (terrorism act on the 11th of September and the Gotthard fire on the 24th of October) particular attention should be turned on related safety aspects. 䊚 2002 Elsevier Science Ltd. All rights reserved.

1. Introduction The serious accidents, which happened in the MontBlanc and Tauern tunnels in 1999 and more recently in the Gotthard Tunnel, have highlighted the intrinsic difficulties of road and goods traffic in tunnels. Most of the countries with tunnels as part of their national infrastructures have established special ‘Task Forces’ which have decreed directives and instructions concerning traffic in road and rail tunnels. The road works undertaken in the framework of renovation and improvement of the Mont-Blanc Tunnel (11.6 km long) are intended to ensure its safety and are presented in the first part of this paper. In the second part the safety ¨ aspects of the Lotschberg rail tunnel project are analysed (35 km long) construction of which began in 1998 and will be completed in 2007. The catastrophic fire of October 2001 in the Gotthard Tunnel has highlighted the performance of ventilation systems, the dangers potentiality of goods transportation and the human factor. North–South Traffic and goods transport in Europe have to pass through the Alps where the relief and climate concentrate the links to few options, particularly 夞 This article was presented at the ITA Open Session: Fire and Life Safety, at the 28th ITA General Assembly and World Tunnel Congress, 2–8 May 2002, Sydney, Australia. *Corresponding author. Tel.: q41-21-618-1505; fax: q41-21-6181122. E-mail address: [email protected] (F. Vuilleumier).

to tunnels for convenience. Due to increasing traffic throughout the years, particularly goods transportation, these bottlenecks are overloaded (not to mention the traffic increase due to the momentarily closure of one or more of the links). Therefore, even if fewer accidents happen intrinsically in tunnels compared to the remaining networks, their configuration increases the consequences. As the probability of accidents raises in parallel to the traffic increase, safety aspects have to be improved. Fig. 1. 2. The Mont-Blanc road tunnel 2.1. Presentation and characteristics of the tunnel The Mont-Blanc tunnel, which represents a major road artery between France and Italy, is situated under the Mont-Blanc massif, the roof of Western Europe. At 11.6 km, the Mont-Blanc tunnel was the longest road tunnel in the world at the time of its completion in 1965. The traffic in this single tube, two lanes and relatively small cross-section tunnel can be very heavy. The traffic is characterised by a great deal of asymmetry (in both directions) and a high percentage of heavy goods vehicles. The amount of light vehicle traffic has increased by a factor of 2 while the amount of heavy goods vehicles has increased by a factor 17. These figures show the importance of the tunnel for trade between France and Italy.

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

Vehicles loaded with dangerous goods are not allowed to use the tunnel. As shown by the disastrous 1999 fire, this ban has not been enough to prevent the occurrence of major accidents. 2.2. Refurbishing of the Mont-Blanc road tunnel Following the March 1999 incident and subsequent to the court inquiry, the objectives of refurbishing have been defined as the repair of the damages caused by the accident and the installation of fittings and equipment, but foremost, to establish a global concept which will ensure the tunnel’s safety. In the case of an accident or some other emergency, the safety measures aim at achieving the following objectives: – Detecting abnormal situations and warning tunnel users. – Providing protection and evacuation routes for tunnel users as well as access to rescuers. – Assisting the self-protection of tunnel users and the fire-fighting by tunnel users. The equipment and the arrangements that have been made are described hereafter.

situated between the tunnel and the refuge. These refuges are ventilated through fresh air ducts and put under light overpressure thereby imposing an air flux, which flows from the refuge into the tunnel. They are equipped with telephones, closed circuit TV cameras and public address system. In case of a fire in front of the refuge, the temperature inside should not exceed 35 8C after 4 h. Fire-fighting facilities are located at each portal and one fire-fighting facility is located at the centre of the tunnel. Fire fighters are continuously present, thus reducing the time they need to be on hand in the event of any emergency. The fire-fighting facilities are equipped with computer network terminals, telephones, closed circuit TV, radios as well as one heavyweight, and one lightweight fire truck. They are directly connected to the escape gallery. The rescuers can get to the refuges and evacuate the victims from outside the tunnel via escape galleries situated in underground fresh air galleries. In this case the fresh air ventilation is reduced to a minimum. At each end of the galleries airlocks have been installed to permit evacuation at station level. The escape gallery is lighted throughout its length and equipped with emergency telephones. A motorised evacuation vehicle has been provided to facilitate the evacuation of injured or disabled 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, fire extinguishers (with sensors that detect when they have been removed) and electric sockets for rescue services. They are also equipped with glass doors (with sensors to detect when they have been opened) and are clearly indicated by means of specific signs. The fire-fighting network is made up of fire-fighting recesses located every 150 m with a hydrant every 300 m on the north side wall (direction Italy–France) at the left of the refuges. 2.2.4. Ventilation

2.2.1. Lay-bys and turning bays In both directions a lay-by is situated every 600 m allowing heavy goods vehicles to stop. Also every 600 m a turning bay allows maintenance and rescue vehicles to operate in the tunnel. 2.2.2. Refuges, fire-fighting facilities and escape galleries The refuges are situated on one side of the tunnel only and are spaced at intervals of 300 m. Their layout has been designed so as to protect occupants from the direct atmosphere of the tunnel by means of an airlock, Fresh air ventilation. Fresh air is uniformly distributed through each of the eight ventilation sections by fans connected to its specific fresh air gallery, which provide 82.5 m3 ys at maximum power. Sanitary ventilation maintains the air quality in the tunnel. Fire ventilation. The fire ventilation system is a key element in the new safety concept of the tunnel and has been redesigned in order to achieve the two following objectives: massive smoke extraction in a limited

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section surrounding the position of a fire and active control of the longitudinal velocity (smoke propagation management). These objectives are intended to allow tunnel users to ensure their own safety in reaching the refuges and, allowing rescuers to better fight the fire. The concept chosen is a semi-transversal ventilation system. The extraction capacity of 150 m3 ys (using 7 exhaust ducts) is achieved by: – 2 fans for vitiated air at each portal and one for redundancy. – 4 booster fans in the extraction duct. – Exhaust ducts every 100 m with dampers. The control of the longitudinal air velocity in the tunnel is achieved with 76 accelerators placed along the tunnel roof. Their purpose is to get a zero longitudinal velocity at the centre of the fire, in order to keep the smoke stratified. 2.2.5. Closed circuit TV monitors, radio-communication system and heat sensors Closed circuit TV monitors allow all refuges and bays in the tunnel to be monitored, and are supported by cameras placed half way up the walls allowing surveillance even in case of a fire. 150 cameras have been placed in the tunnel (one every 150 m on each wall side) to allow complete and uninterrupted surveillance of each section of tunnel. The radio-communication system allows rescuers from different services to communicate with each other as well as informing tunnel users of the situation and giving them instructions in several languages (12 different FM channels). The heat sensors detect any rise in temperature along the tunnel roof, in the refuges and the bays. An algorithm calculates the fire location. 2.2.6. Electricity, control rooms and network All the electronic equipments in the tunnel can be operated by either of the two tunnel portals, both under normal circumstances and in case of fire. In the event that both tunnel (French and Italian) power supplies should fail simultaneously, twin redundant inverters would come on line and provide emergency power during 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 exhaust dampers. At each tunnel portal and at the fire fighting facility control rooms have been set up. All the IT systems and network 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 transportation junction and transit country in the middle of Europe despite the obstacle imposed on it by the Alps. In the last thirty years, the transportation of goods between the North and South of Europe has increased by a factor of six. 3.1.2. The consequences in Switzerland With the overloaded transportation network (rail and road), the environment is badly affected by noise and pollution. The quality of life and road safety are decreasing along the major highways. The saturation limits have long been exceeded. 3.1.3. The Alp transit Switzerland has been able to convince the European Community of the need to pursue a coherent transportation policy. With the Transit Agreements, the combined rail and road traffic also include Europe. The role of the Alps is preserved for tourism and for the protection of the environment, because trains do not emit so many noxious substances. Alp Transit, the new railway 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. ˆ – 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 traffic on the Gotthard. – The Simplon route connected to the French TGV (Macon–Geneva) will connect the French part of Switzerland to the northern part of Italy and France. – The traffic routes east of Switzerland will be improved (Zurich–St-Gall). ¨ 3.1.4. The Lotschberg base tunnel ¨ The Lotschberg base tunnel will be built to accept different classes of trains, from goods transportation to passenger trains. The tunnel will also accommodate high-speed trains and therefore will be designed for a maximal speed of 250 kmyh. Basically the tunnel is a two-tube tunnel comprising a rail tunnel East and West. But in the first phase the two-way tunnel will be open from Raron (South Portal) to the north of the emergency station in Ferden. The remaining part of the tunnel northwards will be a oneway tunnel as far as train operation is concerned (except at the North Portal in Frutigen).


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3.2. Safety concept of the tunnel Despite railways being a statistically safe form of transportation (due to guidance per rails, professional drivers, etc.) rail accidents may still happen. Even if accidents occur less often in tunnels (e.g. no level crossings, which cause most of the train-related accidents) the severity of the accidents increase seriously due to the tunnel configuration, not to mention the psychological impact attributed to such events. In Switzerland, the last accidents with fatalities occurred in ¨ 1971 and in 1932. The safety concept of the Lotschberg tunnel should bring a substantial improvement compared to the existing lines of the rail network. With a partial two-tube tunnel, access via two galleries, as well as a window gallery and reconnaissance gallery, an essential improvement in rail tunnel safety should be achieved. 3.2.1. Safety philosophy Safety is considered basically as the characteristic of quality, which has to be guaranteed throughout its life period. It is based on the following four elements: – Protection objectives (‘protection of the endangered person’ i.e. passengers, personal, etc. and ‘protection of the natural environment, the constructions and technical installations and their use’ by order of importance). – 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 which are applicable to the relevant circumstances. The operator of the railway is responsible for its installations and the safety measures. In relation to the opening of the railway network for ‘free access’, international jurisdiction takes on new importance. Protection objectives and safety measures play a very important role for the operator.

2. A Quantitative Risk Analysis is used on the relevant hazard scenarios derived from step 1 only where this previous step was not able to define appropriate measures. Using international and domestic statistical data (available in Switzerland from the CFF and the BLS) and considering the effects of the safety measures, each event is quantified with the frequency of its occurrence and the extent of its consequences. In order to better define the remaining risks after having taken all essential preventive and curative measures, (so-called ‘residual risk’), the representation used is the frequency–consequences diagram, which allows for optimisation of the safety measures by means of applying specific assessment criteria and evaluating the acceptability of the risk in order to adjust said assessment criteria. The diagram is sub-divided into three ranges: – (red area): Overall railway risk: unacceptable for new railway 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 the irrelevant risk, the risk is to be reduced as far as it is technically and operationally possible and should be contained within reasonable limits. The risk assessment has been carried out taking the following 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 objectives have been identified. A new tunnel cannot be designed without adopting the following measures:

3.2.2. Methodology of the risk assessment As part of the complex process of constructing a long railway tunnel, a safety analysis and concept serve the future operator to guarantee a high level of safety. The procedure consists of two steps:

– 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.

1. A Qualitative Safety Analysis in order to limit the range of accident scenarios and related concepts, and to identify appropriate safety measures for all tunnel sections. It should also define the appropriate laws and applicable national and international norms and regulations.

The measures will also affect the rolling materials, but, as the tunnel will be open to free access, requirements of materials on trains cannot be guaranteed. Due to the length of the tunnel and the difficulties involved for rescuers to get to the scene of the accident, selfrescue measures are essential during the initial phase.

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Fig. 2. F–C Diagram.

The safety measures should also ensure that rescuers are able to accomplish their duties. 3.2.4. Self-rescue The event sequences, which have occurred in the past in tunnels, show that a great priority has to be attributed to self-rescue measures, particularly during a fire. Given the 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, those people who are able to escape rapidly have a fair chance of getting themselves to safety on their own. Therefore, the following aspects have to be considered: – 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 parties In 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 on fire from entering the tunnel. Should this occur, or in the event that a train should catch fire in the tunnel,

experience has revealed that the train will continue to roll a considerable distance (20 km). Two stations, the service station Mitholz (which can later be transformed into an emergency station) and the emergency station Ferden situated approximately 20 km from the opposite portal, will greatly facilitate self-rescue, evacuation and intervention of the rescuers. Of course, it stands to reason that there can be no certainty that trains will be able to stop at these stations. It is therefore necessary that any safety concept include scenarios for a train stopping along the entire length of the tunnel. The service station Mitholz will serve as a rescue station in the event that a train on fire stops in the station. A platform the length of the station (approx. 440 m) will cater for victims of an emergency, who will then be moved to the reconnaissance gallery Kandertal. From there, they will pass through airlocks and be evacuated by buses. Ventilation will be raised to its maximum capacity in order to ensure a safe environment for the self-rescue of the passengers from the service station to the reconnaissance gallery. The emergency station Ferden is made up of two rail stations, one per tunnel (East and West) with a length of 450 m. A platform will enable the victims of an accident to use one of the six escape galleries spaced at intervals of 85 m and which lead to a protected and ventilated zone between the two tunnels. Any injured travellers can be picked up by ambulance, which can enter the tunnel from the Ferden dip gallery and reach this zone via the lock under the ventilation station of Ferden. The evacuation of any victims will follow by train via the safe tunnel.


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In an emergency mode, the fresh air ventilation system in Ferden will provide air to the escape zone and the safe tunnel as well as to the tunnel, where the train is on fire by passing through the escape galleries. Any victims fleeing the scene will thus have a safe escape route free of smoke. Smoke is extracted via seven dampers, one of which will be opened nearest to the position of the fire, so as to ensure optimal extraction of smoke as well as maximum visibility in the tunnel. The smoke is extracted by the 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 of the emergency station (i.e. in the twin tunnel), the evacuation of passengers shall occur through communication branches spaced every 333 m. nearest the location where the train has stopped. Another train will then take the victims to the exterior of the tunnel. The ventilation system will go into emergency mode; the fresh air system (station Ferden) will blow its maximum air capacity at the same time that the exhaust system ¨ will begin extracting at its maxi(station Fystertella) mum air capacity. This should create a pressure difference between the safety zone and the tunnel with the train under fire in order to prevent the smoke from hampering any escape efforts through communication branches. Coherent planning is needed in order to provide for the safe passage of trains, to allow the rescue train access to the tunnel and to prevent any other trains from entering the tunnel during an emergency. Planning is also 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 being renovated, the other for rail traffic and currently being constructed) have been the subject of study. Despite their differences, numerous similarities exist: – The consequences of what might at first appear to be an incident of a relatively harmless nature can rapidly take on dramatic proportions. – In the case of fire, the most dreaded incident, the smoke 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 accident are very similar. In this last case scenario, the time it takes rescuers to get to the scene is often longer than life expectancy in an emergency situation. Victims of an accident or emergency must be able, in an initial phase, to take charge of their own rescue (self-rescue). The route along where evacuation takes place or rescuers progress to the site of fire must not be located in the affected tunnel. An escape gallery or tunnel or other access route must provide access to the scene of the accident as well as allowing victims to be evacuated. Tunnel operators and fire fighters must be subject to regular drills, which must be as realistic as possible. Past experience and experiences currently being acquired in the area of tunnel security aim at constructing or improving tunnel infrastructure in order to: – Detect abnormal situations and rapidly inform tunnel workers and users of any danger. – Provide protection and facilitate evacuation of tunnel users and access of rescue workers. – Optimise preparations in view of the possibility of fire. The tunnels studied put into practice the maximum number of measures for obtaining the highest security objectives. Nevertheless, the risk factor will never be reduced to zero even though we must do everything in our power to reduce the risks to the greatest extent possible. The recent fire on 24th October 2001 in the Gotthard tunnel shows the physical limitation of an appropriate ventilation system when heavy goods vehicles are involved in such an event. A full tank capacity provides an energy of the magnitude of 30 MW during 15 min, without taking into account the goods being carried in the vehicle. Therefore, it should be analysed if the tank capacity shouldn’t be decreased. Furthermore, shouldn’t directives on the material and construction of the fuel tank be revisited? After the dramatic terrorist attacks of September 2001, a reassessment of the critical event ‘Terrorism and Violence’ should be considered. Even if a terrorist act happening in a tunnel cannot be as impressive as the 11th September, nevertheless, the psychological and media impact would be colossal.