This research aims to identify the underlying mechanisms of the cost of rework related to constructability in Dutch marine infrastructure projects. Despite extensive previous research on the cost of rework, and constructability, the underlying mechanisms within executed projects in the Netherlands have not yet been observed from research. Notwithstanding the thorough previous research, indicates a need to identify the prevailing underlying mechanisms. This research addresses the following main question: What are underlying mechanisms for managing cost of rework related to constructability in Dutch marine infrastructure projects? The known underlying mechanisms for managing the cost of rework related to constructability were derived from the literature. These mechanisms were verified and extended through exploratory semi- structured interviews. The interviewees were senior experts from a client company, a design and engineering firm, and a contractor. Besides, the applied and unapplied mechanisms in Dutch marine infrastructure projects were observed from two case studies. The case studies included further semi- structured interview sessions. The findings from the three sources introduced themes regarding the mechanisms for constructability inclusion. The themes included a set of related mechanisms, which addressed the main research question. The inclusion and application of these themes in the project could minimise the cost of rework related to constructability in Dutch marine infrastructure projects. The most pertinent themes caused the changes and rework observed in the case studies and are indicated as manageable by the design and engineering firm. The identified themes were as follows: 1) extensive transfer, verification, handover, and control of knowledge, documents, models, requirements, needs, and products, 2) inclusion of experienced expertise or knowlegde (early) in the process, and 3) stick to the plan and process by all stakeholders after awarding. Limitation of the research were only two case studies, digital interview sessions, and missing quantification of the mechanisms' contributions and relevance. Some interesting results from this study were the unwillingness to learn, improve, and share previous insights and experiences of person in the Dutch marine infrastructure sector. The diverse perspectives, current market developments of the project approach and contracting, and the human contribution and obstruction were additional findings of this research. The recommendations for practice align with the answer to the main research questions. The most relevant recommendations for practice are the extensive transfer, verification, handover, and control of knowledge, documents, models, requirements, needs, and products, and sticking to the initial plan and process by all stakeholders after awarding the project. Recommendations for further research are 1) to test the validity and causes of the newly identified mechanisms; 2) to identify individual contributions and obstructions to the project, and 3) to quantify the effect of the mechanisms on scope, time, money, quality, personal health, and safety.

The Netherlands is a densely populated country with a congested road and railway network. Therefore more and more highways are widened and expanded. These wider highways create a demand for bridges which are suited for longer spans. These bridge solutions should constructed with a minimum of hindrance for other traffic. Rijkswaterstaat, also wishes to reduce the number of intermediate supports so the space underneath a viaduct can be used more freely. The currently most used solution to build a highway overpass without disrupting the traffic too much is a concrete viaduct consisting of prefabricated prestressed concrete bridge beams. But for spans longer than 60 meters those beams become too long and too heavy for transport by truck to the building site. Therefore the existing bridge solutions are reaching the maximum distance to which they can be built. The primary goal of this report is to find a concrete bridge solution with which it is possible to construct longer bridge spans in prefabricated concrete up to 100 meters. With such a bridge solution it is also possible to span a waterway or a small river in the Netherlands. A beam bridge in which the beam is composed of three parts is the most suitable solution to build these longer spans in prefabricated concrete. This solution can be constructed with relatively little hindrance for the other traffic. This solution is also relatively flexible in the shapes of bridge decks that can be constructed, skew bridges and wide bridge decks are both possible. The design of this beam bridge is extended and analyzed with a more detailed calculation. A bridge span of 100 meters is possible with a construction height of only 3 meters. This relatively slender design is possible because high strength concrete is used and because the bridge deck is designed to spread the traffic load efficiently over the full width of the bridge deck. The beam parts of this bridge can be transported by truck to its destination.
A rough cost estimation shows that the designed solution is expensive compared to existing concrete beam bridges, but it is also possible that the designed solution has a lower cost price compared to existing solutions in steel. It is advised to continue the research to and development of the bridge design because of the possible lower cost price and because with this design, bridges can be constructed which currently cannot easily be constructed with the existing solutions.

The construction method of an overturning caisson is reconsidered. This particular self-floating caisson was applied for several caisson quay wall projects over a century ago. After the year 1914, the design was abandoned. After this time, rectangular caissons became more economical due to higher qualities, simplified formwork and easier transport. However, the caisson geometry allows efficient material use and a relatively low draught during transport. When the concept is considered for current quay wall projects, these benefits are still present. However, the magnitude of these benefits reduced significantly. When other aspects, such as construction technologies are included, the remaining economic benefits are estimated to become negligible. The economic feasibility of an overturning caisson could therefore not be demonstrated.