Road tunnels have to be supplied with sufficient fresh air during operation. Depending on the fleet segmentation (percentage of trucks/cars, diesel fuled engines, pollutant classes, etc.) and various other secondary conditions, different lead components for controlling the supply of fresh air can arise. Today, for example, the CO concentration is not anymore the lead component for ventilation control (except in tunnels in very high-altitude mountainous terrain). During the last decade visibility has taken over this role and nowadays NO2 (not NO, due to the strongly fluctuating proportion of primary NO2s) becomes increasingly more significant and is already the lead component for ventilation control in many modern tunnels.The complete range of products from SICK for measuring devices that are developed and built for the dedicated use in tunnels embraces the measurement of all gas components typically measured in tunnels and corresponding measurement principles and emphasizes SICK's leadership in both the technology and market in this field.
Tunnel fires rank among the most fearsome occurrences in road and rail traffic. In more and more studies, something has been substantiated that experts have known about or had an inkling of for a long time – namely, that the optical measurement of smoke density is the quickest and generally most reliable way to detect fires early. Only approx. 10 to 15 minutes are available for self-rescue in the event a vehicle fire has not been extinguished. Along with the quick detection of a fire – e.g. with a SICK optical smoke detector – it is also very important that the distribution of smoke is recognized and to ensure best possible stratification of smoke on the tunnel ceiling. To this end, it is essential that for exact information on the flow velocity, measurements are taken over the entire width of the tunnel (e.g. with FLOWSIC200) and not only at a single point.