The European energy system is significantly changing to restrict the rise in global average warming. There is a shift from fossil fuels to renewable energy sources, which resulted in an exponential growth of offshore wind energy capacity in the North Sea. However, the North Sea is already one of the most intensively used sea basins in the world and space is limited. Offshore wind farms are therefore increasingly constructed under less favourable conditions. On the one hand the industry is rapidly developing and the cost of offshore wind energy goes down, but on the other hand offshore wind farms are constructed at greater water depths and further from shore. This latter development counteracts the cost reduction achieved by the industry, but countries are forced to construct offshore wind farms under less favourable conditions in order to achieve the climate agreements.

In June 2016, Dutch transmission system operator TenneT proposed the Hub and Spoke concept. It is an alternative method to connect offshore wind farms with the onshore grid and makes the parameter distance to shore far less important. Basically, the concept combines offshore wind farms with interconnector cables. An artificial island is created somewhere in the centre of the North Sea which is surrounded by offshore wind farms, thereby being far away from the crowded coastlines while profiting from near shore conditions. The interconnector cables subsequently transport the generated electricity to shore.

Dogger Bank is the envisioned location for the Hub and Spoke concept. The area contains strong winds, shallow water conditions and is centrally located. However, the unique characteristics of the shallow sandbank make it also very favourable to a variety of species. The area is therefore appointed Natura 2000 territory and could cause major resistance from environmental organisations. The general consensus amongst environmental organisations is not yet known, but industry experts indicate this as the major reason which could stop the Hub and Spoke concept from being realised on Dogger Bank.

The objective of this research is to determine the optimal location for the Hub and Spoke concept in the North Sea. The concept feasibility has never been determined and it is not even certain if Dogger Bank is the most beneficial location, while the location contains a very large risk. Therefore, the site selection model is created. The model contains input data from metocean conditions and electricity markets, which makes it possible to calculate the feasibility of the Hub and Spoke concept for every location in the North Sea. The result is a contour plot with the net present value of the Hub and Spoke concept, which shows the optimal location in the North Sea.

The Hub and Spoke concept is divided into five components to determine the influence of certain conditions on cost or revenue and to compare the components between each other. The artificial island and offshore wind turbines are primarily influenced by water depth, while the subsea interconnector cost is mainly influenced by the cable capacity and length of the cable. The optimal location for the island and offshore wind farms with respect to cost is thus along the shallow coastlines or at Dogger Bank, while the optimal location for the subsea interconnector cables is determined by the minimum total cable length. This point is equal to the centre of gravity of the countries surrounding the North Sea and is located just above the Netherlands and Germany.

In terms of revenue, the wind conditions are normative for the production and revenue of offshore wind farms and interconnectors derive their congestion rents from electricity price differences between countries. Offshore wind farms generate most electricity in the northeastern part of the North Sea where the wind conditions are strongest. This negatively impacts the generated revenue from subsea interconnectors as the cable is used more often for offshore wind energy. Interconnector revenue of the Hub and Spoke concept is therefore lowest at locations with the strongest wind speed, but in total the highest revenue is generated. A comparison between these components for four various locations is presented in Figure 1.

XXX

Offshore wind farms are both in cost and revenue the major component in the Hub and Spoke concept. The optimal location is thus expected to be found in areas with shallow water depths and high wind speeds. Finally, each component with its cost and revenue has been determined and can be merged in the site selection model to determine the feasibility of the Hub and Spoke concept in the North Sea. See Figure 2.

XXX

It can be concluded that the highest net present value for the Hub and Spoke concept is situated along the coastline of Denmark and Germany. However, these locations are known to be very crowded and the reason to investigate alternative locations in the first place. Dogger Bank and the northwest of Denmark are two very interesting alternatives. Dogger Bank is very shallow with depths of 10 m, while the northwest of Denmark is slightly deeper with 20 m but contains roughly 10% higher wind speeds. Both locations are primarily free from other marine uses, although Dogger Bank is protected Natura 2000 territory and therefore contains a very large risk. It is therefore advised to construct the Hub and Spoke concept at the northwest side of Denmark.

Zutphen is a city in the Netherlands, located along the IJssel River and the nautical access of the Twentekanaal. Despite its beneficial location, Zutphen barely uses the inland waterways for freight transport. This lead to the objective of this thesis: To provide insight how a viable inland waterway terminal be realized in Zutphen’s business park De Mars to improve its freight connection.
After analysing the regional and local infrastructure and transport flows, it was found that the best opportunities arise for the development of an intermodal inland waterway transport (IWT) connection, including an inland container terminal in Zutphen. A reliable intermodal transport service can only be realized if the terminal operator has access to a sufficient and constant flow of cargo volumes to be transported. Cargo can only be attracted if shippers are willing to make a modal change.

A framework consisting of several analyses was presented to assess the feasibility of an inland container terminal in Zutphen. Based on input from these analyses, three technical designs of proposed terminal solutions were worked out. A terminal solution is considered to be feasible if a business can be found for a private investor. For each of these alternatives, a financial assessment was worked out to determine whether a business case can be found. Based on the results of the financial assessment, a recommendation is given to the municipality.

The city of Rotterdam and its port have been constantly growing over the last decades. As the port is ensuring a place in the top ten ports in the world, the city of Rotterdam is changing as well, growing and becoming a more international town. The municipality of Rotterdam is planning to build a 3rd bridge that will cross the Nieuwe waterweg and will connect the eastern or western part of the city center to improve the economic growth, welfare and attainability of the city. Although the exact location of the bridge is still under investigation, the construction of the bridge will obstruct the passage of cruise ships and consequently, they will not be able to reach Kop van Zuid where the current cruise terminal is located.
Moreover, new buildings will be constructed in the coming years at Kop van Zuid. The construction of these buildings will lead to more logistics problems at the current terminal that will influence the viability of the entire area. Currently, the port of Rotterdam is facing an increase of entrance demand of cruise ships. The number of double mooring calls and the dimensions of the cruise ships are expected to grow in the coming years. The current cruise terminal cannot, without technical improvements, guarantee enough berthing space for two cruise ships at the same time.
For these reasons, in 2015 the Port of Rotterdam Authority started the project “Zeecruise lange termijn visie”. One of the conclusions of the “Zeecruise lange termijn visie” project in case that the Port of Rotterdam Authority and the municipality of Rotterdam decide to change the location of the cruise terminal, was that the most suitable location for the future cruise terminal is Pier 1 of the Merwehaven. The Merwehaven is composed of four piers that were constructed between 1923 and 1931 using caissons as quay walls.
Due to the age of the construction of the caissons and the requirements imposed by the new cruise terminal, a full feasibility study of the Merrwehaven had to be performed. The feasibility study is described in this report and mainly concerns the adaptation of the existing quay wall of Pier 1. The aim of this study was to maintain the existing caissons, avoiding the demolition of the structure and the need for constructing a completely new quay wall.
The approach used to achieve this objective follows the principles of the basic design cycle of Roozenburg and Eekels. Different design phases distinguish this method and the structure of this report follows these phases.
In the first phase, the functions, operational aspects, boundary conditions and assumptions of the Merwehaven and cruise market were analyzed. Based on this analysis the quay walls of Pier 1 were assessed. The main scope of the assessment was to establish whether the quay walls meet the requirements for the new cruise terminal and to identify the main issues that hinder the mooring of the cruise ships. The assessment proved that the quay walls do not meet the requirements of the new cruise terminal. Therefore, the conclusion was that to maintain the existing caissons of Pier 1 and ensure their stability a technical design solution must be provided.
Different design concepts were proposed to solve the issues that hinder the mooring of the cruise ships along the caissons. Through a first design loop, the design concepts that did not have sufficient feasibility to become the final solution were excluded. From the remaining design variants the best design variant was selected, by means of an evaluation based on a Multi Criteria Analysis (MCA) and a cost estimation. From this evaluation, it turned out that the best technical design solution is to drive an underwater sheet pile wall in front of the caissons of Pier 1.
Then, before performing the detailed design of the best design variant, special attention was given to the design bollard capacity of the cruise terminal. The bollard force is an important load in the design of quay walls. Hence, an extended study concerning the loads acting on the design cruise ship was carried out to define the required bollard capacity of the new cruise terminal. From this study, it turned out that the wind force is the dominant load acting on the design cruise ship and that the effect of passing vessels can be neglected. Based on this conclusion a static mooring analysis was performed to determine the load on the mooring lines of the design cruise ship and consequently the required bollard capacity. On the basis of the results of this analysis, the conclusion was that the existing bollards located on top of the caissons cannot withstand the mooring force and therefore new bollards with a capacity of 1700 kN have to be provided.
In the last phase, the design variant with underwater sheet pile wall was elaborated in more detail. This detailed design was performed by analyzing the overall stability of the caisson and the deformation of the underwater sheet pile wall using the PLAXIS software. Based on these analyses the conclusion was that the design variant with the underwater sheet pile wall can adapt the existing caisson, used as quay wall at Pier 1 in the Merwehaven for the future cruise terminal of Rotterdam.

The inland waterways are an important part of the freight transport system of the Netherlands. In the coming years, a lot of maintenance and construction works are needed to keep the network operational. This can temporarily impact the availability of the waterways section which can have negative effects on the performance of inland vessels and the waiting time for locks at alternative routes. In this research a method was developed that can be used to study these effects. In the method AIS data is used to analyze several aspects the inland waterways transport system. Additionally, a simulation model was developed in which the results of the AIS analysis are used to create an accurate representation of the system. The method was applied to case study to determine the applicability. It was concluded that the developed method can be applied when studying the effects of planned maintenance and construction works, but it is best used to estimate where the impacts are expected to be high
rather than to calculate exact results.

Uncertainties in the soil parameters play a major role in the design of quay walls. In the current design approach, partial factors are prescribed to account for uncertainties in the soil, as well as for other types of uncertainties. This semi-probabilistic (level I) design approach needs to result in a reliable design for a range of quay structures and for multiple soil stratifications. It is therefore expected that, in general, this method results in overdimensioning of the structure. Whether this assumption holds, is investigated in this thesis by carrying out a reliability analysis for two quay walls in the Port of Rotterdam. The first case study covers a simple double-anchored combi-wall, whereas in the second case study a quay wall with relieving platform is considered.
Only the most relevant failure mechanisms were considered, which are yielding of the combi-wall, yielding of the anchor bar, shear failure of the grout body and soil mechanical failure. These failure mechanisms are complex soil-structure interaction problems. Therefore, both the soil and the quay structure have been modelled with the finite element program Plaxis 2D, using the Hardening soil model. For performing the probabilistic calculations on this model, the probabilistic module ProbAna has been used. This is a package developed by Plaxis which couples several types of reliability methods to the finite element software of Plaxis 2D. As the computational effort is relatively large when using FEM, the First Order Reliability Method (FORM) was used over sampling methods like Directional Sampling and Crude Monte Carlo simulation.
The results for the simple quay wall showed that the reliability level was sufficient for all considered limit states. Hence, almost all partial factors derived on this quay wall were lower than currently prescribed by the Eurocode. In the second case study, a quay wall with relieving platform, monitoring data of multiple years was used for calibration of the Plaxis-model. Thereafter, the reliability for the limit states yielding of the wall and soil mechanical failure was evaluated. It turned out that for both limit states, the reliability index was too low compared to the target reliability.
Although each case study concerned a different type of quay wall, the results reveal that choices made in the design, either optimistic or pessimistic, can have large influence on the reliability. Perhaps just as important, are the assumptions made regarding the stochastic description of the soil. It is still under discussion up to what distance soil parameters are correlated in space and how spatial averaging should be applied. Reference calculations showed that choices regarding the amount of independent soil layers and the degree of spatial averaging have a large influence on the reliability. More fundamental research to these topics is therefore recommended.