The many challenges of the Hallandsås tunnel represent a turning point in Skanska’s environmental and sustainability work.
Hallandsås is one of the remaining obstacles to rapid, double-track rail traffic along the Swedish West Coast Line. The solution is two tunnels, each measuring 8.7 kilometers in length - the longest rail tunnels in Sweden.
One of the tunnels has already been excavated. By 2015, the first trains will be able to begin whistling along.
Trains will be able to cross at a speed of 200 kilometers per hour, compared with today’s 80 kilometers per hour and train capacity will increase from four to 24 trains per hour.
Transportation is improving but Hallandsås is a reminder that human activity also entails environmental risks.
The Hallandsås project began in 1992, when a state-owned contractor ran into difficulties after only about ten meters of boring.
Following a new procurement procedure, Skanska was commissioned to blast and seal the rock in 1996. After a joint decision with the customer, the National Swedish Rail Administration, attempts were made in 1997 to seal the ridge using a two-component material called Rhoca-Gil. The components were toxic in their individual forms but harmless in their hardened, polymerized state.
However, the water was contaminated by Rhoca-Gil and flowed out into a nearby brook. Fish died and cows were found ill. Work on the tunnel halted and the media headlines were dominated by the words “environmental scandal.”
Skanska immediately began a large-scale decontamination effort, performed in full safety equipment.
Following another procurement process, Skanska and Vinci were jointly commissioned to execute the design/build assignment in 2003, using a tunnel-boring machine, lining and freezing.
To enable the machine to break through, the weaker sections have been frozen. August 2010 marked the celebration of the breakthrough of the first tunnel.
Hallandsås became the starting point for the company’s focus on sustainability. One of the first steps was to phase out hazardous substances and introduce a chemical database designed to monitor and control the use of chemicals.
In 2000, Skanska became the first global construction and project development company to receive Group-wide ISO 14001 environmental certification
Learn more at: www.skanska.com/hallandsas
01. The Hallandsås tunnels need to be lined with concrete, in order to prevent water leakage. Approximately 180,000 cubic meters of concrete is required to line a 5.5 kilometer tunnel. The properties of the raw concrete must be fully analyzed and field-tested before it can be used.
02. Work on the Hallandsås tunnel has presented many challenges for Skanska over the years, and represents a turning point in the company’s environmental and sustainability work.
03. Learning and rising to the challenge. Hallandsås is what is known as a horst formed by faults in the rock. The rock quality varies between extremely hard primary rock and soft sections. To enable the tunnel boring machine to break through, the weaker sections of what is known as the Mölleback Zone have been frozen. A stretch measuring approximately 130 meters in length has been frozen and transformed into an ice cave with temperatures reaching minus 20 degrees Celsius. Freezing the rock also prevents water leakage.