Quantitative Risk Assessment Model for Dangerous Goods Transport through Road Tunnels

A Quantitative Risk Assessment Model (QRAM) to evaluate the risks of dangerous goods transport through road tunnels was developed jointly by PIARC and OECD as part of the ERS2 project (1997-2001).

Since then, the software has been applied to a wide range of tunnels in several countries.

What does the QRA model do?

The software allows users to:

  • compare the risks due to dangerous goods transport along alternative routes; for example, via the tunnel or an alternative open route
  • evaluate issues associated with tunnel regulations; for example, the QRAM can be used to support the decision to choose the most relevant of the proposed ADR dangerous goods groupings for each specific road tunnel
  • compare the risks along a route with acceptability criteria for individual and societal risks
  • evaluate tunnel equipment options; for example, the QRAM can be used to compare the effects of changing the spacing between emergency exits.

The software can be used to perform a risk analysis as required for dangerous goods transport by the European Directive 2004/54/EC on minimum safety requirements for tunnels in the trans-European road network.


  • Contour maps of individual risk along tunnel and open routes
  • Societal risk presented as FN-curves, where F is the frequency of N or more fatalities (and/or injuries)

Presentation of the QRA model

The QRAM software is based on Microsoft Excel.

There is a wide range of information that has to be gathered and prepared in order to run the QRAM. Notably, the user has to enter data to describe:

  • routes, defined in sections;
  • tunnel geometry (length, cross-section and vertical alignment), ventilation (specialist help may be required for complex tunnels), drainage, and emergency escape measures (warning systems, spacing of exits);
  • traffic characteristics, including vehicle mix and traffic speeds, defined for each route section and traffic direction;
  • population along the route.

Input screens help to guide the user through the process of entering this data and running cases.

The QRAM considers 13 accident scenarios which are representative of key dangerous goods groupings.

  1. Heavy Goods Vehicle fire with no dangerous goods (20 MW)
  2. Heavy Goods Vehicle fire with no dangerous goods (100 MW)
  3. Boiling Liquid Expanding Vapour Explosion (BLEVE) of Liquid Petroleum Gas (LPG) in cylinders
  4. Pool fire of motor spirit in bulk
  5. Vapour Cloud Explosion (VCE) of motor spirit in bulk
  6. Release of chlorine in bulk
  7. BLEVE of LPG in bulk
  8. VCE of LPG in bulk
  9. Torch fire of LPG in bulk
  10. Release of ammonia in bulk
  11. Release of acrolein in bulk
  12. Release of acrolein in cylinders
  13. BLEVE of carbon dioxide in bulk (not including toxic effects)

The QRAM takes into account:

  • accident frequencies (derived from historical datasets);
  • physical consequences of incidents within tunnel(s) and along the open routes;
  • escape and sheltering effects;
  • effects of hazards (such as heat and smoke) on people.

The results for different routes and traffic are calculated in terms of Societal Risk. This reflects the range of possible outcomes of an accident, each with different probabilities. There might be a low chance of injuring most of the people in a town, or a higher chance of injuring just a few of them.

This relationship is illustrated by an 'F/N curve', where F is the frequency of N or more fatalities (and/or injuries). An example set of F/N curves is shown here. Each curve can also be evaluated in terms of a single value representing the average number of fatalities per year, called the Expected Value (EV).

The F-N curves can be produced for fatalities and/or injuries, and for road users and/or the local population.

Ruffin E, Cassini P and Knoflacher H.
Transport of hazardous goods.
See chapter 17 of Beard A and Carvel R (2005).
The Handbook of Tunnel Fire Safety. Thomas Telford Ltd, London, 2005.

Knoflacher H and Pfaffenbichler P C.
A comparative risk analysis for selected Austrian tunnels.
2nd International Conference Tunnel Safety and Ventilation, Graz, 2004.

Powerpoint presentation,
XXIInd PIARC World Road Congress,
Durban, South Africa, 19-25 October 2003.

Knoflacher H, Pfaffenbichler P C and Nussbaumer H.
Quantitative Risk Assessment of Heavy Goods Vehicle Transport through Tunnels - the Tauerntunnel Case Study. 1st International Conference Tunnel Safety and Ventilation, Graz, 8-10 April 2002.

Knoflacher H and Pfaffenbichler P.
A quantitative risk assessment model for road transport of dangerous goods. Proceedings of the 80th Annual Meeting of the Transportation Research Board, WashingtonDC, USA, 7-11 January 2001.

OECD. Safety in Tunnels - Transport of dangerous goods through road tunnels. 2001.

Saccomanno F and Haastrup P. Influence of Safety Measures on the Risks of Transporting Dangerous Goods through Road Tunnels. Journal of Risk Analysis, 2000.

Lacroix D, Cassini P, Hall R and Saccomanno F. Transport of dangerous goods through road tunnels: an integrated QRA Model developed under the joint OECD/PIARC Project ERS2. International ESReDA Seminar on'Safety and Reliability in Transport', Oslo, 19-21 May 1999.

Users support and training

No support is currently available (more details in the future).