Project Profile: Arna-Bergen Double Track

The Arna-Bergen Double Track project represents a pivotal upgrade to Norway’s Bergen Line, resolving a critical capacity bottleneck through advanced engineering and new infrastructure. Executed by Bane NOR, this project involved the construction of 8.1 km of new double track, anchored by the 7.8 km Ulriken Tunnel—the first Norwegian railway tunnel excavated with a Tunnel Boring Machine (TBM). The integration of modern signalling, power systems, and station upgrades has significantly enhanced operational efficiency, safety, and service frequency between Arna and Bergen.

Technical Specifications

The core of the project was the construction of the new 7.8 km Ulriken Tunnel, running parallel to the existing structure. This undertaking was a technological milestone for Norway, marking the first deployment of a hard-rock Tunnel Boring Machine for a railway project. A 1,800-ton Herrenknecht TBM was utilized for the main excavation, complemented by traditional drill-and-blast methods for the initial transit loop near Arna Station. For enhanced safety and maintenance, multiple diagonal cross-passages were constructed to connect the new and old tunnels, ensuring robust emergency evacuation routes and operational flexibility.

Comprehensive modernization of the line’s control and power systems was critical to achieving performance goals. A new Class B interlocking system was installed at Bergen Station with the capability to manage traffic for both Bergen and Arna, centralizing control and improving safety. The Arna-Fløen segment received an entirely new 11 km overhead contact line, supported by an upgraded earthing installation and power supply from the Arna converter station. Substructure enhancements included improved drainage, new cable conduits, and ballast replacement, ensuring the long-term stability and reliability of the track infrastructure.

The passenger interface at Arna Station was completely redeveloped to improve accessibility and user experience. The project included the construction of new ramps, stairs, and a widened underpass, alongside a new technical building to house the line’s essential control systems. This holistic approach ensures that the benefits of the infrastructure upgrade translate directly to a more comfortable and efficient journey for passengers.

Key Takeaways

• Capacity Enhancement: The double-tracking project fundamentally resolves a major bottleneck on the Bergen Line, enabling a significant increase in the frequency and reliability of both passenger and freight services.
• Technological Milestone: The successful deployment of a Tunnel Boring Machine (TBM) for the Ulriken Tunnel set a new precedent and benchmark for large-scale railway infrastructure projects in Norway’s challenging geology.
• Integrated System Modernisation: Upgrades were not limited to track and tunnels; the comprehensive renewal of signalling, power systems, and station infrastructure delivers a holistic improvement in operational safety, efficiency, and passenger experience.

Frequently Asked Questions (FAQ)

What is the primary benefit of the Arna-Bergen double-tracking project?

The primary benefit of the Arna-Bergen double-tracking project is a significant increase in railway capacity between Arna and Bergen. This allows for more frequent train services, reduces travel times, and improves the reliability for both passenger and freight transport on the critical Bergen Line.

What technology was used to build the new Ulriken Tunnel?

The new 7.8-kilometer Ulriken Tunnel was primarily constructed using a Tunnel Boring Machine, or TBM. This was the first time a TBM was used for a railway tunnel in Norway, marking a major technological advancement in the country’s infrastructure construction methods.