Tunnel safety concept for the new railway line Divaa - Koper

Tunnel safety concept for the new railway line Diva a - Koper Dr.Dipl.Ing. Rudolf Bopp Gruner, ZT GmbH, Wien; Austria Angelo Žigon, univ.dipl.inž.grad...
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Tunnel safety concept for the new railway line Diva a - Koper Dr.Dipl.Ing. Rudolf Bopp Gruner, ZT GmbH, Wien; Austria Angelo Žigon, univ.dipl.inž.grad. Marko Žibert, univ.dipl.inž.grad. ELEA-iC, Ljubljana

Abstract The new railway line planned between the city of Diva a and the port of Koper is characterised by a sequence of tunnels and viaducts separated only by short stretches of open line. Due to the high proportion of tunnels and the difficult access to the line particular attention must be paid to the development of a safety concept. The paper focuses on tunnel safety concept for the railway line on subsection rni Kal – Koper which is designed and will be executed as a 1st stage of the new railway line. Nevertheless the paper gives a short overview of the whole project. The main infrastructural safety measures such as the escape routes and the rescue areas near the portals are described. As an example of a technical safety measure the tunnel ventilation concept is presented. Keywords: Tunnels, Safety concept, Safety in tunnels, Railway, V. corridor

Povzetek Zna ilnost novega odseka železniške proge med Diva o in pristaniškim mestom Koper je zaporedje predorov in viaduktov, ki jih lo ujejo kratki odseki odprte trase. Glede na velik delež trase, ki poteka v predorih in težko dostopnost je potrebno posebno pozornost nameniti izdelavi varnostnega koncepta. Prispevek se osredoto a na predstavitev koncepta za pododsek rni Kal – Koper, ki je v terminskem planu izvedbe postavljen v 1. fazo, hkrati pa podaja kratek pregled celotnega projekta. Opisani so vsi pomembnejši infrastrukturni varnostni ukrepi kot so ubežne poti, reševalne površine in postaja na portalnih obmo jih. Kot primer tehni nega varnostnega ukrepa je predstavljena zasnova prezra evanja.

Bopp, R., Žigon, A., Žibert, M.: Koncept varnosti v predorih za novo železniško progo Diva a - Koper

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

1 Introduction Port of Koper is one of most important centers of logistics and freight transportation in Slovenia. In year 1967 the new single track railway line was opened to connect flourishing port with middle European cities. After 1990 the business growth almost tripled and with more ambitious projects ahead a need for a higher capacity railway line was evident. A new single track railway line between Koper and Diva a was proposed in a corridor which is a: part of V. pan-European transportation corridor Venice – Kiev and part of VI. trans-European transportation corridor Lyon – Budapest

Since the negotiations with Republic of Italy over the alignment of new railway section were not finished in time the client (Government of Republic of Slovenia - Ministry for Transportation) decided to move ahead with first stage from Koper to rni Kal which probably will not be part of the main corridor. This new high capacity railway line will run predominantly through tunnels. As safety measures may greatly influence the tunnel design, tunnel safety aspects must be considered in an early phase of the project and some fundamental decisions have to be taken. As these decisions influence not only the safety but have also wide impacts on the construction and operation costs of the new railway line a close examination is necessary.

Figure 1: Location of the railway line regarding pan-european and trans-european corridors

The paper gives first some information on the relevant guidelines for tunnel safety and the approach for the development of a tunnel safety concept. In a second part the most important safety measures which have been decided for the Diva a - Koper project are described.

2 Project overview 2.1 General description In order to cope with immediate ascent of the terrain in Koper hinterland the alignment of the high capacity railway line travels rather through tunnels in constant gradient than in many twists on open section like the existing line. The whole section of railway line alignment from Koper to Diva a is characterized

by two distinctive subsections (see Figure 2). The first section with 6 tunnels and two long viaducts leads from Koper to rni Kal with a length of 12.135 km where alignment gains height traveling just under the surface on the slopes of Tinjan hill in big circular section and ends with crossing Osp Vally with long viaduct. The second section from rni Kal to Diva a with a length of 15.061 km travels through 2 deep long straight tunnels in karstic region. Only the first section will be described in further text. More than 7.5 km out of 12.1 km of the railway line from Koper to rni Kal travels through tunnels. The distance between portals of consecutive tunnels in the upper part of this section is very short. Tunnels T3 to T7 must therefore be considered as one long tunnel (see also Table 1)

10. SLOVENSKI KONGRES O CESTAH IN PROMETU, Portorož, 20. – 22. oktobra 2010

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

Figure 2: The general layout of the railway alignment

Figure 3: The longitudinal profile of the railway line

Table 1: Description of the tunnels on subsection Koper – rni Kal Tunnel


T3 T4 T5 T6 T7 T8

330 m 1947 m 115 m 335 m 1150 m 3760 m

Tunnel Set

Start Ch.

End Ch.

Length of tunnel set




4360 m




3760 m

2.2 Description of a typical tunnel Typical tunnel on the new railway line is a single track, single tube NATM tunnel consisting of primary shotcrete lining, waterproof layer and cast in place concrete lining. Typical inner dimension of horseshoe like form of normal cross section is width/height

=6’7m/7’0m, designed around demanded modified GC train clearance profile (see Figure 4). With a possible future second tube in mind the cross section is designed as symmetrical thus track (width=3’40m) is positioned in the axis of the tunnel with raised emergency walkway (width=1’65m) located on both sides. Bellow walkways the space for

10. SLOVENSKI KONGRES O CESTAH IN PROMETU, Portorož, 20. – 22. oktobra 2010

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

supply and telecommunication cabling is provided. The track structure is designed as a slab track system sitting on tunnel invert concrete.

2.3 Operation of the new line The railway line will be used mainly by freight trains climbing the ascent from the port of Koper towards Diva a. Nevertheless the railway line is designed for both freight and passenger trains (see Table 2) in both directions driving in bundles of 3 to 5 trains.

Table 2: Overview of traffic characteristics Type


IC/EC Pendolino Freight trains direction to Koper Freight trains direction to Diva a

3 pairs of trains/day 2 pairs of trains/day 45 (fully loaded) or 57 (dynamic ut. ) 50 (fully loaded) or 63 (dynamic ut. )

Length of train (max./average) 400 m/250 m 82 m/82 m 750 m/500 m



160 km/h 160 km/h 120 km/h


750 m/500 m

80 km/h


Figure 4: Typical NATM tunnel cross section

In accordance with TSI RST HS only trains category B shall be used in passenger traffic on the new railway line. This category demands that in case of fire the train is capable of driving at least 80km/h for next 15 minutes ignoring emergency brakes and maintaining means of communication. Currently a 3kV DC (direct current) supply catenary system is planned. In future a 25kV 50Hz AC system is foreseen.

3 Guidelines 3.1 European and national guidelines The main risks in railway tunnels are fire, collision and derailment. As a fire in a passenger train is a major and specific hazard in tunnels with potentially catastrophic consequences, discussions about tunnel safety

10. SLOVENSKI KONGRES O CESTAH IN PROMETU, Portorož, 20. – 22. oktobra 2010

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

often concentrate on this type of incident. However this limited perception must be abandoned when a safety concept for a railway line as the Diva a -Koper line is developed. The elaboration of a tunnel safety concept is a quite complex task where an important number of aspects and subsystems must be considered. There are however only few guidelines on safety in railway tunnels which can be consulted. The most important are the technical specification of interoperability relating to ‘safety in railway tunnels’ in the trans-European conventional and high-speed rail system, the so called TSI SRT 0. These relatively new specifications define for a first time a minimal safety standard for railway tunnels in Europe. However TSI SRT specifies only few mandatory safety measures. In addition to the safety measures specified in the TSI SRT, the guidelines of the UIC Codex 779-9 0 concerning tunnel safety should be considered. The UIC document gives a good overview over a more general set of possible safety measures and provides additional information concerning the efficiency of different safety measures. Along with the European guidelines there are a number of national guidelines as for example the German EBA guideline 0 or the Swiss guideline SIA 197 0, 0. In Austria the guideline of the national fire fighting association has to be considered 0. These national guidelines ask to some extent for additional safety measures and they often do specify the needed measures in more detail. This may lead to a different set of safety measures when different national guidelines are used (see examples in chapter 3.3). In the absence of national guidelines and lack of most recent national experience in railway tunnel safety, as it is the case in Slovenia, the development of a specific railway tunnel safety concept is therefore a long process which has to involve a various authorities (see chapter 4.2).

3.2 Application of guidelines In the application of the different guidelines the following problems may appear: National guidelines are normally stricter than the regulations of the TSI SRT. When comparing different national guidelines different safety measures may result.

3.2.1 Comparison between TSI SRT and national guidelines The most important infrastructural safety measures specified in the TSI SRT are: Escape distance: The maximum distance of cross passages (in double bore tunnels or in tunnels with a parallel service and safety tunnel) or distance of emergency exits in single bore tunnels is stipulated in the TSI SRT (maximum 500 m for tunnels with a parallel tube or maximum 1000 m for a double track tunnel). Escape walkways: Lateral walkways inside the tunnel with a minimal width of 0.7 m must be provided. Rescue areas at tunnel portals: In the vicinity of the tunnel portals enough space for the deployment of the rescue services is needed. The TSI SRT defines a minimal area of 500 m2. The fact that some of the very long double bore tunnels planned or built in the last years, have considerably lower distances between cross passages (see table 3) shows that in the application of the TSI SRT and national guidelines different solutions may result. This is not only true for the distance of cross passages but also for the width of the escape walkway which is normally bigger than 0.7 m or the rescue areas at portals which are normally considerably larger than 500 m2 as stipulated in the TSI SRT.

Table 3: Distances of cross passages in long railway tunnels Tunnel Channel Tunnel Lötschberg Base Tunnel Tunel de Guardarrama Great Belt Tunnel

Length 50.5 km 34.6 km 28.4 km 8.0 km

Cross passages 375 m 333 m 250 m 250 m

Special features lorry transport underground emergency station underwater tunnel

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cording to the German EBA guideline airlocks without any mechanical installation to prevent a propagation of smoke to the parallel tunnel tube (safe area) are possible, whereas in Austria a mechanically generated overpressure is requested.

3.2.2 Comparison between national guidelines Consulting different national guidelines may lead to contradictory recommendations as the following examples show: Water supply for fire fighting: In Germany dry water pipes in all tunnels longer than 500 m are mandatory whereas in Switzerland normally rescue trains (mobile water supply) are used and no fixed water pipes are foreseen in railway tunnels. In Austria permanently filled or dry pipes are demanded. However in very long tunnels as the 32.8 km long Koralmtunnel 0 or the 27 km long Semmering-Base Tunnel 0 the water is brought into the tunnel by a rescue train and a fixed water supply system is planned only in the underground emergency station. Ventilation: Another example is the ventilation of cross passages which connect two parallel tunnel tubes. Ac-

4 Approach to develop a safety concept for a railway tunnel 4.1 Subsystems Although in tunnel projects major focus is put on infrastructural safety measures it has to be pointed out that tunnel safety depends not only on infrastructural measures but on a bigger number of subsystems. Figure 5 gives an overview over these subsystems. All of them are equally important and have to be considered in the development of a tunnel safety concept.

Health & Safety Conditions Professional Qualifications


Tunnel Safety

Maintenance Rules


Operation Rules

Rolling Stock

Figure 5: Subsystems relevant for railway tunnel safety according to 0


Basic principles

Although there is no generally accepted state of the art for tunnel safety some generally agreed principles do exist. So the design of a tunnel must allow the self-rescue and

evacuation of train passengers and staff. Furthermore provisions for the rescue services to rescue people in the event of an incident in a tunnel shall be provided. Appropriate safety measures should be considered when a tunnel safety concept is developed.

Bopp, R., Žigon, A., Žibert, M.: Koncept varnosti v predorih za novo železniško progo Diva a - Koper

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

According to 0 and 0 there are the 4 following categories of measures which can be discerned: Prevention of incidents, Mitigation of impact of accidents, Facilitation of escape, Facilitation of rescue. The order in which these categories are listed reflects their decreasing effectiveness to

reduce the risk in a railway tunnel (see Figure 6). It is important to note that measures preventing an incident in the tunnel (e.g. emergency brake neutralisation during a tunnel passage) are much more effective than measures which improve the self rescue (facilitation of escape) of passengers or measures which support the rescue services (facilitation of rescue). The strength of railways lies in the prevention of accidents.

Risk in tunnels




Safe side

Residual risk Rescue

Figure 6: Hierarchy of safety measures

A safety concept generally consists of a combination of infrastructure (civil and technical), operations and rolling stock measures, which should be combined in a manner to achieve an optimised concept. The definition of specific safety measures in a project should be based on an assessment of the risk (risk based safety concept).

4.3 Safety management group There is not only a big number of subsystems which must be considered in the elaboration of a safety concept, but also the different stakeholders involved in the planning process (national authorities, the owner, the designer of the tunnel and the technical installations, contractor(s), operator, emergency services as fire fighters). It is therefore recommended that a safety concept is developed in a safety management group 0 which goes along with the project over all project phases. The safety management group will normally be a "living structure/organism" which has to adapt to the changing needs during the different phases of the project.

One of the very important tasks of the safety management group is the definition of specific (quantitative or qualitative) safety goals. The instruments to check the achievement of these safety goals and the methods to assess the (residual) risk should be defined. Furthermore the key decisions should be systematically recorded and the contents of the safety documents for the procedure of approval by the authorities as well as the documents, which will be used in the operation phase, should be defined in an early stage of the project.

5 Key elements of the safety concept rni Kal - Koper 5.1 Infrastructural safety measures In the early phase of the project the infrastructural measures had to be defined as a basis for the planning of the tunnels. The most important measures are:

10. SLOVENSKI KONGRES O CESTAH IN PROMETU, Portorož, 20. – 22. oktobra 2010

Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

5.1.1 Tunnel system Single track tunnels: All tunnels are single track, so that there are no switches in the tunnels. The risks associate with train crossings and derailment are thus reduced. Escape routes: Special lateral escape galleries in longer tunnels (T4, T7) will be built. The maximum distance between to escape galleries is 660 m. For the longest tunnel (T8) a parallel safety tunnel with cross passages to the railway tunnel every 500 m is planned. In the railway tunnels on both sides a lateral walkway is available. The width of the lateral walkway is 1.65 m and the walkway on the side which leads to the escape galleries / cross passages is equipped with a handrail. Fire protection for structures: The zones where tunnels cross critical infrastructures as the highway Koper Ljubljana with low overburden special reinforcement of the tunnel structure is foreseen to guarantee the stability of the tunnel for a sufficient time in the case of a fire in the tunnel. Collection of water and liquids: In addition to the drainage system to collect the rock water, a separate de-watering system is foreseen in the tunnels to drain forge water or toxic liquids in case of a spillage of dangerous goods. These liquids are collected by a separate drainage tube which is equipped with siphons in regular intervals and which is connected to a retention basin at the lower tunnel portal.

5.1.2 Emergency stop area The probability that a burning train can' t reach the portal (safe area) increases with increasing tunnel length. Therefore, according to TSI SRT "appropriate provisions must be laid down to take account of the particular safety conditions in very long tunnels". As the

Diva a - Koper line consists of a continuous succession of tunnels and viaducts there is no natural place, where a train could be stopped and evacuated in the case of a fire. The situation is thus comparable with a very long tunnel. In the case of a train fire a modern passenger train should maintain its movement capability for 15 minutes 0. Assuming a train speed of 80 km/h a train can thus travel a distance of about 20 km. Therefore in tunnels which are significantly longer than 20 km normally an emergency station is foreseen, where a tunnel can be stopped and evacuated 0, 0. This safety measure which can drastically reduce the severity of a train fire is also implemented in the Diva a - Koper project. At km 16.1, which is approximately in the middle of the section with the 8 tunnels an emergency stop area is planned at the lower portal of Tunnel T2. A platform with a length of 400 m allows a fast and safe evacuation of a train. Due to the limited space a part of the platform will be located on the viaduct. The area is equipped with lighting, communications facilities, video control, etc and can be accessed by road vehicles.

5.1.3 Portal areas and access to tunnels The roads which are built for the construction of the tunnels will serve as access roads to the tunnel in the operation phase. Despite the mountainous area each tunnel portal can be reached by road vehicles. Totally 6 portal areas with a surface of minimum 1500 m2 and 7 portal places with a surface of minimum 500 m2 are available for emergency services. The slab track is not trafficable by road vehicles. Access into the tunnel is ensured by two way vehicles (road - rail) of the fire fighters. Additionally rolling pallets for the transport of injured passengers and material will be available at the portals of the tunnels and the escape galleries.

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Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

Figure 5: Typical section of layout for safety concept showing rescue areas, equipment provided, emergency routes for rescuers and time prognoses,….

5.2 Technical safety measures Beside the infrastructural safety measures a big number of technical safety measures are planned. The most important are given below:

5.2.1 Ventilation Whereas longer road tunnels are generally equipped with a mechanical ventilation system, railway tunnels normally do not have a mechanical ventilation system because there is no exhaust from combustion engines which has to be removed from the tunnel. If railway tunnels are equipped with ventilation system, the primary goal is to guarantee smoke free areas (a safe area according to TSI SRT). This is normally achieved by a positive pressure compared to the incident tube. It has to be noted however, that it is not state of the art to use the ventilation in rail tunnels to control the smoke movement in the incident tunnel itself. In the Crni-Kal section of Diva a - Koper project the following ventilation system are planned: Ventilation of service tunnel (T8): The 3.8 km long tunnel T8 has a parallel service tunnel with ventilation buildings on both sides. A mechanical ventilation system is needed to remove the waste heat of the technical equipment which is placed in technical rooms which are located in the cross passages. Additionally the ventilation system

must guarantee a sufficient airflow through open escape doors in the case of a fire. The fans, which are located at both portals of the service tunnel, bring air into the service tunnel to generate an overpressure to the railway tunnel. On both sides 2 fans are foreseen, so that even in the case of one fan failing, still more than 75% of the maximum airflow can be delivered. This partly redundancy is important because the waste heat has to be removed permanently from the tunnel to guarantee a safe operation of the technical equipment. In each of the 7 cross passages a door is foreseen separating the railway tunnel from the safe area. To maintain the overpressure in the parallel service tunnel during self rescue and access of rescue services both portals are equipped with an airlock. Ventilation of escape galleries (T4, T7): As there is no need to remove waste heat from technical installation in the escape galleries in normal operation a simpler ventilation system is possible. The escape galleries of tunnels T4 and T7 are equipped with an air lock which is situated at the exit of the escape gallery. At the other end of the escape gallery an escape doors separates the safe area from the railway tunnel. Above the airlock a single fan is foreseen which is able to provide an airflow through the

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Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper

escape door which is high enough to prevent smoke penetrating in the escape gallery.

5.2.2 Water for fire fighting All tunnels are equipped with hydrants at a distance of 125 m. The water pipe, which is permanently filled, is supplied by 3 basins with a volume of 200 m3 each. A pressure between 6 and 12 bar is assure at all points and 800 l/min can be supplied.

5.2.3 Measures to facilitate rescue Table 4: Safety measures to facilitate self rescue Measure Emergency lighting

Remarks Illuminated walkway (minimum 1 lux) and escape galleries, brigther illumination of escape doors illuminated signs at a distance of 50 m on escape walkway, reflecting signs between the illuminated signs

Escape signage

Table 5: Safety measures to facilitate rescue Measure Segmentation of overhead line Earthling devices for overhead line Electricity supply 230V / 400V Communication radio for emergency services 2 Way vehicle to facilitate access to tunnel Rolling pallets

Remarks segment < 5 km (details still to be defined in a later project phase) details still to be defined power sockets at distance of 125 m based in Koper at portals of main tunnels and at portal of escape galleries

5.3 Operational safety measures and train safety Beside the infrastructural and technical safety measures also the trains and the operational procedures do have an important impact on the safety level. Passenger trains of category B will be used. Actually there are no restrictions for freight trains and/or transportation of dangerous goods foreseen. Further studies, especially on the transportation of dangerous good should be undertaken in the next project phase. In the case of an emergency situation fast operational action is needed. Only few decisions and relatively simple operational measures are necessary in the case of a train fire. The most important operational measures in an emergency situation are: Trains following the emergency train are stop immediately. Whenever possible it should be avoided that two trains are in a tunnel. Trains in front of the emergency train continue their journey. The emergency train itself should not stop inside a tunnel. The train tries to

reach the emergency stop area resp. to the end of the line. The detail operational procedures in a case of an accident will be specified in a later phase of the project.

References TSI SRT, "Safety in railway tunnels in the transEuropean conventional and high-speed rail system", 2008/163/EC UIC leaflet 779-9, Safety in Railway Tunnels, August 2003 Anforderungen des Brand- und Katastrophenschutzes an den Bau und den Betrieb von Eisenbahntunneln, Eisenbahn Bundesamt, 1.07.2008 SN 505 197, SIA 197, Projektierung Tunnel, Grundlagen, SIA Zürich 2004 SN 505 197/1, SIA 197-1, Projektierung Tunnel, Bahntunnel, SIA Zürich 2004 ÖBFV-RL A12, "Bau und Betrieb von neuen Eisenbahntunnel bei Haupt- und Nebenbahnen, Anforderungen des Brand- und Katastrophenschutzes" Richtlinie, Österreichischer Bundesfeuerwehrverband, Ausgabe 2000

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Bopp, R., Žigon, A., Žibert, M.: Tunnel safety concept for the new railway line Diva a - Koper Bopp, Burghart, Harer, Koinig, Neumann - "Incident management in a very long railway tunnel", 3rd International Symposium on Tunnel Safety and Security, 12-14 March, Stockholm, Sweden

Bopp, Langer, Neumann, Wagner, The ventilation and tunnel safety concept for the New Semmering Base Tunnel, Südbahntagung, Leoben 2009 Long Tunnels at great depth, ITA working Group no 17, ITA Report No 004, April 2010

10. SLOVENSKI KONGRES O CESTAH IN PROMETU, Portorož, 20. – 22. oktobra 2010