A16 Rotterdam, the new connection between the A16 at Terbergseplein and the A13 at Rotterdam The Hague Airport, is being constructed by De Groene Boog on behalf of Rijkswaterstaat. Part of the work involves the construction of the Rottemerentunnel. With a length of 2,235 metres, this tunnel will be half buried in the Lage Bergse Bos. A formwork solution from Hendriks is being used for the construction of the tunnel. We discussed the choice with site manager Sander Tetteroo.
Sander is part of the team at De Groene Boog, a construction consortium in which BESIX, Dura Vermeer, Van Oord and TBI companies Croonwolter&dros and Mobilis have joined forces. As chief site manager, he is primarily responsible for the construction of the Rottemerentunnel. To construct this, sheet piling was first installed, after which a deep trench was dug in which the tunnel could be sunk. The floor of the tunnel was then constructed by divers using reinforced underwater concrete. "This was the foundation on which the tunnel had to be built," Sander Tetteroo begins. "A considerable challenge, because the tunnel floor has an undulating profile."
Despite these differences in height, the connection between the floor and the wall must, of course, be completely sealed and watertight. A number of subcontractors from the United Kingdom and abroad were invited to come up with a solution that would enable the tunnel to be built. "We did not give them any fixed parameters, but left the suppliers completely free to come up with their own solutions. Hendriks was also invited to participate; the company was one of four companies that remained on the shortlist.
“We held extensive discussions with these companies and asked them to submit a quotation for the solution they had devised. Our starting point was always to choose the ‘best for project’ solution.” The proposed solutions were assessed by a team consisting of a work planner, formwork engineer, purchaser and site manager. “We had made it clear from the outset that we wanted to work with a partner who thinks along with us; a proactive party that is also willing to share its expertise. The quotations were assessed on the basis of innovation, safety, completeness, man-hours required, sustainability and low environmental impact (Environmental Cost Indicator).”
“After receiving the quotations, the parties were given the opportunity to present their solutions and exchange ideas with us about their approach. All in all, we invested a lot of time in the quotation phase. With this approach, we expected to be able to make further gains in the rest of the process. That turned out to be the case.” The decisive factor here was the weekly cycle. "We wanted to know how many man-hours the four parties would need to deliver their solutions in order to meet that cycle," Sander continues. "After assessing the quotations on the basis of the six selection criteria, Hendriks emerged as the party that offered the best overall package. We then took the next step with them."
The next step consisted of further engineering the proposed solution: a mobile formwork system for casting the central tunnel channel, the outer walls and the tunnel deck. “In a one-week cycle, the tunnel formwork is poured every Friday, after which the concrete hardens over the weekend. On Monday, the formwork can then be removed, moved on, cleaned and adjusted so that the reinforcement can be installed on Tuesday. And thanks to smart innovations such as a flexible centre pin hole, there is little or no work to be done on the reinforcement when we start forming. This is a great example of the collaboration between Hendriks and the client, exactly as we had envisaged at the start of the project.”
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