In a bypass installation, polluted air is forced through a crescent-shaped side tunnel containing precipitation equipment. The system used in Norway's Granfoss, Ekeberg, Lardalstunnel and Chinbu Tunnel in South Korea.
Advantages of CTA's bypass system compared to other bypass systems:
In ceiling-mounted installations fans and filtration equipment are mounted at intervals overhead. This system has been installed by CTA in Norway's Hell Tunnel (Trondheim), Nygårdstunnel (Bergen) and Strømsåstunnel (Drammen).
Norway's Hell Tunnel (Trondheim), Nygårdstunnel (Bergen) ； Strømsåstunnel (Drammen).
Advantages of Ceiling-mounted compared to Bypass:
The ventilation shaft filter system was installed in Festning tunnel, Oslo, Norway. In this application 3 fans are able to move over 200.000m3/hr of cleaned air from the tunnel through a ventilation shaft. The air is cleaned to protect the local population from the heavy pollution cause by traffic using the busiest tunnel in Norway. CO monitors automatically start the system and visibility monitors in the tunnel.
Distributed Ceiling Mounted
Sometime distributed ceiling mounted air cleaners are installed for the limited space tunnel, especially for the existing tunnel needing air pollution control.