In focus: Gotthard & Ceneri Base Tunnels
The Gotthard Base Tunnel – the longest train tunnel in the world – has entered into service, while work on the Ceneri Base Tunnel continues to make great progress.
The two projects are integral components of a multi-million pound scheme designed to construct the New Rail Link through the Alps (NRLA) in Switzerland. Once complete, the New Rail Link will make it possible to cross the Alps from the North to the South in just 2 hours and 40 minutes.
The new flat route will allow efficient rail transport for both goods and passengers.
The first element of the project – the Gotthard Base Tunnel – consists of two 57-kilometres-long single-track tubes. The tubes are connected by cross passages at 325 metre intervals.
Including all cross-passages, access tunnels and shafts, the total length of the tunnel system is over 152 km, joining the north portal at Erstfeld to the south portal at Bodio. The system includes two multifunction stations at Faido and Sedrun, which act as emergency stop stations.
The work contract for the Gotthard Base Tunnel railway systems had a total value of 1.7 billion Swiss francs, making it one of the largest contracts for railway systems in the world and certainly the largest work contract for AlpTransit Gotthard Ltd. A Railway Systems General Contractor was tasked with the installation of the tunnel’s railway systems, while the Transtec Gotthard Consortium was responsible for the installation, planning and the commissioning of the rail systems.
Before regular operations of the Gotthard Base Tunnel commenced on 11th December 2016, operator Swiss Federal Railways SBB gave passengers the opportunity to take a look at the interior of the magnificent structure. The once-in-a-lifetime tour showcased the dimensions of the gigantic tunnel system and provided passengers with the opportunity to see an area of the tunnel that will not be visited again.
Running from August to November 2016, a special ‘Gottardino’ train carried visitors to a record depth in the rock of the Swiss Alps, where passengers were able to stop off at the Sedrun stop. Now that trains are travelling through the Gotthard Base Tunnel at high speed, a stop at Sedrun will no longer be possible.
The Gotthard Base Tunnel is one of two tunnels at the heart of the AlpTransit scheme – the other is the Ceneri Base Tunnel, which is currently under construction in Switzerland’s Canton Ticino. The Ceneri Base Tunnel comprises two single-track tunnels, each measuring 15.4km in length.
Commenting on the project, Maurus Huwyler of AlpTransit Gotthard AG, said:
“After commissioning of the Gotthard Base Tunnel, the 15.4-kilometers-long Ceneri Base Tunnel is Switzerland’s largest tunnel-construction project. Although the Gotthard Base Tunnel forms the heart of the New Railway Link through the Alps (NRLA), it is only together with the Ceneri Base Tunnel that it creates a continuous flat route.”
“To link the Ceneri Base Tunnel to the existing railway line, various structures are being built at the Camorino junction. Most prominent is a four-track bridge over the A2 motorway and the two railway viaducts.”
Work began on Ceneri Base Tunnel in 2006. At present, structural work has been completed and the installation of railway systems will take place throughout 2017.
In addition to the planned route, a link between Locarno and Lugano is being added, to improve passenger journeys.
“At the request of the Canton of Ticino, and to meet its needs, a Locarno-Lugano link is also being implemented. It reduces the journey time for regional traffic between Locarno and Lugano from today’s 55 minutes to 22 minutes. For international traffic it will be a reduction of around 10 minutes.”
The Ceneri Base Tunnel is expected to open in December 2020.
HBI Haerter Consulting Engineers specialise in the design and plan of tunnel ventilation systems, aerodynamics and thermodynamics of tunnels, risk analysis and safety. Working on the Gotthard and Ceneri projects, HBI elaborated ventilation concepts and assisted in their implementation.
HBI also analysed the tunnel environmental conditions (tunnel climate), studied the aerodynamics (traction power demand of trains, pressure loads, aural comfort, sonic boom, etc.) and worked on resulting concepts and specifications for the civil structures and the electro-mechanical equipment in the tunnel.
Commenting on HBI’s involvement, Dr. Peter Reinke of HBI Haerter Consulting Engineers, said:
“For HBI, the involvement in these projects gave us the opportunity to apply and extend our experience and engineering competence in designing more reliable, safe and economical high-speed rail tunnels.”
High safety and comfort inside the Ceneri Base Tunnel with the COMLAB tunnel radio system
The Swiss company COMLAB AG equips the two 15.4 km long single-track tunnels with an extremely complex tunnel radio system, consisting of the digital redundant rail radio (GSM-R), the safety radio (POLYCOM) and the public mobile telecommunications systems (GSM and UMTS). As a result, train drivers and emergency services as well as train passengers will be supplied with mobile communications.
The highest priority for this system solution is reliability. Due to the thick layers of rock, no radio signals can be received inside a mountain. Despite this, rescue teams, the fire brigade and the police are reliant on being able to communicate with one another in the tunnel in the event of an emergency on the one hand, and on the other hand data transmission to the driver’s cab must be guaranteed in real time. At high speeds (up to 250 km/h) train drivers can no longer see the signals in the tunnel, meaning that they have to be able to rely entirely on the train control system.
In order to be able to guarantee continuous coverage, the signals from the appropriate base stations are received in the railway infrastructure buildings at the tunnel portals, processed and routed inside via glass fibre cables, where they are boosted every 975 m by special tunnel radio repeaters and emitted via two leaky feeder cables in both tunnels. The system ensures high reliability through its design with multiple redundancies, whereby other system components automatically take over the operation in the event of a partial failure. Communication can therefore be ensured even in the event of a fire in the tunnel.
With this system, last but not least, great importance is placed on the comfort of the rail travellers who can, as a result, make phone calls and surf the Internet at any time in the tunnel.
Along with the complex technology, the numerous interfaces with the emergency services, authorities, SBB [Swiss Federal Railways] and a variety of different telecommunications providers make the project a challenge.
Currently the acceptance by the Swiss federal office of transport is taking place.