Shell sections for Blankenburgverbinding connection pillarsMaximum safety guaranteed
Safety is a high priority for all construction sectors and infrastructural works in particular. The focus on safety often must be combined with a need for flexibility and speed. A good example of this is the shell sections developed by Hendriks precon for the construction of the pillars for the Rozenburg junction, part of the Blankenburgverbinding connection. As standard, these sections incorporate various safety features that make them stand out in the area of safety.
The construction consortium BAAK is constructing the Blankenburgverbinding connection under contract to the Directorate-General for Public Works and Water Management (Rijkswaterstaat). As part of Rotterdam’s main infrastructure, the Blankenburgverbinding connection provides for a robust network and better accessibility to the Rotterdam ports and the Rotterdam region. The new motorway (A24) with 2×3 lanes connects the A20 motorway at Vlaardingen (north shore) with the A15 motorway at Rozenburg (south shore). The Blankenburgverbinding connection will have a land tunnel, an immersed tunnel below the Scheur river delta (Nieuwe Waterweg shipping canal), a sunken connection to the A20 motorway and an elevated connection to the A15 motorway (Rozenburg junction). The A20 motorway will be widened up to the Kethelplein junction. The new motorway will open to traffic in 2024.
Varied pillar heights
Various viaducts will be constructed at the Rozenburg junction as part of the connection. A total of 31 in-situ poured pillars that vary in height and length will be required for these civil works. The 2-metre thick pillars vary in height from 2.38 metres to as high as 15.64 metres; the length varies from 7 to 9 metres. The sides of the pillars are semi-circular. Leonard Tonkens, Project Coordinator A15 Junction Civil Works: “To be able to achieve a semi-circular shape, multiple shell sections with a 1-metre radius were developed in close cooperation with Hendriks precon. These sections make it possible to pour pillars of various heights.”
Connection to panel formwork
The shell sections vary in height from 2.20 m, 2.65 m, 2.90 m, 3.40 m and 4.60 m. “These shell sections make it possible to construct semi-circular pillar sides ranging from 2 metres to a maximum of 15.80 metres in height. A key principle in the development of these shell sections was the need for a simple and seamless connection to the standard panel formwork we use,” says Leonard Tonkens. The coupling used by the panel formwork was therefore incorporated one-on-one into the connection of the shell sections.
Because the pillars vary in height from over 2 metres to almost 16 metres, the various shell sections incorporate numerous safety features. Leonard Tonkens: “The safety system is far-reaching: working and pouring platforms that are 90 cm wide protected by 2-metre high railings provide for a safe working environment. The platforms are accessed via (cage) ladders with anti-slip rungs. These are placed on the shell sections in such a way that when the sections are coupled this does not result in a single long ladder, but instead it is necessary to change sides on each subsequent platform. This limits the falling height in case of an accidental fall from the access ladder to a minimum. The platforms are located some distance from the upper edge of the shell section; this way the work is performed at a safe and ideal working height. Furthermore, this reduces the danger of falling into the formwork. In addition, everything possible was done to avoid loose parts from falling. For example, all shell sections are equipped with permanent lifting hooks, all nuts for the connecting pins are welded on, and the hatches and gates are implemented in such a way that while they can be opened they cannot fall out of their hinges. Furthermore, the fastening points for the struts are not attached to the difficult to reach shell sections, but at the outer edges of the platforms that are easily accessible.”