New methods for road tunnel fire safety evaluation and upgrading

Abstract

A new tunnel fire safety evaluation and upgrading procedure was developed to replace the current seriously flawed ‘additive’ methodology. Such a procedure is necessary given the number of recent tunnel fires with serious consequences to human life, structure and the wider socio-economy. The procedure takes a holistic integrated approach and follows a critical path. The new methodology, called Upgrade, was tested for a hypothetical ‘basic’ example tunnel and showed its ability and flexibility in providing the risks and economic impacts for different upgrading options singly and in combination. The assessment shows clearly that it is not just safety features that are critical to results but also items such as the location of the fire and its size. The model is also applied to a ‘real’ alpine tunnel case to demonstrate that the smoke extraction system would have been justified by the holistic upgrading procedure. Both the development of Upgrade and the appraisal of socio-economic impact are key innovations of this work. Tunnel closure times were found to have a marked, even dominant, influence on human safety and especially the socio-economic impact. Closure times should therefore be reduced to a minimum by judicial selection of a combination of safety features that require night closures or part closure coupled with a reduced overall time for upgrading work. The work was carried out as part of the Uptun (Upgrading tunnels) 5th framework European Union (EU) project. The results of this work are aimed at assisting the EU develop a directive for road tunnel safety.