A critical appraisal of the use of simple time-money trade-offs for appraisal value of travel time measures

Transportation - Stated choice surveys have established themselves as the preferred approach for value of travel time elicitation with the help of choice models. However, major differences exist in...     

Improving the coexistence of offshore wind farms and shipping: an international comparison of navigational risk assessment processes

The continued growth and evolution of the offshore wind industry, and the emergence of other novel marine uses such as wave and tidal generators, have upped the ante for spatial planners, as well as consenting and approval authorities in various coastal states. These stakeholders rely on processes such as navigational risk assessments (NRAs) to balance safety and efficiency requirements and to make optimal decisions over use of space. Given the increasingly complex and crowded seascape, however, there are some apprehensions about potential shortcomings in these NRA processes. There is also some concern that these inadequacies may lead to unsafe or inefficient marine spatial use. To understand how NRA processes can be improved further, a literature review is conducted, followed by a survey of respondents who are involved in the planning, consenting and/or approval of offshore wind farms across seven different countries. A summary of the NRA processes in these seven countries is presented, and several shortcomings are identified. Based on the findings of the survey, a list of recommendations is presented to enhance existing NRA processes—and to improve the coexistence of shipping and offshore wind farms (OWFs).     

A simulation-based probabilistic design method for arctic sea transport systems

When designing an arctic cargo ship, it is necessary to consider multiple stochastic factors. This paper evaluates the merits of a simulation-based probabilistic design method specifically developed to deal with this challenge. The outcome of the paper indicates that the incorporation of simulations and probabilistic design parameters into the design process enables more informed design decisions. For instance, it enables the assessment of the stochastic transport capacity of an arctic ship, as well as of its long-term ice exposure that can be used to determine an appropriate level of ice-strengthening. The outcome of the paper also indicates that significant gains in transport system cost-efficiency can be obtained by extending the boundaries of the design task beyond the individual vessel. In the case of industrial shipping, this allows for instance the consideration of port-based cargo storage facilities allowing for temporary shortages in transport capacity and thus a reduction in the required fleet size / ship capacity.     

Influence of wheel and rail profile shape on the initiation of rolling contact fatigue cracks at high axle loads

The influence of wheel and rail profile shape features on the initiation of rolling contact fatigue (RCF) cracks is evaluated based on the results of multi-body vehicle dynamics simulations. The damage index and surface fatigue index are used as two damage parameters to assess the influence of the different features. The damage parameters showed good agreement to one another and to in-field observations. The wheel and rail profile shape features showed a correlation to the predicted RCF damage. The RCF damage proved to be most sensitive to the position of hollow wear and thus bogie tracking. RCF initiation and crack growth can be reduced by eliminating unwanted shape features through maintenance and design and by improving bogie tracking.     

On the implementation of an auxiliary pantograph for speed increase on existing lines

The contact between pantograph and catenary at high speeds suffers from high dynamic contact force variation due to stiffness variations and wave propagation. To increase operational speed on an existing catenary system, especially for soft catenary systems, technical upgrading is usually necessary. Therefore, it is desirable to explore a more practical and cost-saving method to increase the operational speed. Based on a 3D pantograph–catenary finite element model, a parametric study on two-pantograph operation with short spacing distances at high speeds shows that, although the performance of the leading pantograph gets deteriorated, the trailing pantograph feels an improvement if pantographs are spaced at a proper distance. Then, two main positive effects, which can cause the improvement, are addressed. Based on a discussion on wear mechanisms, this paper suggests to use the leading pantograph as an auxiliary pantograph, which does not conduct any electric current, to minimise additional wear caused by the leading pantograph. To help implementation and achieve further improvement under this working condition, this paper investigates cases with optimised uplift force on the leading pantograph and with system parameter deviations. The results show that the two positive effects still remain even with some system parameter deviations. About 30% of speed increase should be possibly achieved still sustaining a good dynamic performance with help of the optimised uplift force.     

Virtually being there: Human aspects of shore-based ship assistance

Shore-based ship assistance is a topic that increasingly is attracting attention from the maritime community. Subjects such as shore-based pilotage and VTS are often discussed and there is technological and political pressure towards more extensive forms of such assistance. Perhaps less often mentioned, but not less important, is the human side of these subjects. The present paper examines two of the central concerns for the people who actually work within today’s VTS centers, namely communication and trust. The study consisted of a literature review, study visits, observations and interviews. Communication and trust are found to be closely related, and one main finding is that adapting one’s means of communication to the context can be a very powerful (and necessary) tool for the creation of trust. Another important result is that the ability of the shore-based operator to see the situation from the viewpoint of the crew is crucial for the creation and maintenance of trust.     

Modelling the investment decision of the entrepreneur in the tanker sector: choosing between a second-hand vessel and a newly built one

It is often the case that the investor in the shipping sector faces the dilemma of investing in a second-hand vessel or building a new one. This happens because an active second-hand market for almost all kinds of vessels exists. We argue that one of the prime considerations for the investment decision should not be the price of the vessel per se, second-hand (SH) or newly built (NP) but

• ?(a)?the relative price ratio (SH/NP) second-hand price over the new building price and

• ?(b)?the movement of this ratio.

We investigate the determinants of this ratio across different vessel sizes in the tanker sector and show that it can be used as an effective tool in investment decision as well as in asset appraisal.

We employ monthly data between 1995 and 2006 for four different ship sizes–VLCC, Suezmax, Aframax and Handysize–and implement an error correction model.

The investment decision depends on a number of risk and return variables as well as the perceived speed of adjustment of the price ratio to its equilibrium level.

Overall we claim that the cyclicality of the shipping sector together with expectations formed by the agents operating in it (the entrepreneur, the ship-owner and the broker), determine the movement of the ratio and hence the decision of the entrepreneur.     

What Curriculum for Mobility and Transport Studies? A Critical Exploration

To understand the complex meanings of mobility and to engage in transport planning and management processes, a variety of disciplines, skills, and tools are potentially useful. Universities have a limited amount of time and resources to train future professionals though. This poses a problem: where should the teaching priorities be? By means of a web-survey, this study has asked academics based at a number of universities what the disciplines, skills, and tools that — according to their personal viewpoints — are the most relevant for practitioners in the mobility and transport sector. The respondents generally support curricula that facilitate a holistic, non-specialised, understanding of mobility and transport issues.     

The Impact of Urban Freight Transport: A Definition of Sustainability from an Actor's Perspective

Abstract

This paper presents a definition of sustainable urban freight transport (SUFT), based on the existing theories and concepts, and develops an indicator set that describes SUFT. The definition of SUFT makes a categorisation of actions possible which enables actors to select effective strategies towards SUFT. The indicator set consists of two levels: impact indicators – which describe how the urban freight transport violates the principles of sustainability; and performance indicators – which describe different categories determining the characteristics and performance of the urban transport system. A literature study analyses the characteristics determining the performance of actors in the urban freight transport chain. Knowing the current state and improvement potential of the urban freight transport system are prerequisites for defining successful strategies and implementing effective actions.