Heinenoordtunnel is many thousands of drilled anchors and tons of steel richer

Rijkswaterstaat took advantage of the renovation of the Heinenoord Tunnel to provide the tunnel with a middle tunnel channel over two levels with an escape route and service corridor. The service buildings and anti-glare louvers above the tunnel entrances were also firmly addressed. For all these facets, Jos van den Bersselaar Constructie supplied the steel structures, which in turn called on Interboor Midsland as a BRL-certified company to drill the many thousands of anchors in the 55-year-old tunnel.

Surely the biggest operation of the renovation is the construction of the middle tunnel channel, a job that was completed last summer during an out-of-service period of just four weeks by construction consortium Savera III. "The middle tunnel canal was built with a prefabricated concrete wall that was driven in and in which we installed escape and service platforms along its entire length in the form of steel grid floors," begins John Verhoeven, project manager at Jos van den Bersselaar Constructie. To anchor the concrete wall and the grid floors, Interboor Midsland drilled over 3,000 anchors.

Heavy angle steels

During the construction of the middle tunnel canal in the 4-week out-of-service period, Jos van den Bersselaar Constructie and Interboor Midsland pulled together and followed the little train of the construction crew. "In doing so, we worked per section from top to bottom," says Wilko van Oosten, anchoring specialist at Interboor Midsland. "That started with mounting the heavy angle steels for anchoring the concrete wall to the ceiling of the tunnel, after which the construction combination could then drive in the concrete elements per section with special vehicles. To avoid hitting and damaging the existing reinforcement in the tunnel, we were not allowed to use diamond drilling in the ceiling, but used the technique of hammer drilling." Verhoeven adds: "Because that technique is less accurate, we provided four slotted holes in the corner steels, so that we always had an extra opportunity to place the two anchors. The time pressure was incredibly high; we couldn't afford any delays."

Oiled machine

After installing a section of concrete walls, the team from Jos van den Bersselaar Constructie and Interboor Midsland went to work installing the steel grid floors. "We had made a work platform to make all the provisions from top to bottom," Verhoeven explains. "So that meant first drilling the anchors for the upper platform, then the steel structure was assembled and we could lay the grid floor. Then the work platform was pulled forward again several meters so that we could make the escape platform. So together we moved through the entire tunnel like a well-oiled machine in three weeks. Seven days a week with two shifts a day. The great thing was that the mechanics from Interboor Midsland also assisted us with the construction of the platforms. The cooperation was really top-notch." Every few meters there is an escape door in the tunnel wall. At those locations, Jos van den Bersselaar Constructie provided heavy angle lines as additional approach protection. 

BRL-certified

Interboor Midsland is BRL-certified to install the anchors. "It is set as a condition by the Department of Public Works to be allowed to work on 'its' objects at all," says Van Oosten. "We have therefore taken on the task of testing the connections in practice and maintain the process certificate." The latter has not yet been fully completed, as both companies are still active on and around the tunnel. "For example, the service buildings are getting a makeover and will be fitted with a second skin, which will require a substantial steel structure. We will also convert the elevator shafts into stairwells. In addition, above the entrances we will realize the construction for the new anti-glare louvers. All these structures will also be anchored by Interboor Midsland with drilling and glue anchors in the existing tunnel structure."