Author(s)

M. Holický

Abstract

Probabilistic methods of risk optimization are applied to identify the most effective safety measures applied to road tunnels. The total consequences of alternative tunnel arrangements are assessed using Bayesian networks supplemented by decision and utility nodes. It is shown that the probabilistic optimization based on the comparison of societal and economic consequences may provide valuable information enabling a rational decision concerning effective safety measures. A general procedure is illustrated by the optimization of a number of escape routes. It appears that the discount rate and specified life time of a tunnel affect the total consequences and the optimum arrangements of the tunnels more significantly than the number of escape routes. The optimum number of escape routes is also significantly dependent on the ratio of cost of one escape routes and acceptable expenses for averting a fatality. Further investigation of relevant input data including societal and economic consequences of various hazard scenarios is needed. Keywords: tunnels, escape routes, risk optimization, Bayesian network. 1 Introduction Tunnel structures usually represent complex technical systems that may be exposed to hazard situations leading to unfavorable events with serious consequences. Minimum safety requirements for tunnels in the trans-European road network are provided in the Directive of the European Parliament and of the Council 2004/54/ES [1]. The Directive also gives general recommendations concerning risk management, risk assessment and analysis. Methods of risk assessment and analysis are more and more frequently applied in various technical systems (Melchers [2], Stewart and Melchers [3] including road tunnels (Holický and Šajtar [4]). This is a consequence of recent tragic events in various tunnels and of an increasing effort to take into account

Keywords

tunnels, escape routes, risk optimization, Bayesian network.