Estimating the marginal cost of railway track renewals using corner solution models

Economic theory advocates marginal cost pricing for efficient utilisation of transport infrastructure. A growing body of literature has emerged on the issue of rail marginal infrastructure wear and tear costs, but the majority of the work is focused on costs for infrastructure maintenance. Railway track renewals are a substantial part of an infrastructure manager’s budget, but in disaggregated statistical analyses they cause problems for traditional regression models since there is a piling up of values of the dependent variable at zero. Previous econometric work has sought to circumvent the problem by aggregation in some way. In this paper we instead apply corner solution models to disaggregate (track-section) data, including the zero observations. We derive track renewal cost elasticities with respect to traffic volumes and in turn marginal renewal costs using Swedish railway renewal data over the period 1999–2009. This paper is the first attempt in the literature to apply corner solution models, and in particular the two-part model, to disaggregate renewal cost data in railways. It is also the first paper that we are aware of to report usage elasticities specifically for renewal costs and therefore adds important new evidence to the previous literature where there is a paucity of studies on renewals and considerable uncertainty over the effects of rail traffic on renewal costs. In the Swedish context, we find that the inclusion of marginal track renewal costs in the track access pricing regime, which currently only reflects marginal maintenance costs, would add substantially to the existing track access charge. EU legislation requires that access charges reflect the ‘costs directly incurred as a result of operating the train service’, which should include a marginal renewal cost component. This change would also increase the cost recovery ratio of the Swedish infrastructure manager, thus meeting a policy objective of the national government.     

An algorithm for combining autonomous vehicles and controlled events in driving simulator experiments

Autonomous vehicles can be used to create realistic simulations of surrounding vehicles in driving simulators. However, the use of autonomous vehicles makes it difficult to ensure reproducibility between subjects. In this paper, an effort is made to solve the problem by combining autonomous vehicles and controlled events. A controlled event can be compared to a theatre play. The aim is to achieve the same initial play conditions for each subject, which can be problematic since the traffic situation around the subject will be dependent upon each subject’s actions while driving in autonomous traffic. This paper presents an algorithm that achieves the transition from autonomous traffic to a predefined start condition for a play. The algorithm has been tested in the Swedish National Road and Transport Research Institute (VTI) driving simulator III with promising results. In most of the cases we examined the algorithm could reconstruct the specified start condition and conduct the transition from autonomous to controlled mode in a inconspicuous way. Some problems were observed regarding moving unwanted vehicles away from the closest area around the simulator vehicle, and this part of the algorithm has to be enhanced. The experiment also showed that the subjects drove faster in the presence of controlled everyday life traffic normally used in the VTI driving simulator than in autonomous traffic.     

An alternative to FASTSIM for tangential solution of the wheel–rail contact

In most rail vehicle dynamics simulation packages, tangential solution of the wheel–rail contact is gained by means of Kalker's FASTSIM algorithm. While 5–25% error is expected for creep force estimation, the errors of shear stress distribution, needed for wheel–rail damage analysis, may rise above 30% due to the parabolic traction bound. Therefore, a novel algorithm named FaStrip is proposed as an alternative to FASTSIM. It is based on the strip theory which extends the two-dimensional rolling contact solution to three-dimensional contacts. To form FaStrip, the original strip theory is amended to obtain accurate estimations for any contact ellipse size and it is combined by a numerical algorithm to handle spin. The comparison between the two algorithms shows that using FaStrip improves the accuracy of the estimated shear stress distribution and the creep force estimation in all studied cases. In combined lateral creepage and spin cases, for instance, the error in force estimation reduces from 18% to less than 2%. The estimation of the slip velocities in the slip zone, needed for wear analysis, is also studied. Since FaStrip is as fast as FASTSIM, it can be an alternative for tangential solution of the wheel–rail contact in simulation packages.     

Road pricing and parking policy

The starting point of this paper is that the collection costs of urban road pricing have turned out to be unexpectedly high. A comparative cost analysis of the congestion charging system of London, Stockholm, Oslo and Singapore also shows that there are large collection cost differences. The most striking difference is between Oslo and London. Oslo, like Stockholm has the necessary, natural, qualities for a central city toll ring with a limited number of entrances; just 18 and 19 tollgates are required. For large historic cities like London with hundreds of inlets to the central city, tollgates at every entrance would involve high investment costs and be very obtrusive in the street scene. The problem is, however, that the present London charging system, with no tollgates, shows high running costs, ten times higher than in Oslo, in spite of the fact that the charged number of vehicles is the same in the two cities. This is a formidable obstacle to alleviating urban traffic congestion in many big cities.The charging technology could hopefully be developed, however, another approach is to develop and combine other measures including traffic regulation, parking policy and public transport subsidisation, which would be only second-best in a hypothetical situation where road pricing is without costs. This paper focuses on parking policy. Two strands of parking policy reform are discussed; fringe benefit taxation of free workplace parking which has recently been introduced in Sweden and a two-part tariff at parking meters, which is suggested as an extension of congestion charging to all day traffic within the central city.     

A Non-Linear Rubber Spring Model for Rail Vehicle Dynamics Analysis

A non-linear, dynamic rubber spring model is proposed. It mainly aims at representing the mechanical behaviour of rubber suspension components in rail vehicle dynamics. The model is one-dimensional, has five parameters and is based on a superposition of elastic, friction and viscous forces. The model is implemented in the computer packages MATLAB and GENSYS. Comparisons between model and measurement results for harmonic excitations show good agreement. A procedure to determine the model parameters from only two measured force-displacement loops is described. The model represents a reasonable compromise between accuracy and computational effort and should be a suitable tool in rail vehicle dynamics analysis.     

Workshop report - Public policy and transport

This workshop considered the wider public policy goals of a range of transport interventions. Particular attention was paid to assessing the role of integration of the different components of the transport system and of the integration of transport with other economic sectors. This assessment was informed by Ray Pawson’s realist evaluation approach, with its emphasis on the inter-relationships between context, process and outcome. The context was provided by case studies covering small urban areas, large urban areas and inter-urban corridors. The three key processes identified related to a regulated system with public ownership and control, a deregulated system with private sector ownership (‘competition in the market’) and a system in which there was public planning of the transport system but private provision (‘competition for the market’). Outcomes can be assessed using cost-benefit analysis tools to determine impacts on economic welfare or more qualitative approaches can be used to determine the extent to which accessibility or sustainability goals have been achieved. The evidence provided suggests that wider public policy goals are more important for urban than for inter-urban transport and it thus in urban areas where integration should be pursued with most vigour. The most relevant process for achieving this would seem to be variants of the competition for the market model. Some policy recommendations are made and implications for further research and for future conferences assessed.     

Quality incentives and quality outcomes in procured public transport - Case study Stockholm

Gross contracts appear to be the most common contract form for procured public transport in Sweden and elsewhere. This contract form, it has been argued, gives weak incentives for operators to deliver the desired quality level. Therefore many procuring public transport authorities amend contracts with quality incentives.This paper examines how such quality incentives influence quality outcomes with focus on cancelled departures and delays. The main findings are that the introduction of quality incentives are correlated with both increases and decreases of measured quality outcomes.We hypothesise that the results are driven by underlying cost changes for achieving desired quality objectives that exceed the possible revenues from the incentives. In interviews with the Stockholm public transport authority (SL) and some operators, two central observations surface. The first is that there are causes for quality failures that are not solely the responsibility of operators and that these are therefore not fully reached by the incentives, and the second is that the operators believe that they have exhausted what they can do under the current contracts.