Renovation and replacement (R&R) projects in public infrastructure are becoming increasingly complex, due to factors such as scope uncertainty, operational constraints, and the involvement of multiple stakeholder interests. Prior research has shown that for a successful delivery of complex projects it is essential to award contracts based on quality aspects, such as the contractor’s ability to manage complexity, rather than relying solely on price.

However, there is limited empirical evidence on the extent to which public clients translate project complexity into award criteria. This study addresses that gap by examining the case of ProRail, the Dutch railway infrastructure manager, and its use of award criteria in recent R&R tenders. It aims to analyze to what extent project complexity is translated into award criteria for the procurement of these projects. The research combines qualitative insights from interviews on perceived project complexity with a quantitative analysis of the award criteria and their weightings in four recent ProRail R&R tenders.

Findings reveal a partial but positive relationship: in more complex R&R projects, ProRail uses more project-specific quality criteria that are related to project complexity. Projects that were perceived as less complex relied more on ambition-related award criteria and price. Interview participants also mentioned that at ProRail technical complexity was addressed through strict requirements and not through award criteria, while organizational and environmental complexity were more translated into award criteria to create differentiation between bidders.

The research offers a first empirical foundation for understanding how a public client incorporates project complexity into its procurement practices. Although this study focuses only on ProRail, its findings and recommendations are relevant for other public infrastructure clients and can serve as a basis for future research into the alignment between project complexity and procurement strategies.

The scale and complexity of projects in the construction sector have grown significantly in recent years. Larger projects typically result in worse performance, including overspending and delays in the calendar.
This research focuses on identifying and analyzing Early Warning Signals (EWS) to mitigate schedule delays during the design phase of infrastructure projects managed by Sweco, a consultancy company in the Netherlands. The primary aim is to explore how effectively EWS can be used to identify potential issues early and prevent project delays.
The research begins by assessing the current knowledge and application of EWS among project managers, controllers and directors at Sweco. Initial findings indicate that while most participants have a basic understanding of the concept of EWS, they do not actively use or recognize it in their daily workflows. Their awareness of these signals primarily stems from gut feelings and extensive experience rather than systematic identification and application.
To identify the most relevant EWS, the study combines insights from existing literature with practical experiences shared by Sweco experts. This process involves creating a comprehensive list of potential EWS, which is then narrowed down and prioritised based on their perceived impact and likelihood. The prioritisation is similar to a risk assessment method, considering both the probability and potential impact of each signal.
The study examines how to measure data related to the signals and proposes measures on how to handle those EWS better. Some of the suggestions include establishing clear working agreements, balancing formal and informal communication, enhancing collaboration through workshops and visual tools, and leveraging advanced technologies like AI and BIM. The study further emphasises the importance of continuous client communication, internal quality checks, and ensuring appropriate expertise for project tasks.
The research provides a comprehensive framework for identifying, measuring, and managing EWS to improve project outcomes and reduce schedule delays in infrastructure projects. The findings emphasise the need for systematic approaches and technological integration to enhance early warning capabilities and project management practices. By implementing the recommended strategies, Sweco can better anticipate potential issues, make informed decisions, and ultimately deliver projects more efficiently.

Keywords: Early Warning Signals (EWS), schedule delay, design phase, infrastructure projects, project management, measurability, prioritisation

Construction accidents are known to occur often; in 2022, there were 129 accidents in the Netherlands for every 100,000 workers . Beyond the tendency to place the responsibility on employees, this study investigates the impact of client involvement in enhancing safety performance. The majority of safety research focusses on the building phase, indicating that client influence decreases as projects progress. The study highlights 43 crucial client responsibilities with a focus on pre-construction phases, specifically in the Planning, Inception, and Feasibility; Design, and Procurement and Tendering phases. Moreover, Semi-structured interviews reveal differing practices between infrastructure and oil & gas projects, providing the opportunity to learn from these differences and highlighting areas for improvement, such as establishing stricter safety objectives, early contractor involvement, and enhanced knowledge sharing. The findings suggest that optimizing client roles in pre-construction phases can significantly enhance safety performance in construction projects.

As concerns about climate change increase, which can harm the environment, all kinds of businesses face a challenge called sustainability. In the construction sector, one pathway to greater sustainability is designing and constructing buildings with low carbon emissions. Some researchers have explored this challenge by investigating the portion between embodied and operational carbon, as well as the methodologies for calculating each type of carbon emission in buildings. Having an understanding of the design's performance against this challenge will provide more opportunities for design optimization. However, there is limited literature discussing methodologies to optimize whole-life carbon emissions, especially for apartment buildings in the Netherlands. This thesis project aims to fill this research gap by closely examining the practical relationship between embodied and operational carbon and by achieving optimized building designs to minimize whole-life carbon emissions. The scope of this thesis includes analyzing embodied carbon from stages A1 to A5, operational carbon at stage B6, focusing specifically on studio apartments located in the Netherlands. To achieve the aim of this thesis, which is to explore the relationship between embodied and operational carbon in apartment buildings located in the Netherlands, several key steps were undertaken. This study began with a comprehensive literature review and analysis to define factors and methodologies for calculating both embodied and operational carbon emissions. Subsequently, a case study was conducted using a simplified model in Excel and IES software to quantify these emissions. Optimization strategies were then implemented using Rhino 7 and Grasshopper. A detailed framework was developed in Rhino 7 and Grasshopper to guide optimization and analyze the resulting data. Finally, validation and evaluation of the framework and its outcomes were conducted through expert interviews. The findings yielded several critical insights. For instance, certain materials with higher embodied carbon can lead to lower operational carbon, while those with lower embodied carbon may result in higher operational carbon. Moreover, increasing thickness can effectively reduce operational carbon and contribute to overall reductions in whole-life carbon emissions, up to Rc 4; beyond this, the benefits diminish. Furthermore, materials with high embodied carbon above Rc 4 tend to increase whole-life carbon emissions, despite potential reductions in operational carbon. Lastly, each Rc of the façade has its own optimal façade opening, and window frame material only influences a small amount of the embodied carbon and has no influence on operational carbon. However, this result is based on Dutch circumstances and specific MEP inputs. Therefore, these results will differ if different locations and MEP inputs are used. Through this framework, designers are provided with practical guidance to achieve optimal solutions in apartment building design. Additionally, this framework has already been tested by expert respondents in this field, as detailed in Chapter 5. Recommendations for future research include expanding the scope to whole entire apartment (from foundation to roof) and integrating financial considerations into optimization strategies.

The Dutch government aims for a fully circular built environment by 2050, transitioning from a linear to a circular economy. This involves establishing construction hubs, divided into circular hubs (focusing on closed-loop material chains) and non-circular hubs (focusing on efficient transportation). Currently, only a small fraction of construction and demolition waste is reused, making the role of circular construction hubs crucial.

This study investigates how to stimulate the realisation of urban mining hubs in the Netherlands. The primary research question is: How can the realisation of urban mining hubs in the Netherlands be stimulated? Data was collected through a literature review and semi-structured interviews with key stakeholders in the construction sector.

Findings highlight the undefined role of hubs within the urban mining process and the advantages they offer, including resource conservation, financial savings, and employment opportunities within a circular economy. Barriers include insufficient material supply and demand, inventory uncertainties, and inadequate legislation. An actionable framework was developed, consisting of three phases: initiation, optimisation, and expansion, with a focus on innovation, education, and collaboration among stakeholders.

This study examines improving the documentation and application of lessons learned in tender processes within the Dutch construction sector, focusing on Royal BAM Group. Despite the need for effective knowledge management, challenges like fragmented knowledge sharing and inconsistent documentation persist, limiting organizational learning. Using Social Network Analysis (SNA) and Root Cause Analysis (RCA), the research identifies key organizational, technological, and cultural barriers impacting knowledge sharing. The study proposes a GIS-based application to enhance access to lessons learned across departments. Recommendations include short-term actions and long-term strategies to formalize documentation and foster a learning culture, aiming to optimize future tender projects.

In the construction of subsoil structures, a common challenge is the presence of a high groundwater level in combination with the absence of a naturally impermeable layer or an environment susceptible to settlements due to lowering the groundwater level. To overcome this issue, a building pit with an underwater concrete floor (UCF) can be constructed. The UCF ensures structural rigidity and allows for the building pit to be drained such that a dry and safe subsoil construction site is obtained.

The objective of this thesis is to investigate how design efficiency of underwater concrete floors can be improved. In an effort to reduce material usage and achieve cost-effective structures, the following research question was stated:

“What is the influence of design parameters and how can parameters be adjusted to improve design efficiency of an underwater concrete floor, and to what extent can the addition of fibre reinforcement contribute to this optimization?”

A parametric model was developed to provide insight to the sensitivity of parameters and their impact on design resistance. Furthermore, the model was utilized to examine under what circumstances potential material savings can be obtained by implementing fibre reinforced concrete in UCF’s. This was accomplished through the evaluation and comparison of the minimum required thickness based on bending moment resistance in various scenarios, for both UCF’s and steel fibre reinforced UCF’s (SFUCF).

Results obtained with the parametric model established that, in order to enhance the bending moment resistance of an uncracked UCF, increasing the nominal thickness becomes relatively more effective compared to increasing the concrete strength class for higher normal forces. When utilizing a compression arch to obtain bending moment resistance, the implementation of ribbed tensile elements or an increase in nominal thickness are found to be the most suitable methods for increasing resistance. For enhanced shear force resistance, increasing the nominal thickness over the concrete class provides relatively more additional resistance for slender UCF’s. The results found that through the application of ribbed piles, most punching shear force resistance can be obtained.

Three use cases for a SFUCF were identified using the parametric model. When centre to centre (c.t.c.) distances larger than 4.4m are applied in combination with a substantial normal force, significant material savings of up to 0.3m thickness are possible, which equates to a reduction of material usage by 30%. For situations where the effective height of the compression arch is small, it was also found that material usage could be reduced by 30%. Perhaps the most significant use case for a SFUCF is when the normal force is close to zero, and additional normal force cannot be obtained through membrane action. In these situations, the application of a SFUCF can make an otherwise near impossible project feasible.

As a new design approach, a cost-based optimization tool was developed using the parametric model. An already executed UCF was evaluated using the tool, it was determined that a more cost-effective design could have been achieved, with potential savings of up to 30% in costs.