To support the safe construction of Sweden’s West Link project (Västlänken), Hottinger Brüel & Kjær (HBK) has provided an advanced structural monitoring solution that will be used during the transformative rail infrastructure project to create an 8-kilometer underground rail connection, beneath central Gothenburg, which will include more than 6 kilometers of tunnels and three new underground stations.

Working with the Swedish Transport Administration — Trafikverket — and engineering consultancy COWI, HBK’s technology will provide real-time structural insight at Korsvägen Station — one of the project's most technically demanding construction sites.

Fiber Bragg Grating strain and temperature sensors enabled continuous monitoring of structural behavior during excavation. Source: HBK

Deep construction below a densely populated urban environment presents significant engineering challenges. At Korsvägen, excavation required careful management of load transfer between highly stressed bedrock and newly installed reinforced concrete support structures, while maintaining safety, minimizing disruption and ensuring construction progress.

To support these objectives, HBK deployed an integrated monitoring system combining fiber-optic sensing, multi-parameter instrumentation and automated data acquisition. The solution continuously measures structural behavior during excavation and converts complex data into decision-ready information, which helps engineers understand load transfer, verify structural performance and identify deviations at an early stage.

COWI designed the fully automated engineering analysis, in collaboration with HBK, a system that transforms monitoring data into actionable engineering intelligence. Automated analysis accounts for temperature effects, shrinkage and creep, enabling project teams to focus on the structural responses that matter most during critical excavation activities.

"We highly value the ability to monitor concrete columns with high-strength concrete class, using strain sensors, temperature sensors and humidity sensors. The sensors are used to monitor the concrete columns during the construction phase and mainly after, with an expected active lifespan of 120 years. Throughout this process, HBK's team provided fast technical support, visiting sites and conducting inspections as needed," highlighted Dorin Lungu, site manager for concrete works on the Trafikverket project.

"Major infrastructure projects require confidence in every decision made underground," said Mats Rydén, business development manager at HBK. “At Korsvägen, we're helping project teams move beyond data collection to engineering intelligence, providing the right product needed to manage risk, maintain progress and verify structural performance in one of Sweden's most complex urban construction environments.”

The monitoring system supports safe and efficient excavation with continuous visibility into structural behavior throughout construction. Through a combination of fiber-optic sensing, redundant instrumentation and automated engineering interpretation, project stakeholders can make informed decisions quickly and with greater confidence.

The solution has also been designed with the future in mind: instrumentation embedded within the framework will continue to support long-term structural health monitoring once the station enters operation, creating ongoing value for asset owners beyond project completion.