Optimization of Societal Risk in Tunnels Outline of the presentation Directives on minimum safety Risk analysis using BBN Societal risk optimization A case study Conclusions Milan Holický, CTU in Prague

Tunnels in the city ring in Prague Motivated by the Directive 2004/54/EC of the European Parliament and of the Council of 29 April 2004 on minimum safety requirements for tunnels in the trans-European road network. Official Journal of the European Union L 201/56 of 7 June A case of a route tunnel, length 4000 m, two tubes, each with two traffic lanes, DGV, HGV and Cars, optimization of escape routes, initially 1000 m.

Bayessian network for a tunnel of 4000 m

Sub-model for DGV

Criterion of societal risks FN diagram 1,0E-08 1,0E-07 1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01 1,0E+00 Number of fatalities N (1, 10, 100, 1000) P(R > N)

Expected number of fatalities per year k N(k)

Optimization principles C tot (k,p,n) = N(k) R 1 Q(p,n)+ C 0 + k C 1 The total consequences The standardized total consequences The cost ratio R 1 expenses for averting a fatality based on the Life Quality Index – LQI, C 1 cost of one escape route The discount coefficient The necessary condition for the minimum

Standardized consequences Variation of the standardized total consequences  (k,p,n) with k for selected p, cost ratio  = C 1 /R 1 = 1, the life time n = 50 and 100 years n = 50 yearsn = 100 years

Variation of  with k and  Variation of the standardized total consequences  (k,p,n) with the number of escape routes k for selected cost ratios , the discount rate p= 0,03 and the life time n = 100 years

Variation of  with k and  Variation of the standardized total consequences  (k,p,n) with the number of escape routes k and cost ratios , the discount rate p= 0,03 and for the life time n = 100 years

Variation of  with k and p Variation of the standardized total consequences  (k,p,n) with the number of escape routes k and the discount rate p for cost ratios  = 1 and for the life time n = 100 years

Concluding remarks Optimization of societal risk provide valuable information enabling specification of risk criteria and a rational decision concerning effective safety measures applied to road tunnels. The optimum number of escape routes depends on the ratio of the cost of one escape route and expenses for averting a fatality. LQI seems to be a promising concept for determining expenses for averting a fatality. Bayesian networks supplemented by decision and utility nodes provide effective tools for the risk analysis and optimization. The discount rate and assumed life time may considerably affect the total consequences and the optimum arrangements of the tunnels. Further investigations of relevant input data concerning conditional probabilities describing individual hazard scenarios and models for their societal and economic consequences are needed.

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Risk Management Risk control Risk management Risk assessment Risk analysis Risk evaluation Decision - making Monitoring Hazard identification Risk estimation Risk acceptance Option analysis Risk communication ISO, CIB, JCSS, PIARC ISO TC98/SC2/WG11 General Principles on Risk Assessment for Structures

Flow chart of risk assessment ISO, CIB, JCSS, PIARC ISO TC98/SC2/WG11: General Principles on Risk Assessment for Structures

Povltavská Parts of the routes intended for civil defence Cross section Barrandov bridge Břevnov radial Radlice radial West part of city circle in Prague

Portal of the Strahov tunnel