The Austrian Tunnel Risk Model

A performance-based approach

Since the implementation of the EC Directive 2004/54/EC, tunnel safety has become a very important issue in designing and operating road tunnels. Austria introduced a performance-based approach to road tunnel safety. In its first publication, the Austrian Tunnel Risk Model (TuRisMo) described one of the first methods for analysing and evaluating road tunnel safety in a quantitative manner.

TuRisMo combines a set of different methodical elements to analyse a tunnel system in its entirety, taking an integrated approach, and allows calculating the expected societal risk value for tunnel users in the investigated tunnel.

The method consists of two main elements: a quantitative frequency analysis and a quantitative consequence analysis.

Frequency analysis – collisions and fires

To identify a set of characteristic incident scenarios (collisions and fires) and to calculate their frequencies, an event tree analysis is made.

Consequence analysis – collision

To estimate the damage resulting from possible collisions, the method provides default values for individual collision scenarios, which were derived from statistical data obtained from historical tunnel collisions.

Consequence analysis – fire

To estimate the damage resulting from fires, the method provides default values for different fire scenarios, which were calculated on the basis of detailed smoke propagation and evacuation simulations.

Continuously upgraded

Since the publication of the model in 2008, comprehensive practical experience has been gained. TuRisMo was continuously upgraded to meet the multifaceted requirements of different tunnel systems. Thus, the model now permits a much more detailed investigation of the factors influencing fire risk and a much wider range of applications.

Well-suited to perform all kinds of risk-based studies for

  • selecting the best design alternative or combination of risk mitigation measures available to minimise risk
  • identifying the most cost-efficient solution to fulfil the minimum safety requirements
  • quantifying the effects of specific shortcomings on risks in existing tunnels (e.g. on the ventilation system)
  • quantifying the effects of potential compensation measures on the risks and identifying the most cost-efficient combination of compensation measures

A joint effort by Austrian authorities, associations and private companies

In April 2015, the upgraded model was published in a revised issue of the Austrian RVS 09.03.11 guideline. In Austria, guidelines for road tunnels are drawn up by the Austrian Association for Research on Road, Rail and Transport (FSV). Working groups have been established at association level, involving relevant stakeholders as well as experts from universities and professional practice.

The RVS 09.03.11 revision was a joint effort by the Austrian Federal Road Tunnel Authority, the Austrian Ministry for Transport, Innovation and Technology, Austria’s major motorway and tunnel operator ASFiNAG, the Austrian Federal Fire Brigade Association and experts from Graz University as well as from private companies. ILF Consulting Engineers Austria GmbH was commissioned to develop the core part of the model.