Pushing steel structures with precision at the Kirjalansalmi bridge

Koherent2024-06-222 minutes

The Finnish Transport Infrastructure Agency (FTIA) develops and maintains the state-owned road network, the railways, and the waterways in Finland with a yearly budget of EUR 2.1 billion. FTIA has contracted Kreate to build the 600-meter-long cable-supported Kirjalansalmi Bridge in Parainen, southwestern Finland. The first over 100-meter steel deck structure was successfully moved to its place by jacking. Koherent’s sensors provided data for monitoring and controlling the steel structure during the jacking.

The first push of a steel deck structure of The New Kirjalansalmi Bridge has been executed with extreme precision. The deck structure consists of 20 assemblies and was assembled on-site.

“The Kirjalansalmi Bridge structure and design are very rare in Finland. We followed the push of the huge steel structure closely with a digital monitoring system based on real-time and extremely precise measurement data provided by Koherent’s sensors. Pushing the first steel structure went well”, says Development Manager Rasmus Sainmaa at Kreate. “Thanks to all involved.”

Improving overall safety and transparency in Kreate's operations

Kreate’s professionals were able to continue the pushing operation of the bridge steel structure even in snowy, cold, and windy weather conditions with low or zero visibility.

”We observed the exact location of the structure through a digital mobile application. It is very important to know how much the structure moves and bends down during the pushing operation. If the structure bends too much or if unpredictable changes occur, we might need to interrupt the operation”, underlines Sainmaa. “Kreate’s bridge designers and engineers involved in the project can use the data to verify the bridges structural behavior. Koherent has further developed the system and improved reliability. Our trust in Koherent’s grid has grown during this project. We plan to use the Koherent grid also in our future projects.”

Koherent’s technology is based on radio interferometry. The data was visualized on a data model platform (BIM) and is stored for further automated data analytics. Koherent provides API for easy integration with partner visualization and analysis tools. The system is easy to install, deploy, and remove.

“We are proud that Kreate wanted to utilize Koherent’s measurement solution in this construction project. Our solution showed the bending and the exact direction of the steel structure with mm-accuracy”, comments CEO Kari Leppänen at Koherent. “We have learned a lot during this project and are happy to continue cooperation with leading experts in the industry as the building work progresses.”

Kreate’s professionals will still run two more deck pushes at Kirjalansalmi, all with position monitoring using the Koherent grid. Kreate has yearly 50-100 bridge construction projects.

Koherent also helps to monitor the structural health of the old Kirjalansalmi Bridge until the new bridge is opened for traffic.

Facts and figures in short – moving the steel structure

  • 100-meter long steel structure including 20 assemblies.

  • Time needed: 2.5 days.

  • Distance moved: 100 meters.

  • Continuous 3D monitoring with mm-accuracy.