· · · Institutional Repository

Abstract not available

New railways? Extra roads? Pricing policies to reduce environmental harmful transport emissions? Politicians face tough choices. What are the costs of these proposals? Will the plan result in the expected impacts? What are the risks of a plan? Who wins, who loses? This thesis is about the Dutch practice of helping public decision-making by answering these kinds of questions. Four cases of policy-related ex ante evaluations are evaluated. Ex ante evaluation refers to forward-looking assessment of the likely future effects of new policies of proposals. The four cases in this thesis show the importance of being clear about choices, assumptions and uncertainties. Without clarity, ex ante evaluations will become unused "black boxes", or they may lead to wrong policy decisions. The cases show a different approach of dealing with future uncertainty. The Dutch government has stated the importance of testing policies and investment plans in different possible futures. Testing evaluates the future robustness of the impacts of a plan, giving policy-makers insight into the uncertainty related to ex ante estimates, instead of giving a false feeling of certainty as may have happened in two of the four cases, in which only one future was used.

Motivated by the desire to explore future traffic flows that will consist of a mixture of classical vehicles and vehicles equipped with advanced driver assistance systems, new mathematical theories and models are developed. The basis for this theory was borrowed from the kinetic description of gas flows, where we replaced the behaviour of the molecules by typical human driving behaviour. From a methodological point of view, this 'human-kinetic' traffic flow theory provides two major improvements with respect to existing theory. Firstly, the model builds exclusively on a mathematical description of individual driver behaviour, whereas traditionally field measurements of traffic flow variables like flow rate and average speed of the flow are needed. This is of major importance for the exploration of future traffic flows with vehicles and equipment that are not yet on the market, and for which at best individual test results from driving simulator experiments or small scale field trials are available. Secondly, the model accounts for the more refined aspects of individual driver behaviour by considering the 'internal' state of the driver (active/passive, aware/unaware,...) and the variations of driving strategy that occur during driving. This is important when the ambition is to capture refined congestion patterns like the occurrence of stop-and-go waves, oscillating congestion and long jams, where the driving strategy may depend for instance on the motivation of the driver to follow closely. This new theory links together the worlds of traffic engineers and behavioural scientists. As such, it is a promising tool that increases the insight in the human behaviour as a basis of various dynamic congestion patterns, and it facilitates the design and evaluation of electronic systems in the vehicle that assist the driver to behave safer, more comfortable and more efficient in busy traffic flows. Herewith, the results of this research are relevant, both for the theoretical interest of the TRAIL research school, and for the more practically oriented work of TNO, who provided financing for this research in the joint T3 research program.

The thesis deals with the design and implementation of a distributed framework for real-time traffic management using microscopic online simulation.

Traffic controllers monitor railway traffic sequencing train movements and setting routes with the aim of ensuring smooth train behaviour and limiting as much as existing delays. Due to the strict time limit available for computing a new timetable during operations, which so far is rather infeasible by using existing tools, railway traffic controllers usually restrict themselves mostly to a few manual timetable modifications and the chosen traffic control actions may be often sub-optimal. This PhD thesis is principally concerned with the design, implementation and evaluation of an advanced and robust laboratory tool for supporting railway traffic controllers in the everyday task of managing timetable disturbances. This dynamic traffic control system co-ordinates the speed of successive trains on open track, solves expected route conflicts and provides dynamic use of platform tracks in stations or alternative paths in a corridor between stations. Blocking time theory for modeling track occupation and signaling constraints is combined with alternative graphs for solving dynamic traffic control problems with the aim of increasing the punctuality and the use of infrastructure capacity at a network scale. The feasibility of the dispatching options is verified in a very short computation time by dynamic updating of the corresponding headways, train speeds and blocking time graphs, while the costs of the alternative dispatching options are measured in terms of maximum and average delays between consecutive trains at stations and other relevant points within the investigated network. To this end, the following achievements are included: (i) An innovative model for railway traffic optimization is presented to predict accurately train traffic flows and to enable the computation of optimal network schedules, i.e., all trains are managed simultaneously in a railway network for a given time period. (ii) The development of fast and effective scheduling algorithms based on the proposed model for the real-time management of a complex railway network is addressed. The objectives are to predict the evolution of train traffic within short computation times and to improve the punctuality by pro-actively detecting and solving train conflicts. (iii) A better use of rail capacity and a further improvement of punctuality are achieved by an iterative adjustment of train orders and routes in case of disturbances. Novel problem dedicated algorithms highlight the potential use of rerouting instead of only rescheduling the trains in order to limit the delay propagation as much as possible. (iv) Constructive algorithms for the dynamic modification of running times are provided that satisfy the timetable constraints of train orders and routes and guarantee the real-time feasibility of the running times, while respecting the signaling and safety systems in use. (v) A temporal decomposition method is introduced for the short-term traffic planning and control over a time period of up to several hours. This approach is of interest for traffic controllers since delays between running trains propagate considerably in time and space during heavily perturbed operations. (vi) A large set of computational studies on real-world instances proves that the automated decision support tool provides better solutions in terms of delay minimization compared to dispatching rules adopted by traffic controllers. Test beds are the hourly timetables of the Schiphol railway bottleneck and of the Utrecht - Den Bosch dispatching area. We study practical size instances and different types of disturbances, including multiple delayed trains, dwell time perturbations and blockage of some tracks.

In Transport Sciences different implementations of Utility Theory are commonly used for the description and prediction of human choice behaviour. Almost 30 years ago Kahneman and Tversky proposed an alternative behavioural-economic model of choice behaviour called Prospect Theory. In contrast to Utility Theory they assumed that preference orders depend on the choice context. The most important differences between Extended Prospect Theory and Utility Theory are: preferences for one alternative over another are not stable but may change with the circumstances; people frame alternatives as changes compared to a reference state; they adapt that reference state almost immediately once a choice is made; and they attach a much higher value to a loss of, for example, ten minutes leisure time compared to an increase of the same size. This book demonstrates that in many occasions an Extended Prospect Theory explains the choice behaviour of people better than Utility Theory for the whole range of travel choice contexts. It also proposes a mathematical model based on Extended Prospect Theory that, compared to a similar Utility Theory-model, appeared to offer a better prediction of the responses of car owners in Singapore to the introduction and changes in the road pricing fares from 1975 to 2005.

Worldwide belt conveyors are used to transport a great variety of bulk solid materials. The desire to carry higher tonnages over longer distances and more diverse routes, while keeping exploitation costs as low as possible, has fuelled many technological advances. An interesting development in the recent past is the distribution of drive power along the path of a belt conveyor, which has resulted in the multiple driven belt conveyor. The main idea behind this study is based on finding the right balance between the locally applied drive power and the occurring resistances in such a multiple driven belt conveyor system, so the belt tension stays within the safety margins in a controlled manner. Existing sub models describing belt dynamics, mechanical resistances and the transfer of drive force onto the belt are investigated, and expanded if necessary, so they can be combined to create a complete model of a distributed driven belt conveyor. The combined model serves as a base to test existing design rules used for conventional single drive belt conveyors and to investigate what modifications are required in the multiple drive case.

This thesis presents new tools and methods for the design and validation of advanced driver assistance systems (ADASs). ADASs aim to improve driving comfort and traffic safety by assisting the driver in recognizing and reacting to potentially dangerous traffic situations. A major challenge in designing these systems is to guarantee high performance and dependability under all possible combinations of traffic scenarios, operating conditions, and failure modes. These stringent requirements necessitate fault-tolerant control techniques and a thorough validation of the system. A microscopic traffic simulation within the simulation environment PreScan supports the initial system design. In addition, a unique tool for the design and validation of ADASs is presented and evaluated: vehicle hardware-in-the-loop (VeHIL) simulation. The VeHIL laboratory allows an ADAS-equipped vehicle to be tested in an artificial environment, where surrounding traffic is emulated by robot vehicles. VeHIL enables repeatable, safe, and accurate testing, complementary to human-in-the-loop test drives. The use of these three tools (PreScan, VeHIL, and test drives) is combined in a methodology for probabilistic validation of ADASs, based on randomized algorithms. This methodology is more efficient than conventional simulation techniques and the current practice of trial-and-error test drives. It results in a test schedule definition with a minimum number of simulations and test runs, such that the performance and dependability of an ADAS can be guaranteed, given a desired level of accuracy and confidence. The added value of the methodology is demonstrated with three case studies, involving a driver information and warning system, a fault-tolerant system for cooperative adaptive cruise control, and a pre-crash system.

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.

Abstract not available

Abstract not available

Cities have changed. People have changed. The 21st century, western citizens of the world travel more often, with more comfort, and longer distances than ever. History shows that a growing economy leads to a growing human need for communication and mobility. The daily action space of people exceeds by far the borders of their own city or village. The Network City is a reality. The essence of the (practical) field of urban design and planning concerns the making of plans in behalf of the vitality of urban areas. The vitality of todayââ¬â¢s city is endangered most (reasoned from the perspective of mobility) by: 1 the (direct, but especially indirect) space consumption of infrastructures and vehicles; 2 the decrease of accessibility of urban areas; 3 the absence of coherence between the hierarchical levels in the urban network. It is widely agreed among urban experts that the new urban technologies, among others transport technologies, play a major role in (the development and transformation of) todayââ¬â¢s socio-spatial environment. But it is still quite unclear how these new technologies should be interpreted in terms of the planning and design of the Network City. The main objective of this research is to generate those kinds of guidelines and recommendations for the planning and design of the Network City, all from a mobility point of view. In general terms, this thesis focuses on the mutual relation between city functioning and transport systems. More specifically, it focuses on the case studies of collective demand-responsive transport, and the location choice (process) of transfer points.

This thesis presents a framework for the control of automated guided vehicles (AGVs). The framework implements the transport system as a community of cooperating agents. Besides the architecture and elements of the framework a wide range of infrastructure scene templates is described. These scene templates, ranging from terminal infrastructure to freeways, can be used as building blocks to create a control system for an automated transport network.

The subject of this thesis is the application of dynamic road pricing in dynamic networks.Both forms of dynamics represent the outstanding elements of this dissertation. Its objective is the formulation and testing of a design methodology for an optimized tolling system for road networks.

In this thesis, transport infrastructure slot allocation has been studied, focusing on selection slot allocation, i.e. on longer-term slot allocation decisions determining the traffic patterns served by infrastructure bottlenecks, rather than timetable-related slot allocation problems. The allocation of infrastructure capacity among carriers is a major issue in various transport infrastructure sectors, and therefore a theoretical framework on slot allocation would be desirable to support rational decision-making on slot allocation. The current state-of-the-art of slot allocation research does not provide such a theoretical framework, and therefore a theoretical framework to analyze slot allocation problems has been developed in this thesis. The first step in the development of a theoretical framework to analyze slot allocation problems has been the specification of a conceptual framework, which includes the definition of key concepts such as capacity. Capacity has been defined as being dependent on conditions such as composition of traffic and traffic context as well as assumptions about the desired balance between capacity and quality-of-service. The next step was to review the current application of slot allocation in the railway and aviation sectors, and the potential application of slot allocation in the road and navigation sectors. Slot allocation is currently applied in the railway and aviation sectors, and slot allocation may potentially be applied in other sectors. This thesis introduces the important distinction between selection and scheduling slot allocation. In both the railway and aviation sectors, the tradition has been to integrate selection and scheduling slot allocation. This thesis, however, considers selection slot allocation as a separate slot allocation level. Separating selection and scheduling slot allocation enables the application to each level of different rules with respect to slot validity, valuation of alternative slot requests, etc. The desired characteristics of selection slot allocation have been formulated in this thesis by analyzing the main desires of carriers and other interested parties such as shippers and authorities. It has been concluded that selection slots should be valid for a significantly longer period than scheduling slots, and a semi-static slot allocation procedure has been proposed. Furthermore, the acceptability principle has been introduced as a basis to specify desired slot size. However, the specification of standard basic slots by the allocation body (at different levels to attain differentiation of slot size) is desirable. A semi-static slot allocation procedure implies that selection slot allocation decisions may be based on an explicit evaluation of selection slot requests. The selection problem may be analyzed using congestion theory, resulting in a generic specification of traffic supply and demand. The next step is to specify traffic supply in more detail by specifying capacity constraints. Examining various types of primary traffic processes, traffic service processes, and traffic externalities, capacity constraints have been formulated, which may be applied to different types of bottlenecks. Three categories of capacity constraints have been distinguished, i.e. homogeneous capacity constraints, linear capacity constraints, and non-linear capacity constraints. The next step is the specification of objectives. The (primary) objective of slot allocation may usually be specified as a linear objective function. Depending on the type and number of capacity constraints, various instances of selection slot allocation decision problems may be formulated. The corresponding optimization problems may be solved using an exact solution algorithm, but for various reasons this thesis proposes a greedy approximation instead. Besides a standard greedy algorithm for selection problems with a single type of capacity constraint, an extended greedy algorithm has been developed to solve problems with two or more different types of capacity constraints. The latter algorithm has been tested for a hypothetical case study. Three main conclusions have been formulated in this thesis. The first main conclusion is that selection and scheduling should be considered as separate slot allocation levels having a hierarchical relationship. Selection slot allocation is of primary importance and scheduling slot allocation is only of secondary importance, because selection decisions determine which traffic is facilitated and which is not. The second main conclusion is that the validity of slots is a compromise between stability and flexibility. To ensure a sufficient level of stability, a validity of at least 5 years seems reasonable for selection slots. To ensure a reasonable level of flexibility, infinite validity of selection slots (historic rights) is not desirable, and at least every timetable season the opportunity should be offered to reserve selection slots. The final main conclusion is that the objec-tives and constraints of the selection problem can be modeled as linear functions, and the resulting binary linear programming problem can best be solved with the greedy efficiency algorithm presented in this thesis. This efficiency algorithm does not provide an exact solution of the binary linear programming problem, but its results are more robust and are easier to interpret than exact solution approaches.

In The Netherlands, dynamic traffic management is an important approach to minimise the negative effects of increasing congestion. Measures such as ramp metering and route infor-mation, but also conventional traffic signal control, are used for this. Traditionally, the focus in designing traffic control plans has been on local control. There is however a tendency to come to a more centralised way of traffic control. For a centralised approach the interaction with route choice behaviour and other traffic management measures becomes an important aspect in the design of control strategies. The research described in the thesis shows that integrated anticipatory control can contribute to a better use of the infrastructure in relation with policy objectives. Integrated control means that the network is considered to be one multi-level network, consisting of motorways and urban roads. Anticipatory control means taking into account not only the current, but also fu-ture traffic conditions in relation with route choice behaviour. A framework was developed, which can be used to design and evaluate traffic management strategies. With the use of the framework it was shown for some simple networks that anticipatory control leads to less de-lay, also if more than one road authority is involved. The framework can be used as a next step towards real network traffic management.

Given the high number of encounters in traffic and the low number of accidents in which these result, it can be concluded that road users are quite good at interacting safely. To achieve a better understanding of this interactive behaviour, this thesis focused on road users' expectancies. In an explorative study, the aspects road users mention in their expectancies of interaction situations in traffic were studied. The mentioned aspects were distinguished into three categories: references to 1) right of way, 2) other road users and 3) the location of other road users (past, present and future). Subsequently, two experiments were conducted using linked driving simulators, which allowed for the study of interaction behaviour between two real people, rather than between a real and a pre-programmed road user. In the experiments, participants were confronted with expected and unexpected behaviour of a road user coming from an intersecting road. Additionally. in the second experiment, the interaction space was increased (by adjusting the infrastructure and providing information). The results showed that participants tended to take right of way when they were entitled to it, but also when they were confronted with another road user slowing down. Unexpected behaviour does not necessarily lead to a critically unsafe situation. The available interaction space is initially used to safely settle the interaction situation; additional interaction space is used to increase efficiency. It can be concluded that car drivers are quite capable of dealing with situations in which the behaviour of other car drivers is in conflict with the priority regulation if the interaction space allows for it.

At the start of the 21st century overtaking on two-lane rural roads is a major traffic safety problem. However, this dissertation research demonstrates that most drivers are perfectly able to safely perform these manoeuvres. Their time spent in the left lane is about eight seconds. Preparing subtasks of the manoeuvre, such as checking surrounding vehicles' behaviours, changing gear and starting accelerations are started in the right lane. In this way, available overtaking gap in the oncoming traffic stream are optimally used. This anticipative behaviour is accounted for in the proposed overtaking assistant design, which informs the driver about overtaking gaps three seconds before they become available. This system is developed to assist less daring drivers with overtaking and to prevent risk-taking drivers to perform overtaking manoeuvres in unsafe situations. A driving simulator experiment demonstrated that this assistant does not much affect overtaking efficiency, drivers' comfort or safety, as long as the threshold for a safe gap is chosen such that the safety margin with the first oncoming vehicle remains above three seconds. A microscopic traffic simulation study shows that when this threshold is eleven seconds, traffic system efficiency remains similar or increases slightly due to increased number of overtaking manoeuvres. Drivers' safety during overtaking increases, because the time-to-collision with oncoming vehicles will not become smaller than three seconds. And, drivers' comfort is improved in terms of higher overtaking frequencies and less time spent following. To introduce the proposed overtaking assistant to the market, vehicle-to-vehicle communication is necessary. This technology enables vehicles to localise all other surrounding vehicles. The automotive industry works hard on the development of vehicle-to-vehicle communication, however, it will take at least another ten years before the first overtaking assistant as proposed in this dissertation, will become available.