Simulation and measurement of road tunnel ventilation

Abstract A computer program forPC has been prepared to simplify studies of air flows in road tunnels and the related problem of pollution concentration due to emission from vehicles. Results from simulations include air pressures, flow rates, and pollution concentrations along the tunnel. Input data are tunnel geometry, including flow friction factors and loss coefficients, plus traffic and emission data and air pressures at boundaries. The program has been prepared in the IDA environment for modular simulation. All mathematical models have been formulated in the Neutral Model Format (NMF) [Sahlin 19941. The program has been validated by comparisons with older programs (Malmstrom 1980). Advantages of the new program, as compared to traditional programs, are its great flexibility, ease of maintenance, and extendibility, as well as the very moderate implementation time. It has proved to be a useful tool for studying alternative ventilation concepts for road tunnels. Air flow rates have been measured in part of the “Sodersledstunneln,” a much-used road tunnel in central Stockholm. The measurements were made with tracer gas technique, which made it possible to measure without disturbing the traffic flow through the tunnel. The measurements have been compared to simulations of the air flow.