Modeling travel time reliability of freeways using risk assessment techniques

Travel time reliability is considered to be one of the key indicators for the performance of transport systems and is measured in various ways. This paper synthesizes both reliability concepts: traffic breakdown, the indicator of the instability of travel times, is treated as the risk, whereas travel time variability, the indicator of the uncertainty of travel times, is considered as the consequence of this risk. An analytical formula, using risk assessment technique, explicitly expresses the cost of travel time unreliability as the sum of the products of the consequences (i.e. variability) and the corresponding probabilities of breakdown. It provides a novel measure of travel time reliability and is applicable in network performance evaluations. An empirical example based on a large dataset of freeway traffic flow data from loop detectors shows that the developed travel time reliability measure is both intuitively logical and consistent.     

ERTMS安全性研究——第三篇 ERTMS/ERTML

ERTMS/ERTML是欧洲铁路运输系统管理层的缩写(European Rail Traffic Management Sys-tem/European Rail Traffic Management Layer).ERTML的目标是建立一个高层次的全欧洲铁路运输管理系统.到目前为止,影响其运作决策的主要因素是双边协议及合同.     

A global view on port state control: econometric analysis of the differences across port state control regimes

This article is based on 183 819 port state control inspections from various port state control regimes for the time frame 1999 to 2004. Using binary logistic regression, we establish the differences of port state control inspections across several regimes, even though theory predicts there should be no significant differences in treatments of vessels. The results indicate that the differences towards the probability of detention are merely reflected by the differences in port states and the treatment of deficiencies and not necessarily by age, size, flag, class or owner as perceived by the industry and regulators. The analysis further shows that some differences can be found across ship types and regimes and that there appears to be room for further harmonization in the area of port state control.     

Coming Soon to a Fjord Near You: Future Jellyfish Scenarios in a Changing Climate

Over the last decades, a dense population of the deep-sea/oceanic scyphozoan jellyfish Periphylla periphylla has established itself as top predator in the Trondheimsfjord in Norway, which has caused the traditional fisheries in this fjord to suffer. This was, however, not the first fjord this jellyfish invaded, and data suggest that it will not be the last one, either. With warmer temperatures, the jellyfish is moving northward in Norway, but not all fjords are created equal, and it is not thriving or taking up residence just anywhere. The current article explores three fjords in which Periphylla periphylla has become the top predator and outcompeted former ones. The main question of interest is why the jellyfish becomes dominant in one fjord and not another. The next question is which other Norwegian fjords further north exist with similar characteristics where we therefore would expect Periphylla periphylla to proliferate in the future. The latter is important from a policy and adaptation perspective for the local community of people, since the proliferation of the species unmistakably leads to fewer fish for commercial harvest and potentially less attractive waters for tourism purposes. Results show that three northern fjords, the Skjerstadfjorden the Holandsfjorden, and Stordjupna in the Vestfjord appear to be particularly vulnerable to a future Periphylla periphylla invasion.     

Decision-making for light rail

In transport literature there is an ongoing discussion on the potential of light rail in mitigating congestion and supporting mobility around urban centres. Throughout Europe and the United States, many policy makers see light rail as an interesting option to improve the accessibility of urban centres. The Dutch national government wanted to support swift light rail realization in a number of promising situations.Several projects gained support from the national government for implementation. However, the decision-making on a local level was not nearly as swift as expected and not in line with the promise. This paper presents an analysis of that perceived slowdown and shows that the approach of the national government with a strict focus on light rail and a detachment from the local processes has played an important role in the slowdown. It shows that light rail can very well be a solid option. However, its successful implementation is not solely dependent on light rail suitability for the mobility patterns in the region, but very much on the approach of the implementation of those supporting the option.     

Can passenger flow distribution be estimated solely based on network properties in public transport systems?

Transportation - We present a pioneering investigation into the relation between passenger flow distribution and network properties in public transport systems. The methodology is designed in a...     

Reconstructions of marine environmental conditions and scenarios for future changes

Long-term changes of environmental conditions are fundamentally important for many sectors in the maritime industry. Observational evidence from which such long-term changes may be reliably derived is often limited. Here we briefly illustrate the present situation and present an approach on how quasirealistic environmental models can be used in combination with existing data to reconstruct recent long-term changes and to derive scenarios of future developments. We concentrate on variables of primary importance for the maritime industry, namely wind-storms, wind-waves and storm surges. Examples are provided for the North Sea area.