Analysis of air consumption and moving speed by firefighters during full-scale search & rescue experiments in a tunnel

Abstract

Experiments were carried out in a 420 m long dead-end tunnel to assess air consumption and movement speed. The operation consisted of a 417 m walk to locate and rescue a victim. Seven teams of 5 blindfolded firefighters were sent into the tunnel with a single-bottle SCBA, a stretcher and a mobility cane. 14 firefighters (i.e., 44%) had to use ‘reserve air’. Hence it is not considered safe to carry out such an operation. However, all the crews noticed the sign that they used half of the available air in their bottle, so it is possible to start the S&R operation in a tunnel and safely return at the 175 bar mark. The average time to completion was 35.2 minutes. All crews became better at using the cane, leading to a higher average movement speed (0.50 m/s) out of the tunnel than into the tunnel (0.39 m/s). The average air consumption per walking meter was 2.20 L/m going in and 1.33 L/m going out. The average air consumption rate was 49.9L/min going into the tunnel and 38.9 L/min going out of the tunnel. It is shown that speed plays an important role. Faster firefighters have a lower total air consumption.