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Markine V.L.,Technical University of Delft | Shevtsov I.Y.,ProRail
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit

The article describes a numerical procedure for optimum design of a railway wheel profile. The optimization performed using the optimality criteria based on a rolling radius difference function, which account for the reduction ofwear and contact stresses aswell as for stability of the vehicle. As a general optimization technique the multipoint approximations method is employed. The described procedure has been applied to improve the wheel profile design for a passenger train that was suffering from rolling contact fatigue defects in the rails and wheels. In order to account for uncertainties inherent to the wheel production process, the robustness of the optimum wheel profile was analysed. The failure criterion was formulated using the vehicle stability requirement. The failure probability was estimated using the Monte Carlo method and modified Latin hypercube sampling technique. The results are presented and discussed. © Authors 2011. Source

Plantinga H.E.C.,ProRail | Doree A.G.,University of Twente
Proceedings 30th Annual Association of Researchers in Construction Management Conference, ARCOM 2014

In public procurement, most contractors view the qualifying procedures they are obliged to follow as time consuming and wasteful. For one category of public clients, EU rules offer an alternative to qualifying for each project. Public clients operating in the water, energy, transport or telecommunications sectors may establish and operate a so-called 'qualification system'. This offers contractors the opportunity to qualify for a period of time rather than an individual project. The reasons for applying such a qualification system seem traditionally to be rooted in reducing transaction costs, particularly where the administrative demands are significant relative to the typical value of contracts. As such, it may seem self-evident that a client's choice between the two approaches should be based on cost efficiency considerations. However, cost efficiency may not be the only motive behind employing a qualification system. A case study is presented here that examines the evolution of such a system and the corresponding reasoning by its operator. While exploring the usability of a conceptual model for managing procurement knowledge, additional reasons for operating the qualification system are reconstructed by exposing the implicit organizational knowledge. Initial results show that formal reasons are combined with implicit ones. These implicit reasons are found to be key in explaining the current utilization of the qualification system. Over time, implicit reasons get included in the reasoning process and come to dominate the original formal reasons. Without proper explication of these reasons, the real value of the qualification system may remain undetected. The contributions of this paper are twofold. First, it reports a case study in which the usability of a model developed for managing procurement knowledge is explored. Second, this paper offers a first insight into the evolution of a qualification system and the corresponding reasoning by its operator. Source

Plantinga H.E.C.,ProRail | Doree A.G.,University of Twente
Proceedings 29th Annual Association of Researchers in Construction Management Conference, ARCOM 2013

For fifteen years, the Dutch railway agency (ProRail) has implemented various alliance elements in its procurement strategies. Several project alliancing applications have been developed and applied in succession, ranging from a limited shared risk domain to a directly tendered full alliance model. The progress seems to be evolutionary rather than planned. The emergence of these alliance variants suggests implicit motivations and expectations. Changing the implicit reasoning to explicit logic could help in the evaluation and development of alliance approaches, from project-based evolutionary adaptations to a conscious planned strategy. This study considers a number of alliance projects. The variation amongst these projects is mapped against a number of criteria derived from the literature. Contracting plans, the tendering board's minutes, contracts and other policy documents were scanned and interviews were held with key players to reconstruct the motivations for the various alliance approaches. The initial results confirm that changes and choices made in terms of the particular alliance domain are mostly implicit and only sparsely explained by motivations. This paper will present a first overview of ProRail's alliancing variants, corresponding motivations and expectations, plus more explicit insights into the prevailing implicit reasoning. This study offers a first step in mapping the variation in alliance methods, evaluating their effects and moving the implicit evolutionary development of alliance methods towards more deliberate planned choices in future alliancing variations. The next step in the research project will be to verify the validity of the expectations and logic regarding alliancing. Source

Wan C.,Technical University of Delft | Markine V.,Technical University of Delft | Shevtsov I.,ProRail
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit

Rail pads and under sleeper pads (USPs) are resilient elements inserted between the rail and the sleeper, and between the sleeper and the ballast, respectively. They improve the elastic properties of the track's superstructure. In this paper, the approach of estimating the performance of a turnout by using the dynamic forces acting on the crossing as indicators of the extent of crossing nose damage is improved by tuning the stiffness and damping of the rail pads and USPs using a numerical optimisation method. In the optimisation problem, the dynamic forces acting on rails, sleepers and the ballast bed, which should be minimised, are considered in the objective function. Constraints are imposed on the displacements of the structural elements of the turnout crossing. The combined multi-objective optimisation problem is solved using the multipoint approximation method. The results of the optimisation show that application of softer rail pads combined with USPs can significantly reduce the dynamic forces acting on the rails, sleepers and ballast. Moreover, the track elasticity should be varied along the crossing. © IMechE 2014. Source

Pel A.J.,Technical University of Delft | Bel N.H.,ProRail | Pieters M.,Significance
Transportation Research Part A: Policy and Practice

Transit passengers' response to crowded conditions has been studied empirically, yet is limitedly included in transport models currently used in the design of policy and infrastructure investments. This has consequences for the practical applicability of these models in studies on, for instance, timetabling, train capacity management strategies, project appraisal, and passenger satisfaction. Here we propose four methods to include the effect of crowding, based on existing studies on passengers' perception and response as well as often-used crowding indicators. These four alternative methods are implemented in the train passenger assignment procedure of the Dutch national transport model, and evaluated with respect to their impacts on the model results for the Dutch railway network. The four methods relate to four different ways in which an additive trip penalty and/or time-multiplier can be incorporated in the train utility function for different travel purposes, to capture the disutility of crowding as measured by the load factor. The analyses of the test case favor the hybrid method using both a boarding penalty (capturing seat availability upon boarding) and a time-multiplier (capturing physical comfort and safety throughout the trip). This method produces consistent results, while the additional computational effort that it imposes is acceptable. Further empirical underpinning is needed to conclusively show which of these methods best captures passengers' response behavior quantitatively (for different travel purposes and conditions). © 2014 Elsevier Ltd. Source

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