STOREBAELT EASTERN RAILWAY TUNNEL: DANIA TUNNEL BORING MACHINE FIRE - ANALYSIS AND RECOVERY

On 11 June 1994, an uncontrollable fire broke out in the tunnel boring machine (TBM) Dania during the construction of the 8km long eastern railway tunnel of the Storebaelt (Great Belt) crossing in Denmark. There were no casualties. This paper discusses the analysis of the fire and its immediate findings, together with the subsequent recovery programme. Several inspections of the damage were made, and photographs and measurements were taken. There was no obvious damage to the TBM's main structural steel. A bulkhead was constructed immediately, to reduce flooding risks. Damage to the tunnel lining near the fire was assessed, and its remaining strength was estimated, together with the likely ground and water loads on the damaged segments. Four basic approaches to the recovery and repair of the tunnel were considered, and each given a cost-benefit analysis and safety investigation. The chosen method was to place a new lining within the existing lining, wherever structural integrity was doubtful. A phased programme of steps was established, with hazard prevention procedures to minimise risk. Further investigations and tests established the extent of the necessary repairs. Two fire tests were conducted on spare tunnel lining segments, to provide better data for use in tunnel operational risk analysis.