The Woodsmith Project in North Yorkshire has achieved another landmark in global tunnelling, as its tunnel boring machine (TBM) Stella Rose passed the 30-kilometre mark on 3 December. The achievement extends what is already recognised as the world’s longest single continuous tunnel excavated by one TBM, surpassing the previous world record of 25.8 km—and advancing further with each passing day.
Located near Whitby, the Woodsmith Project is being developed to access the largest known deposit of polyhalite anywhere in the world. Polyhalite is a naturally occurring, low-carbon mineral fertiliser that contains potassium, sulphur, magnesium and calcium, and is expected to play an important role in supporting more sustainable global farming practices for decades to come.
World-class tunnelling feat
On behalf of project owner Anglo American, construction specialist STRABAG is delivering the project’s most technically ambitious element: the world’s longest conveyor tunnel. Once complete, the tunnel will form the backbone of the permanent Mineral Transport System (MTS), carrying polyhalite ore from deep beneath the North York Moors National Park to a processing facility on Teesside, approximately 37 km away.
The tunnel is being excavated at depths of up to 1.6 km below ground, passing through multiple geological formations. Stella Rose operates continuously, with crews working around the clock to maintain progress while meeting stringent safety and environmental standards appropriate to a nationally protected landscape.
The milestone breakthrough at 30 km was overseen by Ronnie Birkett, STRABAG UK’s Senior Occupational Health Advisor, highlighting the project’s strong emphasis on workforce wellbeing alongside engineering performance.
Innovation and regional impact
Commenting on the achievement, Andrew Johnson, Woodsmith Project Director, described the milestone as a testament to the project’s scale and ambition:
“We are incredibly proud of this milestone. The Woodsmith Project is one of the most innovative mining developments in the world today and construction is progressing well.”
Beyond its technical significance, the project continues to deliver substantial economic benefits to the region. Around 1,100 people are currently employed, with approximately 75% recruited locally, supporting jobs across construction, engineering, logistics and professional services.
Johnson added:
“We are also proud to have a small international workforce with the specialist expertise we need for this unique world-class engineering project that will provide employment for hundreds of local people for many, many years to come.”
Looking ahead
When operational, the Woodsmith Project is expected to supply polyhalite to agricultural markets worldwide, helping farmers improve soil health and crop yields while reducing environmental impact. With tunnelling continuing to push further beyond 30 km, the project is not only reshaping the future of fertiliser production but also rewriting the global record books for underground construction.
As Stella Rose continues its advance beneath North Yorkshire, the Woodsmith Project stands as a defining example of how large-scale infrastructure, innovation and sustainability can be combined in modern mining development. For further information please visit the tunnelbuilder archive. 50/25.
