Air flow measurements in the underground section of a UK light rail system

A series of air velocity and temperature measurements and thermal images were obtained from the underground section of the Tyne and Wear Metro system in the centre of Newcastle upon Tyne. The results indicated that the flow in the tunnels is dominated by a strong background flow that is independent of the train movement but that the flow structure in the main interchange station in the system was found to be very complicated with stratification and flow reversals being observed. The impact of the ventilation system on the natural air flow indicates a lack of understanding of subway climatology when the system was constructed. It is considered that a full and extensive monitoring of the entire subway system be undertaken over a prolonged period to facilitate a full understanding of the air flow and its interaction with the over ground climate. This will remove risk to passengers and emergency service personal in the event of the release of a toxic agent or the presence of a fire in the subway.