It is in all our interest to reduce the risk and provide a high level of safety to tunnel users. Swiss guidelines ASTRA 19004 and 89005 define a quantitative assessment methodology that describes the role of risk analysis in decision making and the evaluation of measures to achieve a higher safety in tunnels of the national roadway system. This methodology has been implemented in LoRis, an internally developed tool that facilitates the investigation of risk and provides information about cost-effective measures for existing as well as new tunnels.
LoRis is built on a Bayesian network, a probabilistic model, that computes the individual risk and relevant FN curves for fatalities and injuries. The underlying scientific approach takes quantitative information regarding events, and processes consequences using mathematical functions and CFD-simulations. The methodology is applicable to tunnels with a length greater than 300 m, open to the transit of normal, heavy goods and dangerous goods vehicles.
The tool is in continuous development, following the statistical trend of base rates, ready to employ the newest principles and perspectives of the roadway research community.