Proceedings:
6th International Conference on Tunnel Safety and Ventilation
Publication Date:
Apr 2012
Authors:
Conrad Stacey
In new road, rail or bus tunnels in Australasia, a variety of factors has caused a ratcheting-up of fire safety provisions, often leading to every conceivable measure being included at the project conception stage and not critically questioned at later stages. The ‘FEB Process’ is then often a charade in which we (the project) pretend, via the “”process””, that we don’t know by inspection that the tunnel is safe enough and we (fire engineers) spend a lot of time on sometimes questionable analysis to ‘test the trial design’ before concluding it is OK.
If there is wasted expenditure in any over-provisioning, it is hidden by the massive civil costs of tunnelling. In a refurbishment, the mechanical and electrical plant is closer to 100% of the project cost, and so there is more focus on justifying the fire safety design and its cost. There is also generally a contractual framework which facilitates such questioning. Consequently, the decisions for tunnel refurbishment projects can be very different, particular in tunnels which have a very high access cost because they are already in heavy use.
We also know that, for most modern tunnels, the absolute risk cannot justify half the gear we put into them, yet the community has a heightened perception of the risk and an understandable aversion to major incidents or entrapment, however low the probability. Those responsible for the judgments on risk and expenditure have a difficult task. This paper discusses the flaws inherent in the common fire engineering approaches to tunnel fire safety and seeks to offer a new simpler perspective for the governance and project decision making around the provisions to be included in a refurbishment design. The thoughts offered may be useful in getting to the right answer for project teams, giving context for a clear justifiable decision basis in the project’s format.