References

A word from a customer
Tunnels
2017Length(m)#Microphones
Arlberg tunnel15.516175
Southwick tunnel49010
Gleinalm tunnel, 1st tube8.436129
Wilten tunnel50913
Kollmann tunnel63316
Wald tunnel2.82665
Klaus-Spering tunnel4.902108
Dalaas tunnel1.81019
2016 Length(m)#Microphones
Oswaldiberg tunnel4.302119
Kroislerwald tunnel67919
Liefering tunnel50314
Flirsch tunnel1.12619
2015Length(m)#Microphones
Ehrentalerberg tunnel3.34575
Lendorf tunnel80020
Trettnig tunnel45012
Falkenberg tunnel1.09026
Bosruck tunnel5.505122
G├Âtschka tunnel4.43586
Pernau tunnel2454
Neumarkt tunnel1.97038
Lest tunnel54512
2010Length(m)#Microphones
Kirchdorf tunnel (pilot system)2.80749