WP4 – Screening of concepts of protection against rock fall in

- VERSION NUMBER -1

- , 2014 -

WP4.4.2 –Screening of concepts of protection against rock fall in Slovenia

- FINAL VERSION -

State-of-the-Art in Risk Management Technology: Implementation and Trial for Project: Usability in Engineering Practice and Policy Institution: Geological Survey of Slovenia External experts: Hidrotehnik d.d. Date: November 2014

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DELIVERABLE SUMMARY

PROJECT INFORMATION Project acronym: START_it_up Project title: State-of-the-Art in Risk Management Technology: Implementation and Trial for Usability in Engineering Practice and Policy Contract number: 11-5-3-AT Starting date: September 2013 Ending date: November 2014 Project website address: http://startit-up.eu/ Lead partner organisation: Federal Ministry of Agriculture, Forestry, Environment and Water Management, Dep. IV/5 - Torrent and Avalanche Control Service, Austria Address: Marxergasse 2, 1030 Project manager: Florian Rudolf-Miklau E-mail: [email protected]

DELIVERABLE INFORMATION Title of the deliverable: Screening of concepts of protection against rock fall in Slovenia WP/activity WP4/ Activity 4.4.2 related to the deliverable: Type: Internal WP leader: Irstea, Grenoble regional center, Snow avalanche engineering and torrent control research unit External experts: Hidrotehnik d.d. Author: Jože Papež E-mail: [email protected], Keywords: Rockfall, protection, Slovenia This report should be cited in bibliography as follows:

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CONTENT 1 INTRODUCTION 5 2 Rockfall protection on Slovenian road network 5 3 Rockfall protection on Slovenian rail network 6 3.1 PARAMOUNT SLOVENIAN TEST BED 6 3.2 HAZARD & RISK MAPPING 7 3.3 ROCKFALL PROTECTION CONCEPTS & MEASURES 7 4. CONCLUSIONS 9

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SCREENING CONCEPTS OF PROTECTION AGAINST ROCK FALL IN SLOVENIA (PARAmount project)

1 INTRODUCTION

Regarding general protection concept agains rockfall and snow avalanches, investigated in the project, exist significant difference between road and railway infrastructure. In protection of road against rockfall hazard in last 15-20 years dominated manly modern flexible and certificated rockfall protection barriers. The slovene railway is from this point of view on the beginning. At the railways are dominated system for early warning and alerting called EAN or NOJP and rigid catching wooden-fences and simple light rigid mesh-fences. Many of these measures are loosing partially or completely their efficiency and functionality after an occured impact or because of lacking maintenance work.

2 ROCKFALL PROTECTION ON SLOVENIAN ROAD NETWORK

In Slovenia larger rockfall phenomena, like large scale failures, are not very common. They occur in the seismically active Upper Soča valley and even there are limited to smaller areas. More frequently we face rockfall and blockfall that put at risk residential and business premise, roads and railroads. Data, gathered by PUH d.d., show that rockfall is a major hazard for 175 km i.e. 2,8% of the total of 6.215 km state roads. Ever more frequent and intensive weather extremes and continuous increase of damage potential are calling for regular supplementing of rockfall hazard assessment and selection of reliable and durable solutions. In selection of the solutions, environmental adequacy is ever more important. The problems are solved with measures of active and passive protection. The analysis of adequacy of the carried out rocfall control measures sets guidelines for the future action. The principles of rockfall protection are determined by the extent of hazard. Where there is risk of large scale failures, spatial measures are the most rational solution. The line of the roads should be deviated, or protected by adequately designed galleries when this is not possible. In case of rockfall and blockfall hazard the method of primary or secondary active protection depends mostly on location and magnitude of the phenomena with regard to the structure at risk, to technical possibilities and to environmental acceptance of control measures.

Fig. 1, 2: The Polica slope on highway Ljubljana – Obrežje; situation before and after the measures carried out in 2005 Primary protection is carried out on the areas where rockfall phenomena occur. Standard rockfall control was carried out with plain or reinforced mesh drape, with which the falling rocks were restrained. In recent years deep 5

anchored steel wire mesh with high tension strength is coming forward because it enables also slope stabilisation and revegetation of very steep slopes. In Slovenia this system of rockfall control was carried out in the largest extent on the slopes Polica (Fig. 1, 2) and Mali vrh on the Malence – Višnja gora highway. In both cases the system proved

to be very successful. Fig. 3, 4: Rockfall control measures – combination of stone masonry, mesh with high tension strength and rockfall barriers on the top of the first slope on highway Razdrto-Divača (2006) Secondary protection is used when rocks have already been released. For retaining loose rocks we use up to date rockfall barriers that can retain falling rocks and boulders as well. Depending on the construction, they can retain from 75kJ up to over 8000 kJ of dynamic preassure. The rockfall barriers can be combined with avalanche protection measures. These rockfall barriers were introduced in Slovenija in larger scale in 1993. Since then over 2000 running meters of these up to date protective structures have been made. All the structures are generally raised on critical, difficult to access points above road sections at risk, which are subjected to a permanent rockfall hazard.

Fig. 5, 6: Rockfall barriers on slopes Mežakla (2003) and above state road next to Col settlement (2006)

3 ROCKFALL PROTECTION ON SLOVENIAN RAIL NETWORK

3.1 PARAMOUNT SLOVENIAN TEST BED Slovenian partners in PARAmount project, PUH and UL FGG, have been cooperated with (with status of official observer in project) with intention to prepare expert and practical oriented recommendations to contribute to greater safety and economy in the Slovenian , especially in the area of development, modernization and infrastructure management regarding protection against natural hazards. Bohinjska Railway was chosen for analyse on regional level. More detailed surveys were executed on the most problematic 20 km section between Podbrdo and Baška in the very narrow valley with very steep slopes above and below the railway. Even it is not the main track, (it is categorised as regional track) has ca. 350 000 passengers per year (mostly daily commuter (job, school)) and ca. 400.000 t transport of cargo per year. Decision about level of safety is very important. 6

3.2 HAZARD & RISK MAPPING The main challenges in PARAmount project were hazard/risk assessment and evaluating of the efficiently of existing protection structures and early warning systems and proposing the improved concepts of risk management. Existing Slovene legislation do not satisfactorily tackle the problems that rockfall hazard pose to the traffic (road, railway) infrastructure. Because of this, Slovene partners used in PARAmount project some procedures defined in the Slovene flood risk management regulation, prepared as result of the adaptation of legislation for implementation of EU Floods directive (Directive 2007760/EC) as the basis for the rockfall hazard/risk evaluation. The provisions of the directive were transposed into national law by adoption of amendments to the Water Act and new implementing regulations: the most important - Rules on methodology to define flood-risk areas and erosion areas connected to floods and connections of classification of plots into risk classes (Official Gazette RS, No. 60/2007). Hazard assessment highlights: Based on DEM and past events data; the latter exist for the whole Slovene rail network; high precision (10 meters stretches); enhanced with 1D and 2D numerical modelling; danger zones set by the Slovenian railways ltd. considered. Hazard map gives a good overview of hazard zones for the test bed to be used by the railroad management and commuters. Risk assessment highlights: high precision (10 meters stretches), a simple procedure, when hazard and vulnerability are known; applicable to the whole rail-network. Risk map gives a good overview of risk for the test bed to be used by the railroad management and commuters; sets priorities for risk management and reduction; can easily be applied to the whole rail network. Slovenian PARAmount's partners have, among others developed following tools:  Rockfall hazard map for Baška grapa test bed  Damage potential cadastre with a vulnerability map for Baška grapa test bed  Rockfall risk map for Baška grapa test bed Figure 7 and Figure 8: Rockfall hazard & Risk map of the rockfall hotspot in the Baška grapa test bed The using of modern calculation / simulation, combined with detailed studies carried out in those points that the modelling at regional scale has mapped as the most critical, can lead to an improvement of current techniques of risk assessment and hazard. Good praxis examples of technology and protection solutions from other countries significant contribute to acteptance of accelerating of development and increasing of investment in the field of natural hazard protection. Slika 1:

3.3 ROCKFALL PROTECTION CONCEPTS & MEASURES Regarding general protection concept agains rockfall and snow avalanches, investigated in the project, exist significant difference between road and railway infrastructure. In protection of road against rockfall hazard in last 15-20 years dominated manly modern flexible and certificated rockfall protection barriers. The slovene railway is from this point of view on the beginning. At the railways are dominated system for early warning and alerting called EAN or NOJP and rigid catching wooden-fences and simple light rigid mesh-fences. Many of these measures are loosing partially or completely their efficiency and functionality after an occured impact or because of lacking maintenance work. Regarding rockfall hazard, the Slovenian railway ltd., which is the manager of all public railroad infrastructure, has 7 gathered information on rockfall events in the past. On the basis of the gathered information a rockfall hazard

assessment in form of endangered railroad stretches was made and is used by the . For large railway accidents, a contingency plan made on state level is in use. In case of major railway accidents, the Administration for civil protection and disaster relief is responsible for managing rescue and relief operations in which local operational units (municipal civil protection, local fire brigades etc.) play a major role. Disaster relief operations are coordinated according to an existing contingency plan. Prevention and operational notification and warning on risks posed by natural and other disasters is prepared by National Notification Center in cooperation with the Environmental Agency of the Republic of Slovenia. It particularly deals with warning with regard to extensive rain and floods, extensive snow falls, snow avalanches, strong winds, sleet, high tides, thunderstorms with hail and announcement of risk of fire in the natural environment. They are also accessible on the web addresses: www.sos112.si/ and www.arso.gov.si/vode/opozorila. Influence of such a warnings on railway transport is very limited. Train usualy stoped only when something (event) alredy happend. In Slovenia almost all railway infrastructure is public and consists of 897.7 km of single track lines and 330.9 km of double track lines. According to the Railway Transport Act rock-fall and avalanche protection objects are also a part of the railway infrastructure. The Slovene railways ltd. (Slovenske železnice d.o.o.) is responsible for management and maintenance of all railway infrastructure and thus plays a major role in assuring natural hazard protection, including rock-fall and avalanche protection. The company’s involvement in natural hazard management includes maintaining protective structures, warning, closing railway sections for traffic when hazard is too high and also repairing caused damage. Owners of protective forests are obliged to respect certain rules regarding forest use and exploitation and thus contributing to lower hazard. On Slovenia rail network there are till now very few certified flexible rockfall protection barriers, only predominantly wooden rigid structures (Figure 3) and rigid light catch mesh fences.

Figure 9, 10: Very old typical wooden rigid rockfall protection structure (foto: J. Papež) On the most endangered 14 section there are installed early warning system called EAN in the length (sum) of 11.654 m (Figure 4). They exist also plans for additional 10.540 m of EAN.

Figure 11, 12: System for early warning and alerting, called EAN, in case of rockfall (foto: J. Papež) The main challenges of the further development are evaluating of the efficiently of existing protection structures and early warning systems and implementing of the new concepts of risk management with more intensive investment in maintenance and instaling of new certificated protection barriers. The available funds will never be sufficient for all necessary investments. Therefore railway should have the transparent overview on hazard and risk situation to set right priorities and to be aware and prepare on remaining residual risk. Paramount results are good basis for further actions. 8

Figure 13, 14: High-tech protection barrier above the railway Podbrdo-Bača, instaled 2013 (foto: J. Papež) 4. CONCLUSIONS

Practical cases presented in this article prove that up to date rockfall control measures can successfully substitute older measures. It has to be noted however, at least in the case of rockfall barrier, that these structures can serve their purpose only when they are regularly checked, cleaned and maintained. Expert has to help by decision: Primary or Secondary protection measures? Active or pasive measures? Primary protection is carried out on the areas where rockfall phenomena occur. Secondary protection is used when rocks have already been released. Where is possible is more adequat to stabilize slopes on the source area (primary), but based on preliminary assessment of the slope conditions will prevail definitely secondary measures. Today’s up to date rockfall barriers can retain falling rocks and boulders from 75 kJ up to over 8000 kJ of dynamic preassure. The rockfall barriers can be combined with avalanche protection measures. By the application of sound engineering principles to a predictable range of parameters and by the implementation of correctly designed protection measures in identified risk areas the exposure of injury and loss of property can be reduced substantially. These structures (rockfall barriers) can serve their purpose only when they are regularly inspected/checked, cleaned and maintained. Only on such a way cold assure the desired protection level. Provision must be taken to mitigate the residual risk. By decision of repairing and installing new so called “light semi-rigid net’s fences” without knowing baring capacity and certificate has to be solved transparent explanation, what is the purpose of such a measures. It is obviously, that could railway maintenance team with such a approach in period with very limited available founds cover larger endangered sections of railway with minimum protection / with limited functionality. This actions has to be accompanied by hazard assessment, which will show remaining/residual risk and with settled goals, plans, how will be in the future adequate solved the most critical sections on such a track. We must not allow ourselves, to be satisfied with minimum protection – we have to plan optimum protection and in the middle time raised awareness about residual risk and implement all measures to minimize the damage effects, if this hazard will realize. Railway’s management team has to take as short termed (urgency interventions) decisions as midle termed interventions (priority list of intervention/protection works). They need expert support (defining the hazard level) and suggestions (up-do date advisable set of mitigation measures) from competent institutions/companies, which could provide the technical part of the set of decisions. Slovenian Railwas has to continue to pursue and strength the development of integral system of protection against natural hazards. This has to be visible in planning much more founds for this field of activities. We should not overlook also the fact, that even with all the newest and most effective rockfall protection measures, the traffic safety is basically determined with its line and adequate vegetative protection of the slopes above. A complete protection against natural disasters does not exist. There is always some risk which has to be assumed by society and the individual and this is why the notification, awareness raising and education of the public regarding danger and threat and the possibilities for self-protection are so very important. The specific condition of railway transport demands special handling with residual risk. 9