Following signature of a Memorandum of Understanding in May 2001, Infraspeed BV  in December 2001 signed a contract with the Ministry of Transport, Public Works and  Water Management and the Ministry of Finance of the Netherlands for provision and  maintenance of the superstructure of the new high-speed rail link between  Amsterdam and the Belgian border (the HSL Zuid Line).  Each of the industrial sponsors which form Infraspeed will bring to the project its  extensive experience in developing and managing rail projects. Siemens will be  responsible for the delivery of the power supply system, the ETCS (European Train  Control System) signalling system, the GSM-R communication systems and the  ancillary equipment. BAM NBM will supply the track system and the noise barriers  and Fluor will provide project management. The HSL Zuid line will be available on  the Rotterdam to Antwerp route by mid 2006 and on the Amsterdam/Schiphol to  Rotterdam route by the end of 2006. The total route length is 100 kilometres.  Incorporated in the line are several tunnels. The simple fact that tunnels are under-  ground, has major consequences for the accessibility of any incident location inside  the tunnel. Because of this many emergency provisions in the tunnel are aimed at  enabling passengers to seek safety independently before the arrival of rescue  workers. For example, the ventilation system in the tunnel directs smoke away from  the accident site. In addition the tunnel is equipped with several other emergency  systems like a fire fighter system which includes a wet pipe fire water supply. The  design of the fire fighter system takes into account availability under all weather  conditions. One of the requirements is sufficient protection against frost for the wet  pipe fire water supply. Under this requirement it is assumed that the average air  temperature inside the tunnel will be -10ºC when the outside air temperature is -  20ºC. The question has risen whether this assumption is still valid in case every 6  minutes a train passes through a tunnel tube. It can be expected that with each train  passage air from outside will be supplied which could lower the tunnel air temperature.  FlowMotion has been consulted by Infraspeed to investigate the air flow inside the tunnel during the interval in which a  train passes through one of the HSL Zuid tunnels. For this purpose a dynamic CFD model (Computational Fluid  Dynamics) has been developed which not only takes into account the high speed of the train (over 80 m/s) which leads  to compressibility effects, but also contains sufficient geometric details of the tunnel to account for the effect of air  shafts and pressure relief openings in the tunnel. The simulations have been able to show that a train passage creates  considerable air movement through a tunnel, which continues until the next train arrives. As expected this air  movement causes fresh air to flow into the tunnel through the tunnel entries and the air shafts.  Offices: The Netherlands Leeghwaterstraat 21 2628 CA Delft Tel.: +31 15 278 2907 Germany Weenermoorer Str. 193 26826 Weener Tel.: +49 4953 922 969 Consultancy for Heat Transfer and Fluid Dynamics CFD makes fluid dynamics visible. We solve every Flow problem. No ice in the train tunnel Influence of a train in a tunnel on the ventilation system InfraSpeed www.infraspeed.nl velocity temperature