Innovation in boring

Comprised of four tracks to Oslo Central Station, Norway’s largest public transport hub, the Follo Line Project will significantly improve the daily life of commuters once completed in 2021

Stretching from Norway’s capital, Oslo, to the city of Ski, the Follo Line Project is currently Norway’s largest transport project and will comprise of approximately 64 kilometres of new railway tracks. Forming the core part of the InterCity development southwards from Oslo, the project is split into four subprojects and involves the delivery of 22 kilometres of new double track line and follo-line-138-bwill comprise of a 20 kilometre long tunnel – the longest railway tunnel to date in the Nordic countries, as well as the first railway tunnel of this length in Norway to have separate tubes.

This milestone in the history of the country’s rail projects has led to the use of tunnel boring machines (TBM) as well as drill and blast and drill and split for the excavation process. Additionally, tracks will be realigned for the existing Ostfold Line on the approach to Oslo Central station and between the tunnel and new Ski Station. In line with these developments, extensive works at Oslo Central Station and the construction of a new station at Ski will also take place.

In tandem with an existing line with traffic to local stations, the direct trains trafficking the new Follo Line (upon its completion) will significantly improve the daily life of commuters. The line will be constructed with connections to several platforms. The existing Ostfold Line has reaching its capacity limit due to increased population growth. By linking residential and working areas together effectively, the Follo Line will positively contribute to the development and growth of the region located south east of the capital.

Managing this major project is Jernbaneverket (the Norwegian National Rail Administration), which will use its experience in owning, maintaining, operating and developing the Norwegian railway network to ensure the project is not only completed in 2021 but will also provide passengers with a number of benefits. These include a 50 per cent reduction in journey time from Oslo to Ski thanks to efforts including a possible speed of up to 250 kilometres per hour.

“Jernbaneverket was established in 1996 when it was made a separate company, having earlier been part of state-owned passenger company Norges Statsbaner (NSB). The budget has increased significantly over the last five to six years and the investment portfolio is now NOK 10 billion; this maintenance budget has also increased. The investment in railway structure is expected to stay high in the years to come, particularly as part of the InterCity development in the southern part of the country. Improvements and the construction of new double track high speed rail follo-line-138-cinfrastructure, between a triangle of cities, is expected to have a budget frame of NOK 160 billion until 2025,” states Mikael Bors, Market Director of the Rail Administration.

Using the expertise of its employees in a range of specialist fields such as electrical engineering, construction, telecommunications, social planning, scheduling and traffic management, Jernbaneverket is in the process of ensuring the core part of the InterCity development project, the Follo Line project, progresses in a timely manner. Erik discusses the project and the developments so far: “The new double track railway line forms an important part of the InterCity rail development southwards from the capital and includes the longest railway tunnel to date in the Nordic countries. With its novel methods and solutions, this project offers a model for future railway project developments in the region. This new railway line is under construction with a 20 kilometre long hard rock tunnel; it is a major project with high demands regarding quality, cost and schedule. In addition, restrictions concerning locations close to sensitive urban infrastructure require execution with the highest level of precision and expertise.

“Around 30 per cent of the work in this large scale project has now been performed and the project is overall on schedule. Two out of four tunnel boring machines have started the excavation of the main part of the tunnel, and the TBMs that have been baptised and started will excavate in the northward direction towards Oslo Central Station. Another two will start operating in November and December of 2016 and will work in the southerly direction towards the city of Ski to be connected to a cut-and-cover section. The two TBMs heading north will cross close above a new sewage tunnel and the two TBMs heading south will cross close above a new tunnel for a relocated stream. To avoid potential challenges with the construction of the railway tunnels, both the sewage tunnel and the river tunnels are constructed with highly reinforced concrete lining as part of their structure. All four TBMs are double shield machines, designed for extreme hard rock conditions; the diameter of each machine is 9.860 metres,” says Erik Smith, Project Director of the Follo Line Project.

A pilot project for new contract models as well as new tunnel excavation methods, the Follo Line Project is using EPC contracts, conventional drill and blast combined with drill and split methodology and tunnel boring machines to pave the way for further innovation, shared knowledge and modernisation. It will also aid in the building of alliances between Norwegian and foreign engineering construction companies. “Norway is currently modernising its infrastructure, which means many upcoming projects in the coming years; the introduction of TBM tunnelling will help the development of the Norwegian tunnelling industry and innovation for the Norwegian market,” confirms Erik Smith.

As the project moves forward, Jernbaneverket and the EPC contractors involved will continue to operate in a safe and efficient manner during the production of the 20 kilometre tunnels while also solving challenges such as the construction of new infrastructure in densely populated and historical urban areas close to Oslo Central Station. With the latter issue, close co-operation with road authorities and other parties, as well as respect to restrictions surrounding the medieval park will ensure the project is completed safely, on time and to budget.

“Over the next months we will cultivate our role as developer; it is important to follow up contracts regarding performance, milestones, working conditions and more to obtain and secure the performance that will enable the contractors to deliver the new infrastructure with the right quality, in due time within budget,” concludes Erik Smith.