Combining diverse driving forces for smoke control in complex urban traffic link tunnels (UTLTs) using one-dimensional flow modelling

Urban traffic link tunnels (UTLTs) could become increasingly more complex because they incorporate both looped main tunnels and multiple branch tunnels. In such a complex tunnel structure, smoke control in the event of fire becomes more difficult than that in conventional simple tunnels due to the enhanced flow interactions among various branches. Moreover, there are still no specific smoke control guidelines for such complex tunnels. Furthermore, the use of a single smoke control method could be inapplicable or even unaffordable in UTLTs because the complicity of the configuration and the interaction between the flow of different branches. In this paper, hybrid ventilation modes which combine diverse flow driving forces are proposed for smoke control in UTLTs. The hybrid modes could exploit the advantages of each of the constitutive modes. Three-dimensional numerical simulations are performed to show the benefits of combining diverse driving forces. Then, a one-dimensional flow modelling approach was employed to investigate the efficiency of three hybrid modes. The results demonstrate that proper matching of various driving forces is crucial for effective application of the hybrid modes. This paper provides a new route for UTLT smoke control and also demonstrates the advantages of one-dimensional flow modelling in such designs.