WHEN it opens for full commercial operation for scheduled train services on December 11 2016, the 57km twin-bore Gotthard base tunnel will be the longest railway tunnel in the world. The official opening of the tunnel will take place six months earlier, on June 2 2016, following a formal handover to Swiss Federal Railways (SBB) from its 100% subsidiary, Alptransit Gotthard (ATG), the body in charge of constructing and commissioning the tunnel.

A six-month pilot testing programme was recently carried out on the tunnel's first completed section at the southern end of the west bore between the south portal at Bodio and the multi-function station at Faido. Concluding in June, a total of 650 runs took place during 78 test days at speeds of up to 220km/h using SBB rolling stock and personnel.

The results from the tests are now being evaluated by SBB and ATG, and although every conceivable aspect is under examination, there is a particular emphasis on the interfaces between the tunnel's various systems - track, power supply, tunnel control, communications, and security and safety systems.

GBT-MFSWhile the finishing line is now in sight, it has been a long haul to reach this stage. Construction of the Gotthard base tunnel started as long ago as 1996, with work commencing at both ends - Erstfeld and Bodio - and three intermediate sites including the approximate halfway point near Sedrun, where vertical twin 800m shafts were constructed to provide access. The hugely ambitious project is a major part of Switzerland's modal shift policy to transfer as much transit freight as possible from road to rail in the face of the rapid increases in volumes predicted on the Rotterdam - Genoa corridor.

The Gotthard will also be used by high-speed passenger trains, cutting journey times between Zürich and Milan by around an hour to less than three hours. SBB has ordered 29 transalpine EMUs from Stadler to operate these services. Part of the New Railway Link through the Alps (NRLA) which will provide faster north-south links through the mountains, the tunnel will cost around SFr 9.8bn ($US 10.83bn) according to current estimates, and is financed mainly by taxes on HGV traffic and mineral oil.

Around 80% of the tunnelling was carried out by 9m-diameter tunnel boring machines, although some sections were excavated by conventional drill and blasting because of difficult rock conditions. As the world's deepest tunnel, with a rock overburden of up to 2300m, a special reinforcement technique which uses multiple steel rods to combat deformation was used in places.

The final breakthrough in the east tunnel was made in October 2010 with a deviation of only 8cm vertically and 1cm horizontally. However, there was still a long way to go. Once the construction gangs moved out, the installation teams moved in, in this case the Transtec Gotthard consortium which secured a SFr 1.7bn contract to fit out the tunnel in May 2007.

The consortium comprises Alpiq, the lead contractor, along with Alcatel-Lucent/Thales Railway Signalling Solutions, Balfour Beatty Rail and Renaissance Construction. By the end of August, its teams of engineers had completed 84% of the infrastructure work. Indeed most of the track is now in place following a vastly complicated eight-year exercise that included planning, logistics, temporary installations, track laying (mostly slab track), and cable-laying for the 50Hz power supply for general use, and installation of a 15kV 16.7Hz system for traction supply, communications and signalling, safety and security systems.

According to Alpiq's CEO Mr Marco Hirzel, the detailed plan of action comprises more than 18,000 procedures, a figure that is still rising. But with access for transport, workers and material only possible from each end of the tunnel, and with 250 people working at up to six sites simultaneously, constructing the tunnel presented a number of logistical challenges, not least maintaining the power supply and communication lines through more than 114km of tunnel.

Hirzel's colleague Mr Roland Herlig, CEO of Alpiq Burkhalter Technik (ABAG), is also well aware of the difficulties. ABAG is responsible for electrical installations, including ventilation and lighting which Herlig says is the first priority for any tunnel project. "It is essential to get this right early on given that temperatures in the tunnel can rise to 40oC with humidity of 90%, making working conditions at best uncomfortable and potentially dangerous," he says.

ABAG drew on its experience of working on the electrical installations in the Lötschberg Base Tunnel, and it possesses two specially designed wagons for cable laying, which can carry up to 30 tonnes of material at a maximum speed of 40km/h.

ABAG is also responsible for equipping the cross-passages, emergency exits situated every 320m which allow passengers to escape to the parallel tunnel in an emergency. There are 178 cross-passages, which are fitted with heavy heat-proof doors at either end, while ABAG is also installing emergency lighting, supported by an emergency power system. In the event of an emergency evacuation, special stations have been built at Faido and Sedrun which have emergency facilities and track crossovers in both directions.

The cross-passages are also the location for wayside control cabinets, with yellow cabinets hosting power supply equipment, blue cabinets telecommunications and grey cabinets safety and security systems, including wayside ETCS Level 2 equipment, the only signalling, control and train protection system installed in the tunnel.

The power supply for train operation and catenary installation is being masterminded by ARGE 16.7Hz, a partnership between Balfour Beatty Rail and Kummler + Matter. ARGE, too, has three specially designed, powered vehicles for the installation, and project leader Mr Martin Kuhn says the major challenge has been fitting all of the equipment above the train while leaving an adequate safety margin.

The result was a very compact dual catenary system suitable for high-speed and high power operation which was designed and successfully tested at speeds of over 200km/h.


Asked why SBB is not deploying the same overhead catenary system in the Gotthard tunnel as it used in the Weinberg tunnel and at Löwenstrasse station on the new cross-city link in Zürich, Kuhn says that this technology was not far enough advanced at the time when the specifications for the Gotthard were outlined. In this system, the overhead conductor rail consists of an aluminium profile with the copper catenary wire clamped inside, which delivers the same amount of power as a standard installation but saves on the installation space required, reducing the diameter of the tunnel and massively reducing costs. For the Gotthard project, however, the aim was to use only tried and tested technology, and there had to be a cut-off point.

SBB is currently preparing to obtain an operating licence from the Swiss Federal Office of Transport for the line and it anticipates starting test operations on May 27 2016. In addition to acquiring new rolling stock, SBB is preparing an operating, intervention and maintenance system and training around 2900 employees to use both the Gotthard and the 15km Ceneri tunnel to the south, which is under construction and is due to open in 2019. "The logistics of equipping the tunnel are extremely complex, but maintenance is just as complicated," says Mr Peter Jedelhauser, project leader in charge of the north-south Gotthard axis at SBB.

Added to these considerations is the need to upgrade access lines to the north and south to create a 4m corridor and adapt stations for 750m-long trains, as well as making sure all trains are equipped with ETCS Level 2.

As for controlling the operation of high-speed passenger, regional and freight trains in each direction, SBB has developed a new system which is designed to maximise traffic flow and minimise delays. It uses three passing loops for three trains at each end of the tunnel. Therefore six freight trains an hour travelling at 100km/h will pass through the tunnel with a short wait at either end, allowing passenger trains to operate at 200km/h through the tunnel without stopping, thus maximising the use of the Gotthard tunnel and giving rail a real leg up over competing modes.