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Network robustness is the ability of a road network functioning properly facing unpredictable and exceptional incidents. A systematical framework with combined dynamic traffic assignment (DTA) models is designed for the analysis of road network robustness. With this framework, network performance considering travelers' (route) choice behavior under both normal traffic condition and incident condition can be properly described. So the robustness of road networks against incidents can be analyzed comprehensively. Based on such knowledge, road networks robustness can be improved from the planning stage or with suitable measures.

Transport networks in major urban areas are becoming more and more vulnerable to unforeseen disturbances in transport networks, like incidents. For the near future, we expect an increasing number of incidents with a large impact due to the overall increase of the traffic load. In this paper the hypothesis is tested that, if no measures are taken, the impact of incidents increases in the future and, therefore, the vulnerability of the road network increases. It is shown that the current network of the area The Hague-Rotterdam in the Netherlands is already vulnerable. If the demand increases, the increase in total travel time is more than linear with the increase in demand in the situation without an incident. The impact of incidents also increases when the level of demand increases. This results in the overall conclusion that it is necessary to make the road network more robust.

The Dutch road network is, like many other road networks in the world, congested in the morning and evening peaks. The locations of congestion are quite often the same; this makes it relatively easy to take the delay of this regular congestion into account when planning a trip. However, as a result of disturbances, also unexpectedly large delays occur. If no measures are taken, the Dutch road network, especially in major urban areas, is becoming more and more vulnerable to disturbances like incidents. This PhD study proposes a framework for robustness analysis that includes definitions, indicators and a set of measures that can be applied to make the road network robust against incidents. Furthermore, a method is developed by which robust road networks can be designed given these measures. The method combines expert knowledge with advanced modelling techniques. The quality of the method is proven by applying it to a small test network. Finally, this thesis shows how the method can be applied to a large realistic network of Amsterdam and surroundings. The practical value of the research appears from the fact that parts of it have already been used in projects for the ANWB, Verkeer en Waterstaat, de Raad voor Verkeer en Waterstaat, DVS, de stadregio Amsterdam en Bart Egeter Advies. This research is supported by the TU Delft, TNO, NGI, Transumo and TRAIL.

There is a growing awareness that road networks, especially in major urban areas, are becoming more and more vulnerable to unforeseen disturbances like incidents because of the fact that the level of congestion keeps growing. Therefore, robustness measures have to be taken. In this paper the robust road network design problem is presented as well as a solution algorithm for solving the problem. The solution algorithm combines expert knowledge with advanced modeling techniques. In this way the method can be applied to large scale networks. This paper shows the quality of the algorithm for a test network.

The Dutch national road network has been developed over several decades. In the past, roads were constructed according to the then current spatial and transportation planning philosophies. Because the existing road network is a result of a long process of successive developments, the question can be asked whether this network is the most appropriate from the current point of view, especially taking in consideration the current socio-economic structure of the Netherlands. To answer this question an optimization algorithm for designing road networks has been developed. With this algorithm the Dutch road network has been redesigned based on minimization of the travel and infrastructure costs and by taking into account the socio-economic structure of the Netherlands. A comparison between the existing network and the new design shows that the redesigned Dutch national road network has significantly lower total costs than the existing road network. It is found that the construction of less roads with more lanes on different locations leads to a reduction of the total travel time and the total vehicles kilometers traveled.