Effectiveness of travel time reliability indicators in the light of the assessment of dynamic managed lane strategy

ABSTRACT

The aim of traffic management is to ensure a high quality of service for a maximum number of users by decreasing congestion and increasing safety. Uncertainty of travel times decreases the quality of service and leads end users to modify their plans regardless of the average travel time. Indicators describing travel time reliability are being developed and should be used in the future both for the optimization and for the assessment of active traffic management operations. This article discusses the efficiency of certain reliability indicators in an ex-post assessment of a traffic management strategy. Ex-post assessment is based on an observational before–after study. As some factors other than the studied management strategy may intervene between the two periods, and as most reliability indicators require knowledge of the full travel time distribution and not only its average, a methodology is developed for the identification of the impact of these exogenous factors on the whole distribution. Many reliability indicators are split into different parts allowing the identification of the part due to the management strategy impact. The methodology is tested numerically on a managed lane operation consisting of Hard Shoulder Running (HSR) at rush hour on a section of a French motorway. The variation of some reliability indicators appears misleading, whereas the splitting of the indicators increases our understanding of the strategy and highlights its impact. The paper gives the reliability assessment of the HSR field test and discusses different reliability indicators to identify their potential performances and shortcomings.     

Experimental study on a model azimuthing podded propulsor in ice

The objective of this study was to investigate the performance of a model azimuthing podded propulsor in ice-covered water. Model tests were carried out with two different depths of cut into the ice (15 and 35 mm), two different ice conditions (presawn and pack ice conditions), and four different azimuthing angles. The depth of cut is the maximum penetration depth of the propeller blade into the ice block. The 0.3-m-diameter model propeller was operated in a continuous ice milling condition. Ice loads were measured by several sensors which were installed in various positions on the model. Six one-axis pancake-style load cells on the top of the model measured the global loads and two six-component dynamometers were installed on the shaft to measure the shaft loads. One six-component dynamometer was attached to the one of the propeller blades inside the hub to measure the blade loads. The pod unit and propeller performance in ice are presented. Ice-related loads, which were obtained when the blade was inside the ice block, are introduced and discussed. During the propeller–ice interaction, a blade can experience the path generated by the previous blade, which is called the shadowing effect. The effects of shadowing, depth of cut, azimuthing angle, and advance coefficient on propulsor performance are presented and discussed.     

A dynamic CSTT model for the effects of added nutrients in Loch Creran, a shallow fjord

Despite a tendency for the complexity of physical–biological models to increase, simple coupled models remain useful for some applications and can provide insights into crucial links between physical and biological processes. This argument is illustrated with an account of a simple 3-box model intended to help assess the capacity of fjords to assimilate nutrients from fish farms. The model, a dynamic version of the UK “Comprehensive Studies Task Team” (CSTT) steady-state model for eutrophication, was applied to Loch Creran (Scottish Western Highlands) and was implemented using Stella 8 and tested using historical data from 1975 (before the installation of a salmon farm) and field data collected in 2003, during the period of operation of the farm. The model's biological state variables are chlorophyll, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), and it includes a simple run-off model to convert rainfall into river discharge. The physical processes involved in exchange between the loch and the adjacent waters of the Firth of Lorne were parameterised as a constant daily exchange rate.Between 1975 and 2003, local inputs of nutrient increased but, despite this, there was little apparent increase in nutrient concentrations in the loch, and observed chlorophyll concentrations decreased substantially. Model simulations of chlorophyll and DIN agreed well with observations in 1975, as did DIN simulations in 2003. However, simulated chlorophyll was overestimated in 2003.Some of the agreement between observations and simulations come from the use of observed boundary conditions to force the model. However, even when boundary conditions are subtracted from simulations and observations, the simulations in most cases retain a significant correlation with observations, demonstrating that the model's ‘interior’ processes do add to its ability to replicate conditions in the loch.     

隧道防水技术

除了抽水和堵漏外,还有更多的地下水控制措施.即使是需要采取这些措施,但地下水破坏情况的调查过程可能漫长且要花费人力、物力.最佳的办法是及早考虑潜在的问题,因此有必要正确进行现场调查.     

A spatial equilibrium port cargo projection model

A mathematical spatial programming model developed to analyse changes in international and hinterland commodity flows through a regional port system is applied to wheat shipments through the U.S. Pacific Northwest port system. Two scenarios, one focusing on a Chinese quarantine on wheat shipments from the Pacific Northwest and the other on possible closure of barge transportation on the Columbia-Snake River, illustrate the capacity of the model to evaluate the impacts of international and hinterland shocks on the regional port system.     

Attitudes toward Participation in Cooperative Coastal Management: Four European Case Studies

Findings are reported of the VALCOAST project that had as one of its research objectives to ascertain: (a) stakeholder willingness to participate and cooperate in coastal management (CM), given local and national CM practices; and (b) stakeholder assessment of the "accessibility" and "friendliness" of current CM processes. The project involved case studies and stakeholder interviews in Belgium, Greece, Spain, and the UK. Major findings include: (1) most stakeholders are willing to cooperate in three out of the four case areas, but not to the same extent; (2) the participating "officials" in the case studies are expecting the stakeholders to be less willing to cooperate than the latter indicate; (3) stakeholders in all case studies do not expect to be heard by those responsible for CM, find it difficult to learn about the relevant institutional arrangements, and consider the communication of the objectives and anticipated impacts of CM policies to be inadequate. It is concluded that the strong evidence of stakeholders' potential willingness to cooperate in local initiatives is very encouraging for a devolved, regional approach to European Union coastal management policies, provided that this potential is capitalized upon in such policy processes.     

Empowering professional women in the Maritime World: the WMU contribution

Promoting the increased participation of women in the economic fabric of developing countries is a fundamental goal of the United Nations. The International Maritime Organization (IMO) and the World Maritime University (WMU) are working to bring about a sustained change in gender imbalance in the maritime sector, to bring the skills and expertise of women to bear on a vital global industry. This report details WMU’s strategies to date, the conference held by WMU in April 2008, Empowering Professional Women in the Maritime World, and the Conference Declaration and Resolution supported by members of the IMO Technical Cooperation at its 58^th session in June 2008.     

Coordination of last train transfers using automated fare collection (AFC) system data

This paper studies last train coordination problem for metro networks, aiming to maximize the total number of passengers who can reach their destinations by metro prior to the end of operation. The concept of last boarding time is defined as the latest time that passengers can board the last trains and reach final destinations. The corresponding method for calculating last boarding time is also put forward. With automatic fare collection system data, an optimization model for coordinating last trains is proposed. The objective function optimizes the number of passengers who can reach their final destinations during the train period using departure times and headways of last trains for each line as decision variables. Afterwards, an adaptive genetic algorithm is put forward to solve this model and is applied to a case study of the Shanghai metro system. Copyright © 2017 John Wiley & Sons, Ltd.     

Community Severance: Where Is It Found and at What Cost?

Community severance occurs when transport infrastructure or motorised traffic divides space and people. Despite the growing awareness of its effects on the wellbeing of local communities, the problem is not usually assessed quantitatively or assigned a monetary value. This paper reviews existing practice and research on quantitative methods dealing with community severance. The problem is first decomposed into a series of questions, which are then used as a base to review the methods found in governmental guidance documents, technical reports, and academic studies. The paper ends with recommendations for the integration of severance issues into transport planning.     

Spatial and Temporal Modeling of Beach Use: A Case Study of East Anglia,UK

As tourists are sensitive to weather conditions and changes to the environments they visit, it is likely that climate change will affect coastal recreation in the future. To understand these impacts, it is first important to quantify how visitor numbers are associated with beach characteristics and weather patterns. Using the East Anglian coastline, UK, as a case study, information on the spatial distribution of visitors recorded from aircraft flights is combined with beach characteristic data in a Geographical Information System. In addition, surveys are undertaken at two beaches to assess temporal variations in visitation. The study finds a diverse range of characteristics are associated with visitor numbers. These findings are evaluated alongside the anticipated effects of climate change and management policies. Although it is predicted that warmer weather will increase visitor numbers overall, sea-level rise may reduce numbers at wide sandy beaches, which are currently most preferred by tourists.