A tunnel is essentially a passage created through surrounding soil or water, totally
enclosed except for the entrance and exit. With the increase in vehicular traffic,
urban planning is increasingly using tunnels for traffic movement since they reduce
travel time, and clear surface vehicles from long distance roads. Due to the nature of
tunnels being entirely enclosed for the length of the distance, air pollution within can
become highly concentrated. Gases like carbon dioxide, nitric oxide and nitrogen
dioxide released from vehicular traffic, and fine particulate matter can cause health
hazards ranging from respiratory problems to heart issues. Fine particles, when
gathered in dense concentrations, can also reduce visibility considerably presenting
a significant driving hazard.
Ventilation in tunnels is a therefore critical need for safety and comfort of users. It
ensures proper air quality and control, reduces air temperature and controls smoke
in the event of a fire. However, costs of operating a tunnel ventilation system can be
quite high. A reliable tunnel atmosphere monitoring system continuously measures
concentration of gases in the tunnel and monitors visibility, triggering the ventilation
systems into action only when needed to clear pollution.
Tunnel monitoring systems help monitor critical parameters like
- Air flow
- Carbon monoxide
- Nitric oxide
- Nitrogen dioxide
- Wind speed and wind direction
- Light intensity
Various technologies available for tunnel monitoring include infrared, ultrasonic,
luminance, illuminance and electrochemical cell technology.
Codel International, a Forbes Marshall company based in the UK, offers a wide
range of tunnel monitoring solutions. Available as stand-alone sensors or integrated
into a network system, these sensors are installed in over 350 road and rail tunnels
worldwide. Read more about our solutions here . The chart below gives an overview.