Praktijkproef geluidsbakens bij ontruiming tunnel in dichte rook [Sound beacons for evacuation tested in a tunnel in dense smoke]

Purpose: Escape from a burning tunnel in dense smoke: Can that be done when sound beacons over the emergency exits assist people in escaping? A concept developed and tested in the UK claims 90% success but when we tested the beacons in a tunnel in The Netherlands without telling the participants about beacons over the exits, the success was a meagre 20%-"unacceptable" according to the Centre for Tunnel Safety of the Civil Engineering Division of the Directorate-General for Public Works and Water Management. Thereupon, TNO designed a self-explaining sound (dinner bell and the text "exit here") and obtained a success rate of 90% in a laboratory test. Will the new beacons be a similar success in a real road tunnel? Because a few participants had difficulty with the English, we used this time an English-Dutch text.
Methods: Insofar as possible we replicated the earlier road tunnel tests (report TM-03-C051). 75 Participants were transported by bus right into the middle of a road tunnel (the C-tube of the Benelux tunnel near Rotterdam) that was filled with dense smoke (visibility down to 1-2 m). They stepped on the roadway one by one with fixed intervals with the instruction to find safety and to get out of the smoke. This time again no advance instructions whatsoever were given about the emergency exits or the sound beacons.
Results: Eighty-five percent went straight to nearest emergency exit; one participant to the next nearest exit, in all a success of 87%. In these tense conditions participants had to leave the "safe" wall and to cross the roadway to get to the emergency exits. We saw that the sound indeed persuaded them to cross the roadway.
Conclusions: The new TNO sound is suitable for road tunnels, also when visibility is not yet gone. In that situation, the new sound beacons will be the signal to set tunnel evacuation in motion.