Knowledge Continuity Aspects in Designs and Contracts of Dutch Storm Surge Barriers

The infrastructure we build is increasingly complicated and automated. After it is designed and constructed, it needs to be maintained and updated to sustain its functioning for far longer than the careers of its designers and builders. Continuity of engineering knowledge is necessary to make future updates and adapt to changing demands, conditions and technology in a safe and reliable manner. The Dutch storm surge barriers protect the low-lying hinterlands from flooding during extreme weather events. Each of the six barriers managed by the Directorate General of Public Works (Rijkswaterstaat) was designed at a different time, to different requirements, and using different types of contracts. This has resulted in six unique structures, some of which use systems and components found nowhere else. In 1997, the Maeslant Storm Surge Barrier was completed, pioneering the use of Design and Construct contracts for major hydraulic structures. Experience with maintaining this hallmark structure through its first decades of operation provides a valuable opportunity to reflect on the effect of contracting- and design choices. Little work has been done to evaluate different contract types on the basis of delivering long-term maintainability and reducing the knowledge continuity challenge. This study views the Maeslant Barrier in the context of the earlier storm surge barriers with regard to facilitating knowledge continuity through design. It was found that the interdependent behaviour of subsystems in a high-reliability structure results in a notable increase in engineering complexity, especially in the control systems, increasing the challenge of achieving knowledge continuity. Examining the knowledge flows in a design-and-construct contract shows several advantages, but also that it does not naturally facilitate attention to important but less obvious aspects of maintainability, such as those related to knowledge continuity.