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Wednesday, May 06, 2009

Short Review of 2nd International Tunnel Safety Forum, Lyon, April 2009

The 2nd International Tunnel Safety Forum for Road and Rail was held in Lyon, France on the 2oth and 21st April 2009. The conference was organised and sponsored by Tunnel Management International.

This conference marked (almost) the tenth anniversary of my first tunnel safety conference, which was the 1st Int Tunnel Fires Conference in May 1999, also held in Lyon and also organised by TMI. That conference fell two months after the fire in the Mont Blanc tunnel and was attended by about 300 delegates. This year's conference was attended by about 110 delegates.

The conference dealt with many topics relating to tunnel safety, split into the following themed sessions: "Standards", "Materials", "CFD", "Smoke & Modelling", "Operations", "Safety", "Fire", "Detection", "Evacuation" and "Extinguishing".

Presentations came from representatives from five continents (none from Africa) and highlighted differences between approaches to safety in different countries.

While the presentations returned to several of the well discussed topics in the field, such as "Critical Ventilation Velocity" - which has been discussed at every tunnel conference I've been at in the past decade - there were some new discussions. The two new modelling topics which were highlights of the conference were "Multi-Scale Modelling" (mentioned in three presentations) and CFD modelling of airflow which included a moving train.

Two of the most interesting presentations, neither of which is in the proceedings, were presented by Bob Allen from the Sydney Harbour Tunnel company. The first discussed fire tests using extraction and suppression systems in the tunnel (efficiency of smoke extraction is highly dependent on position of the fire relative to the extraction points), while the second presented the "Water Screen" stop signs (see picture) which are routinely used to tell overheight vehicles not to enter the tunnel, and may be used to close the tunnel in an emergency.

The two biggest debates amongst the delegates concerned the issue of 'design fires' for ventilation systems and the utility (or otherwise) of smoke exhaust systems. As is often the case at such conferences, the greatest number of papers were devoted to discussing ventilation strategies and designs for various tunnel projects.

I was also expecting a debate on the issue of sprinklers or water mist systems, yet this did not really come to the fore. The session on suppression came at the end of the conference, and many of the delegates were not keen for a big debate at the end.

I came away from the conference with the feeling that there is still plenty more work to be done, but also that we are at a bit of a turning point in tunnel safety practice. We may well have reached the point of highest complexity in tunnel safety systems. On the basis of what I heard at this conference, it wouldn't surprise me if we see a return to simpler safety systems over the next few years - less complex ventilation systems, conventional sprinklers rather than water mists, and systems designed for smaller 'design fires'. but only time will tell.

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