The construction and installation of the Jan Linzel Viaduct over the A4: a precision job of great magnitude

Work on the tow-bike viaduct in The Hague is nearing completion. The viaduct runs across the A4 between the Ypenburg and Prins Clausplein interchanges. The total length of the bicycle viaduct - called the Jan Linzelviaduct - is no less than 330 meters long. 

Develop

Because of its length, the viaduct consists of nine sections. These were constructed in steel structures by Hillebrand and come to rest on eight concrete supports installed by Dura Vermeer. "It is a very intensive project. In a relatively short period the whole engineering and production process had to be set up, with the closure of the A4 as a sacred deadline," says Willie Lievense, project manager at Hillebrand. Putting the four sections in place over the A4 required thorough preparation, which Hillebrand carefully worked on with several teams for a long time. "Good preparation is half the battle. Especially when you notice the smooth cooperation between main contractor Dura Vermeer and us as specialists within bridge construction. If you complement each other, put in each other's strengths and value each other's added value, you achieve wonderful end results."

Placing the viaduct sections was quite a job: as many as 4 of Mammoet's 7 "heavy boys" were at work at the same time. Including a 750-ton crane, the largest mobile crane still allowed on the road.

Produce

In addition to the great cooperation with Dura Vermeer, Lievense also praises the entire Hillebrand team that worked on this project. Hillebrand has two large production facilities on the waterfront, providing the necessary capacity for this project. "There are as many as 35,000 man hours in production alone. The challenge was mainly in creating the slightly curved shape." Lievense explains: "You have to deal with factors such as the bridge's own weight, gravity and pressure load, so you already have to achieve a greater curvature in the production process than the one you ultimately want to achieve. That involves a lot of engineering." The workshops in Middelburg and Vlissingen worked with an elaborate mold 54 meters long. Using this mold, a kind of tube of hull plates with internal stiffeners was created. "It may seem like a matter of welding plates together, but it takes a lot of know-how and experience to arrive at a strong whole."

Transport

"Transporting all these deviating pieces and chunks has also been quite a challenge. That's where partner Mammoet played an important role. Together with them we examined all kinds of options. In the end, it was decided to hoist the enormous parts onto a barge with heavy cranes from Middelburg and Vlissingen and sail to Schiedam. There the parts were lifted from the ship and driven to The Hague at night with special transport trailers. At the destination, our people were ready to assemble the bridge parts."

And of course places

Sections A and B were installed above the highway lane on the first night. The second night, the two largest pieces were assembled running above the highway's entrance and exit lanes: bridge section C of 54 meters and 160 tons of weight and bridge section D of 46 meters 130 tons of weight. "Such weight requires large equipment," says Lievense. "So four heavy mobile hydraulic telescopic cranes were deployed (one 500-ton, one 700-ton and twice a 750-ton crane). A precision job of great magnitude, in other words. Then when everything literally falls into place and proceeds safely, it gives an extremely satisfied feeling." The remaining five pieces run alongside the highway and will be assembled in the final phase. After that, of course, the bridge will be completed by Dura Vermeer.