The presentation showed the significance of the Gotthard Tunnel to and within the European rail network, as well as its historic roots. It included information about the technical conditions of the overall project including geology and the programme.

The central section (contract C360 Sedrun) of the tunnel was visited in more detail describing the technical challenges of deep mountain tunnelling with up to 2000m of overburden, reached through an 800m- deep vertical shaft, covering geology, logistics, operations, safety and the contractual framework.

First Gotthard Tunnel
The history of the first Gotthard Tunnel underneath the Gotthard Pass, built more than 130 years ago, is one of industrialisation, political dispute, construction and social development.

In 1853 nine Swiss cantons formed the ‘Gotthard-Committee’, and first preliminary design work started. The Swiss engineer Wetli carried out a site survey from Erstfeld to Lugano in only five months. This is still recognised as a masterpiece in its field with regard to precision, even by today’s standards. The Gotthard idea was strongly boosted by the ‘Semmering-Railroad’ operating in eastern Austria and the ‘Mont Cenis Railroad’, being under construction.

In 1861 the idea of a 15km-long ‘great tunnel’ underneath the Gotthard Pass was presented for the first time.

In 1871 the states of Italy, Germany and Switzerland signed an international treaty to build and operate a Gotthard rail crossing. The issued tender document for the main tunnel was noticed in Europe and even in America. The main and critical conditions of that tender were:
• Only six weeks tender period,
• the contractor had to provide all details about methods, schedule and costs, and had to support that with substantial guarantees and bonds,
• the execution time was frighteningly short and very little was known about the geology of the Gotthard mountain.

Seven bids were submitted to the client and the contract was awarded to a Swiss company called ‘Enterprise du Grand Tunnel du Gotthard’ owned and managed by Louis Favre. He accepted ruinous contract conditions and guaranteed a maximum execution time of eight years.

Construction started on 13 September 1872. From the beginning the project faced immense technical difficulties, such as unstable and water-bearing rock formations. In 1875 the temperature in the tunnel rose to more than 33°C. An inadequate ventilation system complicated breathing in the tunnel filled with fumes. The original 3-shift pattern had to be reduced to five hours per shift only and the project was delayed.

At the end of July 1872 riots broke out in the labour force and an overstrained vigilante group shot down the rioters. Four workers died and many were injured. This incident received attention all over Europe and resulted in investigations about the social and hygienic conditions of the workforce. Two Swiss agencies investigated, but even though critical conditions were found, nothing changed.

In 1876/77 new calculations showed that the original budget of CHF 187M would overrun by approximately CHF 100M. This caused a crisis that was only solved because Italy, Germany and Switzerland increased their funding following another international conference.

On 19 July 1879 Louis Favre died of a heart attack during a site visit, only 223 days before the breakthrough.

On the 29 February 1880, a Sunday, tunnel breakthrough was accomplished and on 1 June 1882 the Gotthard railway opened. The cost was CHF 227M and it took approximately 18.4 million man-days to build it, with an average of 5472 workers on site.

The contractor and the client ended up in court with a dispute about the final payments, and the Enterprise du Grand Tunnel du Gotthard went bankrupt. Nevertheless the Gotthard Railroad Company decided to support Louis Favre’s daughter with a lifelong pension of CHF 10,000 per year to maintain her standard of living, but thousands of workers suffering from silicosis and crippling injuries were disregarded and forgotten.

Gotthard Base Tunnel
The Gotthard base tunnel is the centrepiece of the Swiss Alpine crossings. It is part of the European high-speed rail network and part of the Swiss railway upgrade scheme called ‘Bahn 2000’. The high-speed European network connects cities like London, Paris, Berlin and Rome and includes the Channel Tunnel Rail Link.

Currently there are four main rail Alp Transit routes:
(1) Loetschberg Tunnel in Switzerland –operational,
(2) Lyon – Turin route in France – under construction,
(3) Gotthard Base Tunnel in Switzerland – under construction,
(4) Brenner base tunnel in Austria – planned; but the Gotthard base tunnel is the most advanced high-speed alpine crossing.

Austria and Italy are working on the Brenner Base Tunnel project to relieve the current traffic congestion across the Brenner Pass, but this project has been delayed over the last decades mainly because of political and administrative disputes between Austria and Italy.

The first ideas for the Gotthard base tunnel were raised in 1947. A first preliminary project design was developed in 1962. Approval for the preliminary design of the current tunnel was granted by the Swiss authorities in 1995.

Currently a total of about 90 million tonnes of goods cross the Alps every year. More than half is transported by road. Switzerland is already transporting about 66 per cent of their share via railroad and this will significantly grow with the new Gotthard Base Tunnel.

The tunnel is designed to both transport freight and passengers, and current planning expects that around eight million people and 40 million tonnes of freight will go through the Gotthard Tunnel by 2020. This is an average of over 200 trains a day at speeds up to 160 km/h.

Passenger trains can travel through the tunnel at up to 200 km/h. The Gotthard Base Tunnel will therefore significantly reduce current travel times across the Alps, with the travel time between Zurich and Milan for example reduced by approximately an hour or 28 per cent.

The funding split for the overall upgrade concept of the Swiss Railways, ‘Bahn 2000’, including the Gotthard Base Tunnel comes 55 per cent from road taxes for heavy loads, 20 per cent from 0.1 per cent of Value Added Tax (VAT), 10 per cent from fuel taxation and 15 per cent from new loans. The people of Switzerland agreed to raise VAT to support the project by referendum in 1998.

The original overall programme for the Gotthard base tunnel showed a planned opening in September 2013. Current planning is to open the tunnel in 2017, but this might come forward by some months.

The Gotthard Base Tunnel is not a standalone project. The whole scheme actually consists of a chain of three major tunnels:
• The Zimmerberg Base Tunnel, 20km long on the northern approach tunnel.
• The Ceneri Base Tunnel, 15km long on the southern approach tunnel.
• The Gotthard Base Tunnel is the centrepiece, consisting of two 57km-long, single-track tunnels.

The main tunnels are connected by cross passages and have several access tunnels and shafts for emergency evacuation and ventilation. The overall scheme includes two ‘Multi Functional Stations’ with crossover tunnels and emergency stop facilities. The main tunnels have an outer diameter of approximately 9m and a separation of about 40m.

The client’s procurement strategy was to split the project into five sections let to three different joint-venture contractors:
• The northern sections Erstfeld and Amsteg have been let to AGN jv (Strabag and Murer, the Swiss subsidiary of Strabag),
• The middle section Sedrun has been let to Transco jv (Implenia (Switzerland), Bilfinger Berger (Germany), Frutiger (Switzerland) and Pizzarotti (Italy), with shares of 40, 28, 18 and 14 per cent respectively)
• The southern sections Faido and Bodio have been let to TAT jv (Implenia (Switzerland), CSC (Italy), Impregilio (Italy), Hochtief (Germany) and Alpine (Austria)

Implenia is part of two different joint ventures because it is newly formed in 2006 (post contract awards) through the merger of the two biggest construction companies in Switzerland, Zschokke-Locher and Bati-Group.

Sedrun contract C360
The Sedrun section can only be accessed through a kilometre-long, horizontal, access tunnel and an 800m-deep, vertical shaft. These features were constructed in advance in the years 1998-2001 under separate contracts.

The contract for the 6.5km-long tunnels and themultifunction station was awarded in April 2002 with an original execution time of 146 months –more than 12 years. It is noteworthy that the client awarded a 2kmtunnel extension to the original contract, taking it away from the other contract, in order to optimise the overall programme. This was due to the relative actual progress between the contracts.

The site installation accommodates living quarters with single rooms for 450 people (although the maximum workforce on site was 560), workshops and warehouses, a classification and separation plant for the excavated material, and all other necessary above-ground facilities for the project. The site is located approximately 1500m above sea level, so the installations had to be designed to withstand heavy snow and freezing temperatures in winter to guarantee operations all year.

The main features of the Sedrun contract are:

• Client: AlpTransit Gotthard AG
• Contractor: Transco JV formed of Implenia, Bilfinger Berger, Frutiger & Pizzarotti
• Design: Permanent design provided by the client with a design joint venture of Lombardi, Amberg and Poeyry

It is a unit price contract with remeasured bill of quantities governed by Swiss law. The contract value is CHF 1.5bn (USD 1.3bn) plus about CHF 200M (USD 1.7bn) escalation to date. The contract contains a dispute resolution clause with a permanent Dispute Resolution Board (DRB) consisting of three members. An option to involve normal legal jurisdiction is given, but to make use of it would be very unusual. Usually solutions are found and agreements are reached at project level. The DRB normally only supports queries about the principle application of law or regulations.

The contract provides for fair risk sharing, such as:
• Geotechnical Baseline Report (GBR) given, with any deviation from it being at the client’s risk,
• Design provided by the client with design risk remaining with the client,
• Contract dates cannot move forward, only backwards,
• Overheads and preliminaries are paid for in accordance with the actual geology.

A joint risk register is maintained at all times. It is updated by regular riskassessment meetings with the client, the designer and relevant third parties. The main topics of this risk register are:
• Occupational Safety, Health & Environment (OHSE),
• Geological risk,
• Quality risk,
• Programme risk,
• Budget risk,
• Design risk.

The project complies with the highest international safety standards. Its site safety plan has 132 pages, is continuously updated and covers all relevant aspects of such a project. Typical OHS requirements are:
• Maximum air temperature 28°C,
• Maximum Relative Humidity 70 per cent,
• Maximum levels for all gas concentrations,
• Regular health checks for all personnel.

However this project also has some safety aspects that are not quite so common, such as:
Avalanches: The risk of being hit by an avalanche is continually assessed and monitored by trained specialists, if necessary several times a day, according to the actual weather situation. The findings and assessments are based on the avalanche risk map, which is part of the overall safety plan.
Fire rescue: The local fire brigade of Sedrun is too small to cope with the requirements of such a project, therefore fire rescue crews were established within the labour force of the project on a voluntary basis. They consist of:
• eight teams of four members plus one team leader, and
• one captain plus four deputies, to cover all shifts.

They have to prove and maintain their physical fitness, and have a maximum age of 40. They receive special training and professional equipment to be able to fulfil their duties safely.

The only objective of these rescue teams is to save human lives by evacuating people. Extinguishing fire is not a primary goal. In the case of a major fire the tunnel will be abandoned if all people have been evacuated.

The project has agreed a target with the client to achieve an accident rate of less than 200 reportable accidents per 1000 men-years. This might sound a lot but it must be noted that this is based on Swiss reporting rules and is actually significantly lower than the average in Swiss tunnelling. The target has been achieved and even undercut by the project to date. This has a significant positive effect on the premiums for the accident liability insurance.

The special technical challenges of this project are:
• Logistics through an 800m vertical shaft (formed by deep mining techniques),
• 2500m overburden with extreme rock temperatures and rock pressure,
• Existing civil structures (e.g. existing concrete dam),
• Tunnelling in loose rock with 800m overburden,
• Dewatering and ventilation.

Major parts of the site installation such as workshops, a concrete batching plant with a capacity of 900m3 per day, a dewatering system including desanding and the pumps, transformers, etc, are located below ground in the caverns at the bottom of the access shaft. All excavated materials, building materials and equipment have to be transported by the vertical hoist.

The main hoist is a 4-rope Koepe system as is used in deep mining, with an installed power of 4.2MW. The 2-stage staggered lifting cage has a payload of 50.8 tonnes. The daily capacity of the system is 6500t/day plus 50 railcars and 960 personnel. A maximum of 40 persons can be carried in one lift. The lifting speed is 18m/s for materials and 12m/s for people.

The installed dewatering system consists of eight pumps with a total capacity of 1000 litre/s over a vertical height of 800m. This was the contractual worst case. The actual volume of water intake for all the tunnel drives was in the range of only 20 litre/s.

To service and support the tunnel drives to the south a suspended backup system was installed. This suspended unit held all necessary facilities for cooling, ventilation, dust extraction, rescue units, supply units, conveyors, etc. To move the suspended unit forward took around 4 -5 days for every 180m of tunnel drive.

The drives toward the south turned out to be normal drill-and-blast operations with advance rates of up to 9m/day. The peak performance was during the excavation of the multi-function station with eight headings at one time and 5500 linear metres of excavation in 2004.

In the north (left hand side of the geological section) the geology is governed by granite. The majority of the ground conditions towards the south are gneiss. In between the rock consists of unaltered sediments, such as dolomite and limestone, with schists untouched by the orogenesis in sandwich-type layers. Towards the north a vast shear zone was predicted composed of kakirite, which was crossed at right angles (the shortest way). Still nearly 1200m had to be excavated in this geology.

Only one site investigation from the surface was executed, as a single core, especially to investigate the area of the kakirite zone. The correlation between the drilled core and the actual findings on tunnel level was quite remarkable.

One of the biggest challenges at Sedrun was the drive through this kakirite fault zone. Radial deformations of up to 700 mm were predicted, resulting in a 2-stage support system:
• First a full-face, circular section of up to 140m2 was excavated at a length of 0.6-1.0m per round, with planned overbreak of up to 700 mm to allow for the predicted deformation,
• The face was stablised with horizontal rock bolts, 12–18m long (resulting in up to 210 m of rockbolts per metre of tunnel),
• Steel arches were placed at a minimum spacing of only 300 mm, which allowed radial deformation (up to 9.4t of steel per metre of tunnel used),

In addition radial rockbolts completed the support at this stage (290m of rockbolts per metre of tunnel).

At the second stage, well behind the face and after the radial movement was finished, steel-fibre-reinforced shotcrete up to 450mm thick was placed.The tunnels later received an inner lining of unreinforced in situ concrete.

The standard thickness of the concrete lining is 300mm, but up to one metre in the area of the shear zone.

Non-standard cross sections, such as the multi-function station have been steel reinforced. The tunnels are fully drained with a waterproof membrane. The design allows a water inflow of only10g/km.

The current status is that still approximately 650m of rock has to be excavated in Sedrun with another 2200m by TBM from Faido before the final breakthrough is reached later this year.

Another 350,000m3 of concrete have to be poured before the handover of the tunnels in mid-2012 and the finishing works, such as the shaft lining and the works at the top of the shaft, will continue till 2014.

The final breakthrough for this tunnel is planned for the fourth quarter of 2010; it will then make the longest transport tunnel in the world. Even with the prospects and resources of the 21st century a project like the Gotthard Base Tunnel is at the cutting edge of technology.

Discussion
As is usual the Chairman invited questions on the presentation and Mike McConnell (retired, ex-Balfour Beatty) was very interested in the contract conditions used, which attempted to anticipate every eventuality on the project and develop an all- embracing bill of quantities. He wondered if this was worth the effort.

Did it cover all the conditions encountered? The speakers agreed that the design was done in great detail and considered many eventualities. In broad terms it achieved what it set out to do but inevitability with a project of this nature there will be many changes and the contract cost had risen from EUR1.2bn (USD 1.4bn) to EUR1.6bn (USD 1.9bn).

Richard Brown wanted to know whether the tunnel was straight or curved and if curved, the minimum radius used both horizontally and vertically. The speakers were not sure of the actual figures but it was a high-speed line and was in the 15,000-16,000m range.

The concept of a passenger station at Sedrun was also queried. Had this now been cancelled or did it remain part of the scheme. Michael Gutzeit noted that this was an idea that came late in the project development, but stops on a high-speed line had a significant impact on capacity. So it was not to be included at this stage but could always be developed at a later time if the next generation decided it was necessary.

Peter Townsend (KBR) wondered how accurate the Ground Reference Conditions (GRC) proved to be. Hans Bartschat noted that, in the northern section where the ground was only investigated from the surface, the correlation was surprisingly good. To the south the geology was generally better than the GRC implied.


Gotthard Base Tunnel project time and chainage chart Section along the route of the Gotthard Tunnel and related Zimmerberg and Ceneri base tunnels Schematic of the Gotthard Base Tunnel runing bores and access routes Schematic of the Sedrun section of the Gotthard Base Tunnel with access routes Surface accommodation and other facilities near Sedrun Sedrun shaft bottomwith hoist cages Longitudinal geological section through Sedrun Advancing the east bore south under steel arches and shotcrete