Historical developments and innovations in the field of civil engineering contributed to the state-of-the- art structures that shape our transportation infrastructure network nowadays. By way of contrast, solving the mobility issues of the past, created a challenge in terms of conservation today as many assets are reaching the end of their technical, economical and functional lifetime [Hertogh et al., 2018]. Main challenge arises for public authorities which have to meet safety demands and satisfy user expectations in the context of aging assets, imperfect knowledge on their conditions, limited resources, increasing traffic volumes and threats from climate change. Determining when, what and how has to happen is therefore more complex than simply renewing or replacing assets [Polder et al., 2012; van der Vlist et al., 2015; Nicolai et al., 2016].Together with the evident challenges, the magnitude of the predicted increase of Maintenance, Renewal and Replacement (read: MR&R) projects creates a variety of opportunities. One of the opportunities, is to widen the perspective beyond the boundaries of a single asset. Creation of a holistic view and recognition of portfolio opportunities is considered to be key in realizing strategic and tactical objectives, improved alignment with other projects and realize savings due to a decreased need of resources and selection and procurement procedures [Ferns, 1991; Heising, 2012; Chen et al., 2013]. Realizing the potential while controlling the present challenges is however easier said than done. Public organizations within the Netherlands are currently facing serious difficulties in the implementation of their MR&R projects in a fit-for-purpose manner. Fit-for-purpose, in this sense, refers to choosing the best solution for a problem, given the others alternatives [Koops et al., 2017]. In order to investigate both the complexities and the possibilities of MR&R challenges, the main questions of this research is:”How can decision-making on the MR&R interventions of the emerging set of soon-to-be outdated assets be supported to configure assets in a fit-for-purpose manner?”Since the preferred solution regarding the development of a project is picked during the front-end development (read: FED) of a project, the research is focused on these preparatory phases. During the FED, the problems are assessed, a preferred alternative given the present requirements is selected and further defined before it continues to the consecutive project phases [Weijde, 2008]. To provide support on the related decision-making process, the research is guided by two main deliverables:1. Provide an overview of the main complexities of MR&R challenges which influence the FED process2. Develop a framework to support public organization in organizing their FED process to deal with their emerging amount of aging assets in a fit-for-purpose mannerThe overview of the main complexities public organization face during the FED of their to MR&R challenge was created by a combination of scientific and empirical research. Given the present body of knowledge on MR&R challenges, FED and decision-making complexities, a conceptual framework was created. This functioned as a pair of glasses through which multiple cases were analyzed. By investigating four MR&R cases of Rijkswaterstaat, the Municipality of Amsterdam and the Province of North-Holland individually and jointly, a set of 20 challenges emerged. Altogether, these challenges influenced the opportunity of public organizations in the creation of fit-for-purpose project, portfolio or program configurations during the FED procedure.To create a framework which indicates how to deal with these challenges, seven decision-making dilemmas were identified. These dilemmas indicate the opportunities executive authorities within public organizations have in aligning their FED process to their perceived complexities, requirements and resources. The red cluster marks the dilemmas which influence the physical solution space of MR&R challenges, whereas the dilemmas in the orange cluster determine the design of the FED procedure. Since the opportunity to review and revise made decisions applies on both contextual and procedural dilemmas, the agility dilemmas is present in both clusters.In the end, public organizations in charge simply have two choices: simplification or complexification of the FED process. To deal with the emerging set of soon-to-be outdated assets, the process may be kept simple and foreseeable, but the opportunity to create asset transcending benefits is small. On the other side, an organization may decide to deliberately complicate the configuration process by increasing the amount of elements and related considerations. Given the developed decision-making framework, there are seven options to realize potential integrated benefits. during the FED procedure. With every dilemma, decisions to either simplify or complicate the FED process may be made, which create the opportunity for a public authority to adjust the configuration process to the present requirements, complexities and resources. Observance of the cases and the afterwards validation of the framework however pinpointed the risks of increasing the complexity of the FED process. For example, creation of a separate program and related procedures to deal with the MR&R challenge may result in a reluctant attitude of the involved staff and create an unforeseen amount of interrelations with other divisions in the organizations. Ifthe amount of components and actors involved in the decision-making process increases, also a greater span of control is demanded [Leijten, 2017]. Manageability issues due to the increase levels of complexity may therefore hamper the overall FED process. Therefore, using the developed framework should help decision-makers in public organizations in finding a balance between the potential to create certain benefits and the risk of making the process too complex.In order to improve the validity of the developed decision-making framework, it was first tested in an existing case of Rijkswaterstaat by conducting an imitation experiment. Based on the conditions of the case, decisions on the dilemmas in the framework were made and translated into a FED process. Next to the imitation experiment, an expert review on the framework was conducted. In the presence of representatives of the Municipality of Amsterdam and Rijkswaterstaat, the framework was tested on its completeness, functioning and usability. In the end, both validation incentives confirmed the added value of the decision-making framework as it provides the opportunity for public organizations to align their MR&R challenge and objectives with a FED process design.

The beach adjacent to the Tasikoki Wildlife Rescue and Education Centre is one of the many beaches worldwide suffering from coastline recession. This loss of coast has a negative impact on the environment, local society and ecology. In general, shoreline retreat is caused by sea level rise (SLR) and erosion. The main objective of this research is to determine which factors are causing recession at Tasikoki beach and consequently which solution would be best in terms of mitigating coastline recession and protecting the hinterland from flooding. A Building with Nature (BwN) design philosophy has been considered to utilise natural processes instead of traditional ones, creating benefits for society and nature. Additionally, a model will be created in Unibest to substantiate and test the final solution.
The research first aimed to describe the coastal characteristics, ecosystem and societal system of the Tasikoki coast. This mainly consisted of a desk-study which was based on literature, but also of examining the surroundings and talking to locals. This study revealed amongst others the significant contribution of climate change on the shoreline retreat at Tasikoki beach.. Among the stakeholders, a major blocking power is absent. Nevertheless, an engagement plan is written to explain the local fishermen how they will benefit from the potential solution in order to prevent resistance. After gathering this general information to form a first impression, more location specific data was required to draw conclusions and setup the Unibest model. Every part of the required data has their own measurement method or source, using handmade measuring equipment, sonar GPS, sediment sieves and data retrieved from wind and wave models.
After a thorough analysis on the wave and wind climate and the surroundings of the Tasikoki coast, it could be concluded that the dominant wave direction is coming from a direction of 164˚ north. This determines the dominant sediment direction, which is thus propagating northward along the shore. Next, the direct coastal retreat due to SLR was calculated by using the Bruun-rule. Based on calculations and aerial image analyses, it was concluded that the two tidal inlets present at the Tasikoki coast play an important role in the erosion patternThe four main nearshore (CST) processes impacting the Tasikoki coast are wave impact, long waves, turbulence and avalanching/sliding. During the research, multiple possible solutions have been investigated which could mitigate the coastline recession. Based on a multi-criteria analysis, it was decided that a Biorock-based solution would suit the Tasikoki case best. This is a permeable submerged breakwater with a low current running through a steel frame to dampen waves and enhance nature at the same time.. A submerged breakwater was modelled in Unibest at Tasikoki beach. The result was positive. The structure traps sediment and causes more accretion along the coast than the length of the structure itself; functioning like a ‘sand engine’. At last a detailed implementation and monitoring plan was written, multiple scenarios are considered to make the solution more future-proof.