Jens Chr. Bennetsen

Head of Center of Excellence for Advanced Simulations

T: +45 5161 6475

Building a high-speed railway station inside a mountain

Building fourteen-kilometer double rail tracks – including a station – inside a mountain is quite the task. Still, that was exactly the challenge facing the team behind the Norwegian mountain station, Holmestrand. 

Trains passing through Holmestrand station can reach speeds as high as 150 km/h and in the original design, the wind pressure at the station’s access tunnel would reach 15 meters per second. In short, the passengers would, quite literally, have been blown away.

This challenge was discovered by using Computational Fluid Dynamics (CFD) to simulate and visualise the design plans. 

Determine how things operate – without having to build them 

CFD is a computer-based 3D technology used to calculate flows in liquids and air. The method enables precise calculations of a given design, detailed insight and data that can ultimately save both time and money. By testing designs before starting the construction process, it is possible to avoid unpleasant surprises further down the line. 

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“CFD determines how physical things operate without anyone having to build them. Just as meteorologists can predict the weather, we can use CFD to predict how the wind will blow, how smoke will move and what happens when a train passes into and out of a tunnel.,” explains Jens Christian Bennetsen, who has worked with CFD simulation for more than 20 years. 

CFD technology makes it possible to accurately evaluate the design and optimize it, to make it more cost-efficient. CFD can benefit a wide range of projects, and has been utilized on everything from urban planning, fire safety optimisation and ventilation in building interiors to baseball stadium design and railway projects. 

In the case of Holmestrand Station, CFD simulation made the station safe for passengers and prevented unnecessary costs after commissioning, because the design requires less adaptation than usual., at the same time.

Based on the CFD calculations, the access tunnel at the station was enclosed by a wind-proof lock with two doors at each end. This made the station free of wind pressure problems. A so-called Pressure-relief-tunnel is another measure, intended to make sure that people on the platform do not experience an uncomfortable pressure each time trains are passing.

Hollowing mountains