Knackpunkt Logistik: Lösung Lean!

It is a demanding tunnel and specialist underground engineering project: In Cessy, France, Implenia is building an underground network of tunnels that connects to the existing tunnel of the CERN particle accelerator. Access to the tunnels is provided via an 80-metre-deep shaft. As well as five buildings on the surface, the team is building a 46-metre-long cavern at the foot of the shaft, a 300-metre-long main tunnel with a cross-section measuring 44 square metres, and four connecting tunnels to the existing tunnel.

Supplies via portal crane

Delivering machinery, equipment and concrete via a deep shaft makes logistics and its optimisation a core factor in the success of this project. A portal crane with sets of lifting gear for 15 and 50 tonnes was set up above the access shaft. It not only allows safe access for people, but also ensures the supply of materials, including large equipment and building materials, as well as concrete and formwork tools. Three cable drum attachments developed especially for this project can lift loads of up to 10 tonnes.

“We used the last planner system (LPS) to generate an overall plan for three weeks at a time,” explains Florent Baulat, Main Works Manager. “The tool allows each individual tunnel to be divided into work blocks, each with associated tasks. The logistics needs for each time period can thus be determined very accurately, and we can optimise all the tasks in terms of safety, quality and efficiency.”

In order to optimise the lifting and transport processes, the installations at the shaft head were planned so as to create a buffer zone. “The Lean approach really paid off for us!” emphasises Florent Baulat. “We were able to optimise the planning, structure tasks and control the lifting processes in the best possible way by organising the equipment used above ground.”

Greater safety and efficiency

When it comes to safety, too, the benefits of this approach are undisputed. “Thanks to the Lean construction tools, we are able to recognise risks and difficulties early and define clear, well thought out and standardised process steps,” explains Safety Officer Michel Leandri. “The fewer interfaces there are, the lower the risks. Detailed task planning makes it possible. Certain tasks, such as lifting or moving heavy loads, are conducted in a short time frame thanks to clever organisation, allowing the points of contact between machinery (excavation machines) and pedestrians (concrete engineers) to be limited. The result is maximum quality and safety.”