Waal bridge: Renovation of a historical steel bridge

Engineering the concrete deck

The concrete deck lost its load-bearing capacity due to de-icing salt corrosion and needed to be replaced. The main challenges were meeting weight limits, ensuring durability, and aligning with the steel structure, which had deviations from old construction tolerances, historical bombing during WOII, and reconstruction. Our engineers designed a new concrete deck with the smallest possible thickness that is structurally safe and not compromising the existing steel structure.

Fast-tracking the delivery to minimise traffic impact

Meeting the increasingly stringent requirements in terms of both the cover and load-bearing capacity presented a challenge. Taking into consideration the longitudinal and transverse steel beams, the new concrete deck now consists of more than 350 prefabricated panels which were assembled on site.

Every section is, in combination with repair, grid blasting and metallisation of the steel structure, completed in only one week. The usage of prefab panels also allows for good quality control while reducing construction time. This, in combination with the use of a high-quality concrete mix, ensures durability will not be compromised. The result: a thin concrete deck of 190 millimetres, maximum reliability and minimal traffic hindrance during construction.

The steel structure could be assessed and mended in a short period of time thanks to a strict preparation process in which the expected damages and standard repairs of the existing steel structure were specified. A carefully managed, collaborative process between the consortium and Rijkswaterstaat meant no unforeseen delays occurred during the replacement of the concrete deck.

Coordinating structural safety

Safety is essential across every stage of a bridge upgrade: the team worked to ensure the structural safety and guarantee safe crossing throughout the construction works. Although the role of Structural Safety Coordinator during construction was assigned to the contractor, the role was in this case fulfilled by Arup.

During preparation phase, Arup constantly checked and assessed the contractor’s workplans to guarantee the bridge’s structural safety, creating a more agile process with constant reporting back to Rijkswaterstaat, who remained responsible for the global structural safety. This set-up enabled a quality information flow, creating an effective, trusting collaboration to ensure the timely delivery of this safe bridge.