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201.
This paper synthesizes evidence from the workshop on risk and reward in public transport contracting. It broadens the usual risk/reward framework to encompass strategic/tactical level issues, identifying high level community goals as the ultimate risk/reward pay-off. The evolution of tactical level public transport planning is reviewed, noting considerable change in functional roles between purchaser and provider in some jurisdictions. No single “best” approach is evident but an emerging interest in relational contracting founded on trust is apparent. Risk allocation between purchaser and provider is considered, a key debate concerning the extent to which providers should be exposed to revenue risk. 相似文献
202.
Juan de Dios Ortúzar Gonzalo Rodríguez 《Transportation Research Part D: Transport and Environment》2002,7(6):2519
A stated preference ranking experiment is designed to estimate the willingness-to-pay (WTP) for reducing the amount of atmospheric pollution in a group-based residential location context. Important issues are the proper definition of the context and the variable metric for the environmental attribute. Sample members were asked to rank 10 options arising from variations in the attributes travel time to work and to study, rent of the house and an environmental attribute (the number of days of Alert, in terms of concentration of PM10, at a dwelling’s location). Multinomial logit models based on a consistent microeconomic framework were estimated for various stratifications of the data (income, pollution sensitivity, and type of dwelling currently inhabited). From these subjective values of time and WTP were derived for reductions in the number of days of alert and hence the amount of pollutant concentration at a given location. The WTP came out at about 1% of the family income for reducing one contingence day per year; this is approximately 60% higher than an estimate reported for the city of Edmonton, Canada, but the average PM10 concentration in Santiago is about six times higher. 相似文献
203.
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205.
Manivannan Kandasamy Seng Keat Ooi Pablo Carrica Frederick Stern Emilio F. Campana Daniele Peri Philip Osborne Jessica Cote Neil Macdonald Nic de Waal 《Journal of Marine Science and Technology》2011,16(2):157-167
This paper details the CFD validation studies carried out as a prerequisite for multi-fidelity CFD-based design optimization
of high-speed passenger-only ferries aimed at reducing far-field wake energy that causes beach erosion. A potential flow program
(WARP) and a URANS program (CFDSHIP) were validated using full-scale measurements of resistance, sinkage, trim, and far-field
wake train obtained over a wide range of speeds for two high-speed semi-planing foil-assisted catamarans: Spirit (LOA-22 m)
and 1060 (LOA-17 m). This study posed a unique combination of challenges for CFD modeling: the foil appended geometry required
complicated surface overset grids, the effect of the waterjet and wind resistance had to be modeled, and a method had to be
devised to extrapolate the calculated near-field elevation to get the far-field wake train using Havelock sources. A more
concentrated effort was applied to the URANS verification and validation which forms the focus of this paper. The results
show that URANS is able to accurately predict the resistance and motions for both vessels when coupled with models that account
for the propulsors and air resistance. The overall accuracy of URANS for the performance analysis of the foil-assisted, semi-planing
catamarans was adequate to warrant its use as a tool for subsequent design and optimization of a new vessel with significantly
reduced wakes. 相似文献
206.
207.
Spurred by the expanding bulk shipping and technological innovations, dry bulk vessels have gained considerable development in ship types, ship design, and operation since the invention of the first specialized dry bulk carrier in the early 1950s. However, questions like: what changes in technical specifications have occurred for dry bulk vessels during the past four decades; what triggered these changes and what impacts have these specific changes had on shipping costs or earnings potential, have never been examined systematically in previous work. Subsequently, this article attempts to investigate changes in main technical specifications and relationships between the main technical variables and their economic performance measured by costs and revenues of dry bulk carriers. Technical changes in speed, deadweight, lightweight, and engines are checked for the main types of dry bulk vessels, and trends revealed in these developments are demonstrated to be the consequences of both technical improvement and economical considerations. Additionally, it has been found that the earnings potential differs much from dry bulk vessels with different technical specifications. This can be manifested in the sensitivity analysis. The analysis of this article may contain useful information to practitioners of dry bulk shipping in guiding their market decisions about ship building and operations. 相似文献
208.
Abstract In recent years, concern has grown over good practices in the procurement process in public–private partnerships (PPPs). The consensus view is that PPPs are prone to higher transaction costs than traditional public provision. In this paper, we contrast the hypothesis that transaction costs in transport PPPs depend, to a large extent, on the procurement mechanism used in each case, comparing the Negotiated and the Open procedures. Given that PPPs may offer considerable benefits and significant savings over the entire life cycle of the project, it is essential for PPPs to minimize those costs that undermine efficiency gains and that deter private involvement. The quantitative analysis undertaken in this paper highlights that there is room for important savings in the tendering of PPP transport infrastructure projects, using an Open procedure. 相似文献
209.
AbstractTo date, most empirical studies have applied cross-sectional designs to investigate the relationship between the built environment (BE) and travel behaviour (TB). Since these studies cannot identify causal influence, the use of designs that provide data on multiple moments in time seems necessary. This article classifies these designs and describes how they can be applied to identify causality in this relationship. We recommend the use of natural experiments to assess the impact of changes in land use/infrastructure and prospective longitudinal designs to assess the impact of residential or job moves. In addition, the role of the BE can be explored by assessing the impact of (1) deliberate TB change experiments and (2) changes in household circumstances across different spatial contexts over time. The use of randomised experimental designs is recommended for the former and prospective longitudinal designs for the latter. The article concludes with an outlook on future research. 相似文献
210.
AbstractThe ongoing process of port reform has led to an increasing number of publicly owned but corporatised port authorities (PAs). The performance effects of corporatisation have been analysed, for example, for the airports industry, often showing positive effects. This paper reviews the literature on port reform and the relationship between port governance structures and performance. It also presents a first case study on the effects of corporatisation of PAs, namely for the Port of Rotterdam Authority, a publicly owned but corporatised port development company. In 2004, this organisation was transformed from a municipal department to an independently operating company. The performance indicators to evaluate the effect of this corporatisation include market share, turnover, operating costs, profits, and investments. These indicators are evaluated for two periods, one prior to the corporatisation (1997–2003) and the other afterwards (2005–11). The comparison of these two periods shows that corporatisation has led to significant improvements of all performance indicators. The findings derived from this case study are relevant for the ongoing discussion on port governance models. 相似文献