Against the backdrop of central Paris, a Liebherr MK 88-4.1 mobile construction crane operated by the Ponticelli group of companies repaired a damaged art installation on the Pont-Neuf bridge and reinstalled the affected parts. The temporary artwork, 'La Caverne du Pont-Neuf' by the French artist JR, was created as a tribute to Christo and Jeanne-Claude's wrapping of the bridge, first installed in 1985.
The inflatable structure is around 120 metres long. In early June, violent gusts of wind and hail damaged parts of its outer shell. Ponticelli, a French lifting and industrial services company, was on site just a few hours after the damage to work out a technical solution together with the client. "As well as repairing the tarpaulin, we had to carry out a lifting operation safely in almost constant wind and under considerable time pressure," said Louis-Arthur de Quatrebarbes, head of the handling and lifting agency at Ponticelli.
The Pont-Neuf, the oldest bridge in Paris, leaves limited space for work and welcomes a large number of daily visitors. Load-distribution plates reduced ground pressure, while safety and traffic management measures allowed the operation to be carried out safely.
The team had originally planned to use a larger Liebherr mobile crane, but the tight conditions led to the MK 88-4.1 being brought in for the repairs. Its 45-metre trolley jib reached all the damaged areas of the structure, while the four-axle design made it easy to relocate from one side of the bridge to the other, where there was also storm damage. A short set-up time and a compact outrigger system further facilitated the work.
Crane features and night shifts
The crane cab had the additional benefit of being able to move at working height, giving the operator a clear view of the approximately 18-metre-high structure and of the rope access technicians. Boom-mounted spotlights ensured optimum illumination of the work area during night-time operations.
The repair work was carried out over four night shifts. Damaged fabric sections weighing between 200 and 400 kilograms were lifted and reattached in collaboration with rope access technicians. Because the site lies in a wind corridor along the River Seine, weather conditions were monitored continuously, and the crane operator and the rope access technicians communicated by radio throughout.
Before work began, the team performed site inspections, load calculations and collision analyses of the surrounding buildings, and a 360-degree test subsequently confirmed the planned crane positioning.
For Ponticelli, the project was more than a conventional lifting operation. Quoting JR — "The installation of the artwork is part of the artwork" — de Quatrebarbes said the crane was part of it too, and described the visually striking deployment of the MK crane as a magical moment.
With the Pont-Neuf deployment, the Liebherr MK 88-4.1 demonstrated its reach, compactness and flexibility in demanding inner-city projects where heritage conservation, confined spaces and a high level of precision come together.