According to alliance manager Pim van Schaijk of the Directorate-General for Public Works and Water Management, the decision was taken after more information about the existing structure emerged while drafting more detailed designs. The underlying concrete beneath the asphalt deck appeared not to be as bumpy as first assumed, requiring less infill concrete to create an even deck.

What’s more, the stringers appear to possess a greater residual capacity. In view of the fact that the preferred initial solution could not be implemented without impacting the bridge’s weight either, resurfacing is indeed a feasible option. This will also be far easier than cutting the old surface out and removing it from below once the new deck has been laid. Cutting through the supports, and removing and gathering the pieces of deck at a great height working from floating pontoons would have presented serious challenges for the construction workers.

A workable layer of B65 concrete will be laid on the Hollandse Brug. Steel dowels will be used to connect the old deck. A total of 100,000 dowels will be used on the bridge, amounting to around five per square metre. The alliance is examining ways to reduce this number and automate the fitting process, so that each dowel doesn’t have to be drilled in and attached separately.

The new approach will not change much for heavy goods traffic, which has been barred from passing over the bridge since the end of April. Once the bridge is released for use, Strukton and Reef will not have to continue working to remove the old deck for another six months. But because the new design requires further elaboration, it will take some time before implementation can commence.

Strukton is currently removing the centre barrier. Van Schaik estimates that reinforcement operations will cost around €10 million. This represents savings of at least €5 million in comparison with the initial repair option.

Source: Infratech, 30 November 2007