Posts for traffic gantries drilled 'remotely'

The 4-day closure of the A16 Rotterdam over the long Ascension weekend was used to carry out a wide variety of work on the project. For two days, Kandt funderings- en aannemingsbedrijf BV was busy day and night drilling LEKA piles with grout injection for four new traffic portals along the existing route of the A16. An intensive job, during which some of the piles were even drilled from the A16 over the 5.5 meter high noise barrier. 

During the Ascension weekend, a total of 12 LEKA piles were drilled with a diameter of 457 and a thickness of 10 mm, in lengths of about 20 meters. "It involved the foundation of four traffic portals," says Jeroen de Bruin of Kandt foundation and contracting company BV. "For all four portals, two foundation piles had to be installed in the outer verge and, for two portals, also two piles in the middle verge. The difficulty was in drilling the LEKA piles in the outer verge over the noise barrier. So the posts are behind the noise barrier, while you can't get there with a machine. We drilled them from the A16 over the noise barrier with a specially designed machine. It required skill from our staff and special equipment. Everything had to be done on instructions via walkie-talkie communication. Anyway, if it had been easy, we wouldn't have been there," Jeroen says with a laugh.

Kandt Special Crane

Space was limited here because of the slope to the underlying road network. Therefore, a crane built by Kandt Special Crane was used. "It is basically a hydraulic sheet pile rig, but modified with special components to be able to drill with it," explains Jeroen. "The drilling motor is suspended from the boom of the rig, which makes it possible to install piles in hard-to-reach locations and/or at a greater distance. Because we also had to bridge the height of the noise barrier, the piles in the outer verge were drilled in two parts. First, we drilled away the bottom piece, then a so-called backing strip was placed on it with locking lance on which the top piece was set at right angles. Then our certified welders connected both parts and we were able to drill the pile further to depth. Finally, all the hollow spaces were filled with a grout mixture. And so we repeated this exercise seven more times in the outer verge."

Mobile grout plant

Since the four portals are some 200 meters apart, Kandt foundation and contracting company BV had rigged up a complete mobile grout plant, including container and grout mixing plant. "We were thus able to move all the necessary equipment quickly. It was just a matter of disconnecting the hoses from the KSC and moving the water container and we were already ready to install the next LEKA piles. After drilling the LEKA piles, we burned them to elevation and fitted them with a reinforcement cage. Steel angle lines were then welded to them, as support for the precast concrete elements of the new portals to be installed later. RvR Betonpomp Verhuur then filled all the piles with concrete." Kandt BV incidentally drilled the piles in the center medians in one piece with a regular transit rig. All in all, according to Jeroen, quite a job, in between all the other work at De Groene Boog. "Thanks to good coordination and understanding of each other's work, we finished well ahead of schedule."

Kandt BV, by the way, is a familiar face on the A16 Rotterdam. "In earlier phases, we have already vibrated quite a few tubular piles into the ground as foundations for the noise barriers, among other things."