By-Pass Installation
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:
- Higher system efficiency
- Total installation costs are lower
- Lower operating costs
- Improved airflow characteristics
- Lower excavations costs: requires ca. 30% less rock volume to be removed
Ceiling-mounted Installation
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:
- Lower construction cost
- In the event of fire, exceptionally large heat and smoke evacuation capacity
- System tested with smoke at 200°C
- Higher efficiency in big tunnels
Shaft Installation
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.
- Without air cleaning, the air flow exit velocity should be more than 25m/s with shaft solution
- With air cleaning system, one-meter height is ok and airflow speed is 7-9 m/s.
- cost difference is depending on the tunnel height
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.
Advantage:
- Freedom to choose installation place and quantity
- Very compact size to fit limited ceiling space
- Can be installed in the existing opening tunnels
- Unique technology to get high removing efficiency under high air speed
