Constructed in 1975 and originally used as a cattle market, the Fernando Buesa Arena was converted into a 9,900-seat stadium in the early 1990s. It is now used for a range of sports events and serves as the home stadium to the local top-league basketball side Saski Baskonia.

Crowning the arena is an 81m diameter domed roof covering a surface area of over 5,600m2, which is an iconic feature of the city’s skyline having become an international architectural award-winning structure since its construction 37 years ago.

This meant that the roof could not be disassembled or destroyed in any way, but careful removal in one piece would be necessary for the works.

Tandem lifting was ruled out as no symmetrical load distribution arrangement could be found to attach two cranes simultaneously to the roof. It would also have sent project costs spiraling as the car park would be all but destroyed by the two crawler’s tracks.

The lift and heavy haulage contractor for the job, Spanish firm Usabiaga, had purchased a Liebherr LR 11350 crawler crane in July, and used it here on its debut lift. Usabiaga planned to use the LR 11350 to lift the roof from the stadium and transport it 80m to a temporary circular column structure that would support the roof until the capacity increase to 15,000 seats had been completed.

The LR 11350 was configured with a 130m boom, 830t of counterweight and 600t of ballast suspended at the rear of the crane, 30m from its slewing ring.

Then, with a 70m outreach, the crane was rigged to the load at 24 points using steel cables to minimise the deformation pressure the roof would be subjected to during the lift, and especially when subjected to traction force. The compact load traverse element, two metres in diameter, was designed especially for this lift.

At this point the 218t load—including rigging—was manoeuvred by operator Andrés Guerra while the crane was set in motion, ensuring the dome would be aligned with the 200-column temporary support structure while the crane slowly covered the 80m distance.

The LR 11350 had to slew 180° during this 90 minute manoeuvre, which could have been significantly longer using a tandem lift as the distance needing to be covered would have been 320m.

This strategy worked well, according to Usabiaga project manager Julio Herrero, who said, “After the dome had been moved, we only found minimal deformation of the lattice structure.”