In two-tube road tunnels, the adjacent tube generally serves as a 'safe haven' for tunnel users fleeing from an incident. Access is through cross passages that are distributed over the tunnel length. The design and the underlying regulations for cross passages of road tunnels differ considerably from country to country.rnGenerally, it is understood that the cross passages have to be kept free from smoke and that a minimum inflow of fresh air has to be provided in order to prevent smoke from entering the escape tube through open doors. But if it comes to the technical details on how to achieve this goal, different approaches in various countries show a wide spectrum of solutions.rnThe paper focuses on cross passages in long two tube road tunnels and the problem of unfavourable pressure forces acting on escape doors.rnWhere national guidelines prescribe standard wing doors as escape doors, the design and control of the tunnel ventilation poses a considerable challenge. The balance of providing a minimum overpressure to guarantee fresh air supply and not to exceed the pressure limit for manageable door mechanisms is hard to achieve, sometimes leading to complicated layouts that might not prove robust in every possible case of a real incident.rnOn the basis of experience from road tunnel projects in several European countries, the authors give an overview over the different regulations and approaches and point out the difficulties that often occur. The pros and cons for using sliding doors are discussed as well as the need for independent pressurisation systems or passive pressure control devices.rnA calculation method is demonstrated and different control strategies for the road tunnel ventilation with regard to the conditions at the cross passage are discussed.
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