Tunnel construction: minimal construction time and tight planning

Lean construction is now fairly commonplace in construction. Long before this efficiency method made its appearance, however, the tunnel process was already 100% lean. "It's inherent in the tunnel principle: working in a train with a lot of repetition. I already know what will happen next Thursday on that job at that time."

Casco Bouw Nederland can handle all concrete systems, but tunneling has been its number one specialty since its inception in 2003. Director Jan Hokse can speak enthusiastically about it 'because it is such a fantastic system'.

Smiling faces

"You can plot out a project's entire schedule at the daily level," he says. "You make tight agreements with the braiders, the installer who lays the pipes and the concrete plant so that everyone knows to the minute where they stand. Discipline in tunneling is very high. Everyone has their supplies and people on edge and keeps their appointments, even when it is raining cats and dogs. When a tunnel process is running, with good experienced parties and a tidy construction site, you always see smiling faces. If a link does not work, the train gets stuck. We therefore only work with parties who are experienced in the tunneling process."

UPtown in Rotterdam.

Advisory role

"In preparation, we can also do a lot," Hokse said. "We can consult with the architect and structural engineer on stability, reinforcement quantities, suspension of balconies and the like. For example, we recently advised on a high-rise tunneling project where the structural engineer wanted to get the stability out of the elevator core. However, more ideal within this design was to get the stability from the junctions between the walls and floors, which is what we advised."

Beech Supply

What has taken off in recent years is beech supplies for interior finishing. Hokse: "We make sure that all the packages of the interior finishing are already in place before tunneling. Then we make the nave, the next day the box goes out and then the finishing work can start immediately in the stamp-free area. That's time-saving for the contractor and a big advantage of tunneling. When the tunnel is finished, you can also immediately install, for example, HSB façade elements with glazing so that you are wind and watertight. In 80% of cases, the masonry scaffolding also runs right along with our tunnel layer, so the mason can start quickly. Usually we use an interval of 3 or 4 building layers. You see, we do our best to make the construction process as efficient as possible."