Optimization of emergency crossovers and signals for emergency operations in rail rapid transit

This paper presents a methodology for designing rail transit systems to meet operating requirements when track maintenance or failure cause sections of tracks to be unavailable for service. The methodology can be also used to establish the requirements for the continuity of operations during construction. The main objective of the paper is to develop a tool which performs trade-offs between system costs and level of services during emergencies/construction. Several alternatives, including various signal and control systems, number and types of crossovers and corresponding operating strategies, are developed and evaluated against capital investments. Operating measures and strategies for the selected alternative can be recommended before the design phase is completed, because the designer, by using this methodology, is aware of the capacities attained during emergencies and construction.     

Productivity of first-generation container terminals: Sydney, Australia

In 1969 the first of Sydney's purpose-built container facilities in Port Jackson, the Seatainer terminal, became operational. Later, in 1973, the second terminal at Glebe Island, a common-user facility, shared the task of handling the container traffic for much of eastern Australia until the development of the new facilities in Botany Bay. The two terminals differed in almost every respect except their inner-city locations and restricted sites. This paper explores these differences and their implications for terminal productivity. It examines some of the structural characteristics of the container trade and traffic and defines vessel time profiles and container handling rates for operations over the sample years 1977, 1979 and 1981. The paper establishes that there were remarkably similar productivity characteristics at the two terminals, despite their significant characteristics, but it also reveals the relatively high proportion of vessel alongside time or time spent at the berth that was idle, non-working or unproductive.     

Containerization in ports of Third-World Asia: an overview of present patterns and the direction of future growth

Although containerization in Third World Asian ports may not conform to the 'usual' model of containerization in developed countries the region represents a significant generator of container tonnage. Moreover, despite considerable intra-regional differences in throughput productivities, some of the ports are achieving efficiencies and productivities markedly higher than those in well established ports in Western countries. The region has been characterized, too, by strong patterns of mainline/feeder interdependencies. This paper reviews the status of containerization in Third World Asia and suggests that major changes, reflecting a variety of factors, are likely by 1990.     

Swimming for survival: A role of phytoplankton motility in a stratified turbulent environment

We investigate a role for vertical migration in stratified coastal water, where the swimming speed is generally significantly less than the typical turbulent fluctuations in a tidally-mixed bottom layer. In our modelling approach we use a k- turbulence model to describe the physical forcing, a Lagrangian random walk model to describe the vertical displacement of individual cells in response to turbulence and due to cell motility, and a phytoplankton growth model to direct the swimming behaviour of the phytoplankton according to their light and nutrient requirements. The model results show how the cells form a stable subsurface chlorophyll maximum (SCM) at the base of the thermocline where episodic tidal turbulence causes erosion of part of the SCM biomass into the bottom mixed layer (BML). We then focus on the question of whether an ability to swim (weakly, compared to typical bottom layer turbulent intensities) provides any advantage by allowing return to the SCM. Our results show that tidal turbulence in the BML helps both motile and neutrally-buoyant cells by periodically pushing them into the base of the thermocline. Motile cells then have the advantage that they can swim further into the thermocline towards higher light which also reduces the likelihood of being re-mixed back into the BML.     

Explaining obesity with urban form: a cautionary tale

In recent years, there has been a dramatic increase in studies exploring associations between the built environment and obesity. Many studies have found that built environment characteristics, such as high-density land developments, mixed-land uses, and connected street networks, are associated with lower rates of obesity. However, depending on the research field and the researcher, how one specifies the experimental model and how sociodemographic characteristics of the population are defined and included in the model has led to different policy conclusions and implications. This is not a surprising observation; however, it is one that does seem to have been lost in current discussions. This article highlights several data-processing, model-specification, and model-estimation factors that should be comprehensively considered in studies of the built environment and obesity. Empirical results based on data from Atlanta, GA, USA, illustrate that the association between the built environment and obesity is sensitive to how age, income, and educational attainment are included in the model. Also, a detailed examination of land-use-mix measures shows that it is difficult to create this measure and that results are sensitive to the treatment of missing values. Models that distinguish between overweight and obese individuals are shown to provide richer insights into the associations among obesity, built environment, and sociodemographic characteristics for the Atlanta area. The article concludes by offering modeling recommendations for future studies.

Fatigue in transport: a review of exposure,risks, checks and controls*

Human fatigue continues to threaten safe transport. There are claims that employers of operators should do more to mitigate the risks, and several regulators are promoting fatigue-risk management in the context of safety management systems (SMS). The current paper reviews fatigue-related risk and exposure factors and control measures for operators of land- and sea-based transport forms. Our review identifies 13 types of measures for the monitoring or control of fatigue risks: optimal staffing; optimal schedule design; optimisation of breaks/naps; monitoring of actual hours worked; optimisation of work content; monitoring and feedback of actual sleep; health screening and treatment; promotion of recovery from work; fitness-for-duty testing; monitoring of fatigue symptoms while operating; control of fatigue while operating; performance monitoring and assistance; and fatigue-proofing. We also identify two systemic measures needed to anchor risk mitigation in SMS: organisational learning and training/other. By structuring monitoring and control measures along Dawson and McCulloch’s [Managing fatigue: It’s about sleep. Sleep Medicine Reviews, 9(5), 365–380] fatigue-risk trajectory, a framework is obtained that acts as a guide for fatigue-risk management by transport employers. To inform transport managers further, evaluations are needed of the effectiveness of individual control measures as well as whole fatigue-risk management interventions.     

The safety ladder: developing an evidence-based safety management strategy for small road transport companies

Traffic accidents account for between 20% and 40% of work-related accidents in industrial countries, and research indicates that road transport companies often have little focus on organisational safety management (OSM). There is thus a huge and largely untapped road safety potential in improving the safety of people who drive in their work, by focusing on OSM. Road transport companies in European countries are often small, however, with limited resources in terms of time, financial resources and competence on road safety. The main aim of the present article is therefore to develop an OSM strategy for small road transport companies. Based on a systematic literature review, taking Norwegian research as its point of departure, the article concludes that four measures seem to be most realistic for small goods-transport businesses, and that these measures seem to have the greatest safety potential. These four measures can be arranged on a ladder, where businesses start at the lowest and most basic level, before proceeding to the next step. While our stepwise safety-ladder approach has not been validated, it is expected that further research would confirm the value of the strategy proposed.     

A two-dimensional framework for the understanding of transportation planning models

This article puts forward the view that, for each transportation planning or management problem, there is a particular way to simultaneously define the multiple levels of procedures useful for the problem and set it in its proper perspective, the latter essentially by the identification of what is exogenous and endogenous to the problem at hand. The joint determination of these levels and of the exogenous/endogenous mix defines the two-dimensional frame of each problem. To develop our view, we extend our previous conceptual framework to include, in the first dimension, an activity location procedure, and to distinguish, in the second dimension, between operational, tactical, and strategic perspectives. We conclude by relativising the use of solution techniques by making them ancillary to the situation planning requirements.     

DRAG-ALZ-1, a first model of monthly total road demand,accident frequency,severity and victims by category,and of mean speed on highways,Algeria 1970–2007

We construct a first country-wide model of demand for road use and of road safety outcomes for Algeria making use of the DRAG-type framework and of flexible regression estimation methods that make a demonstrable difference to the quality of our results. We imply that the availability of high quality Algerian data could make it worthwhile not only to consider updates of the model with longer data series but also to study variants of the model, notably with disaggregation of freight activities across industrial sectors.     

Boundaries of the coastal zone: A survey of state laws

Abstract

A survey of coastal state legislation reveals several types of statutes affecting activities occurring in coastal regions: Coastal management statutes, wetland statutes, and shoreline statutes. Each coastal state has adopted methods to delineate coastal areas or features, whether an entire coastal zone, a limited feature such as wetlands, or shorelands. Boundary delineation is done according to linear measurements, political boundaries, roads and highways, vegetation, elevation, tidal flow, and other factors. An appendix is provided containing state statutory provisions relating to boundary‐delineation techniques.