JOB REPORT

Slab track crossing the Alps.

Paving a slab track in the Lötschberg Base Tunnel

The Lötschberg Base Tunnel is currently the third-longest tunnel in the world, surpassed only by the Seikan Tunnel in Japan and the Channel Tunnel crossing the English Channel. The 34.6 km long railway tunnel crosses the northern part of the alpine chain between Frutigen in the Bernese Oberland and Raron at the Lötschberg. Together with the Simplon Tunnel, the Lötschberg Base Tunnel provides the first high-speed transit route across the Alps in north-south direction, and is also part of the NRLA, the New Railway Link through the Alps.

A slab track in LVT design was paved on a single-track section of just under 7 km length on the stretch between Mitholz and Frutigen. LVT is short for “Low Vibration Track”; this method has been applied on many railway lines across Europe and Asia. The system does not use separate sleepers that connect the rails, but single-block sleepers instead that are mounted on flexible sleeper boots and are then held in position by cast concrete.

The SP 500 slipform paver from Wirtgen produced the concrete trough without reinforcement and placed the 3.5 m wide monolithic profile between the lateral embankments with pin-point accuracy. Around 500 m³ of concrete per day were paved in two-shift operation, equalling a daily progress of around 400 linear metres.

Heavy freight trains are now roaring through the Lötschberg Base Tunnel at speeds of up to 160 km/h, while passenger trains achieve speeds of up to 250 km/h. Additional advantages for the tunnel operators are improved riding comfort, a prolonged service life and minimized maintenance costs.