By Michael Rothenborg, May 2017
Had Holmestrand Station been completed according to its initial design, passengers would have literally been blown away. Trains passing through the Norwegian mountain where the station is located can reach speeds of over 150 km/h – meaning a wind pressure of 15 metres per second in the access tunnel, which makes it very difficult for someone to stand upright.
Ramboll discovered this using CFD as a planning tool. And this is just one of many examples of how this 3D technology can significantly benefit clients and society in general.
“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, Senior Project Manager at Ramboll Transport.
He has worked with CFD for over 20 years, initially on projects with building interiors where the technology helped to dimension ventilation systems and optimise fire safety. This gradually extended to other areas like urban planning in Hong Kong and baseball stadiums in the USA. For well over 10 years, the technology has been a fellow passenger on some of the most advanced railway and high-speed train projects in the Nordics.
A wind-proof station
“CFD determines how physical things operate without anyone having to build them,” explains Jens Christian Bennetsen.
“We can base the design on facts and optimise it to make it cheaper, while also more accurately taking into account security requirements from authorities, price requirements from operators and other factors. This also helps prevent unnecessary costs after commissioning because the design requires less adaptation than usual. This reduces the project risk.”
In Norway, Ramboll proposed enclosing Holmestrand station and the access tunnel with a wind-proof lock with two doors at each end. When the station opened to the public in November 2016, it was free of wind pressure problems. And the stakeholders were impressed:
“Never before have we built a station inside a mountain with trains running at such high speeds,” said Knut Edmund Knutsen, Project Manager at Jernbaneverket to the Norwegian industry magazine Byggeindustrien.
Ramboll is working on a similar project in Sweden, where the new Barkeby station is also located in a tunnel. Ramboll experts have recommended designing platform screen doors to protect passengers from wind and to improve ventilation.