Continue reading
Ten years after the opening of the Gotthard Base Tunnel, the BORFLEX elastomeric liners are still in service without requiring any maintenance.
1 June 2026 marks the tenth anniversary of the opening of the world’s longest railway tunnel. For the BORFLEX Group, the event provides an opportunity to reflect on a decade of continuous operation of its elastomer liners in the heart of the Alps and to position its technology for major construction projects in the future.
A decade of proven service in the heart of the Alps
Inaugurated on 1 June 2016 by the heads of state of Switzerland, Germany, France and Italy, and opened for commercial service on 11 December 2016, the Gotthard Base Tunnel (57 km) is the flagship project of Switzerland’s New Rail Link through the Alps (NRLA) programme. Ten years on, the infrastructure handles heavy traffic of up to 260 freight trains and 65 passenger trains a day, under some of the most demanding conditions of vibration and mechanical stress in the world. At the heart of this infrastructure are 212,000 elastomeric sleeves developed and manufactured by the BORFLEX Group, which encase the two-piece sleepers and ensure they are isolated from the concrete slab. Installed along 57 km of ballastless track, these components simultaneously reduce the vibrations transmitted to the bedrock, attenuate structure-borne noise, provide electrical insulation for the sleeper and allow for the replacement of individual components without the need for major work on the infrastructure.
“Ten years of continuous operation without replacement is the most demanding industrial validation test there is for a railway elastomer component. Complete control of the entire production chain — compound formulation, finite element simulation, mechanical qualification on an MTS Landmark test rig, and mass production — is our decisive competitive advantage. ” — Thierry GERME, KAM Railway, BORFLEX Group
BORFLEX slippers at the Gotthard Pass: key points
- Quantity supplied: 212,000 slippers
- Length of track fitted with equipment: 57 km
- Delivery period: 2013–2014–2016
- Maximum operating depth: 2,300 m below the mountain range
- Traffic handled since 2016: up to 325 trains per day (freight and passenger)
A rapidly growing ballastless market
The Swiss case study comes at a pivotal moment for the global ballastless track market. According to Verified Market Reports, the segment was valued at US$3.2 billion in 2024 and is expected to reach US$5.5 billion by 2033, representing a compound annual growth rate of 7.1 per cent.
Other consultancies (such as Dataintelo) put forward higher market valuations of up to US$10.5 billion; however, they all agree on the underlying structural trends: urbanisation, modal shift and growing noise control requirements in densely populated areas.
Tunnel applications are the fastest-growing segment. Major projects currently under way, such as Lyon–Turin (Mont-Cenis, 115 km), Brenner (64 km, due to open in 2032), and metro extensions in Asia and the Middle East, rely predominantly on double-block sleeper solutions with elastomeric pads, for which BORFLEX is one of the leading European suppliers.
Integrated engineering, from formulation to simulation
Developed and refined since 1978, BORFLEX technology is based on an integrated system comprising an elastomeric insole, a microcellular rubber sole with calibrated static and dynamic properties, and, depending on the configuration, a connecting bar between the two blocks of the crosspiece.
Key technical specifications:
- Reduction in the transmission of vibrations to the ground and surrounding buildings
- Attenuation of structure-borne noise generated by rail traffic
- Static and dynamic stiffness optimised using finite element analysis (FEM)
- Compatibility with LVT double-block sleepers, with and without connecting bars, as well as with metro and tram tracks
- In-house developed elastomer compounds, including variants incorporating recycled rubber (VALUE RUBBER programme)
- Manufacture by vulcanisation (compression, transfer, injection) or thermoplastic injection moulding
- Integrated electrical insulation, protecting infrastructure against the spread of stray currents
- IRIS and ISO 9001 certifications; compliance with REACH, RoHS and Euroclass standard NF EN 13501-1
Clients across five continents
Beyond the Gotthard Pass, BORFLEX sleeper pads are used in some of the world’s most demanding railway projects:
| Project | Background |
|---|---|
| Gotthard Base Tunnel (Switzerland) | 57 km; the world’s longest railway tunnel, which opened on 11 December 2016 |
| The Lötschberg and Zimmerberg Tunnels (Switzerland) | New Trans-Alpine Railway Line (NLFA) |
| The Bötzberg, Grauholz and Mattstetten–Rothrist tunnels (Switzerland) | Modernisation of the SBB rail network |
| Zurich, Kloten and Lausanne railway stations (Switzerland) | Deployment in a densely populated urban area |
| Channel Tunnel (France / United Kingdom) | A long-standing institution in operation since 1994 |
| Metro systems in Hong Kong, Taiwan and Rio de Janeiro | Maximum vibration limits in dense urban areas |
| Brazil (Porto Alegre) and the United States | High-speed and urban rail networks |
| Cairo (Egypt) and Lima (Peru) | Establishing a presence in Africa and South America |
| Metro lines in Greece, France and Italy | Further European deployments |
Technological innovation and integrated R&D
The BORFLEX Group continuously invests in its research and development capabilities. The group has an in-house materials characterisation laboratory, an MTS Landmark hydraulic test rig for mechanical qualification, and utilises advanced finite element method (FEM) simulations for the design of elastomer components. This data-driven approach ensures the precise optimisation of the static and dynamic stiffness of each component, in line with the regulatory requirements of each project.
Media resources available
Video presentation of the roll-out at the Gotthard Base Tunnel
