The conditions during a fire in a tunnel can become very severe due to flames and dense smoke. The rescue service may have difficulties to find tunnel occupants in need of assistance. IR cameras are often used to find occupants, but they have limitations. It maybe very problematic to bypass or see through flames with IR cameras. Therefore, it is of interest to develop other methods that may solve the problem of optically seeing through flames.
Fire tests were performed where the ability of different systems to register a target(blasted aluminium bucket) behind a fire was evaluated. During the measurements three different types of optical instruments were added to the test set-up: 1) a system for gated viewing (GV), Aqua Lynx, 2) a 3D laser scanner, ILRIS-3D (ILRIS), and 3) a thermovision camera (THV), ThermaCam® SC2000. A DV camera was also used forvisual documentation.
The tests show that the gated viewing system had problems registering the target whenthe smoke became dense. Some improvement could be made by optimising the setting of detector parameters, etc. However, the gated viewing system needs to be set to a specific distance which is a limitation.
The 3D laser radar (scanner) proved to be able to see through smoke, provided it was not too dense, and flames and was in that sense better at detecting the target than both the thermal vision system and the visual technique of the DV camera. This means that this system should have the ability to help the rescue services in situation where the IRcameras or visual aids have limitations.