Operational route choice methodologies for practical applications

This paper focuses on the application of tractable route choice models and presents a set of methods for deriving relevant disaggregate and aggregate route choice indicators, namely link and route flows. Tractability is achieved at the disaggregate level by the recursive logit model and at the aggregate level by the mental representation item (\(\mathrm {MRI}\)) approach. These two approaches are analyzed here, and extensions of the \({\mathrm {MRI}}\) approach are presented. The analysis elaborates on the features of each model and allows to draw insights into the use of a specific model, depending on the needs of the application and the data availability. The performance of the two models is tested on real data. The results demonstrate the validity of the \({\mathrm {MRI}}\) model that is intended for aggregate analysis.

     

Governance for Sustainability: Insights from Marine Resource Use in a Tropical Setting in the Western Indian Ocean

The last decade has seen a shift in the Natural Resource Management discourse, a shift from management to governance. Governance is held forward as a prime solution to problems associated with the sustainability of natural resources, including fisheries and other marine resources. Several countries in the Western Indian Ocean are framing governance solutions as a response to coastal/marine resource depletion and environmental degradation, but the challenges are huge and success stories remain few. This study provides an analysis of the governance situation in Chwaka Bay, Zanzibar, Tanzania. It presents the governance actors and how governance is expressed in terms of hierarchy (state), heterarchy (self-organized networks of resource users), and anarchy (market). The analysis illustrates the extreme difficulties of using governance approaches to steer human behavior to solve environmental problems and achieve sustainability. The study also provides some insights when considering the use of governance as a tool for the “designing” and/or “steering” social–ecological systems in subsistence contexts with weak formal institutions. These include the consideration of governance as an intrinsic part of complex societal processes, the idealization of governance as a template for redressing management failure and broader issues such as the importance of meta-governance.     

Traffic accident risk perception among drivers: a latent variable approach

ABSTRACT

Governments require decision tools to deal with road traffic accidents, a pandemic resulting in millions of deaths around the world. Evidence shows that human factors are one of the major causes of road accidents, and there is much interest in identifying variables that may have an impact on drivers’ perception of risk. To this aim, we design a stated choice experiment with eight hypothetical driving scenarios considering attributes that have been strongly associated with increased accident risks: (i) driving speed, (ii) driving the wrong way in a one-way street, (iii) overtaking on a bend, and (iv) driving under the influence of alcohol or drugs. Data from a sample of survey respondents are used to estimate a hybrid discrete choice model incorporating two latent variables, Driver Concentration and Safe Driving. Our results may contribute to the design of public policies geared to prevent accidents by encouraging safer driving behaviour.     

Addressing endogeneity in strategic urban mode choice models

Transportation - Endogeneity is a potential anomaly in econometric models, which may cause inconsistent parameter estimates. Transport models are prone to this problem and applications that...     

Multi-fidelity optimization of a high-speed foil-assisted semi-planing catamaran for low wake

The wakes of high-speed passenger-only ferries that operated through Rich Passage, on the Seattle-Bremerton ferry route, caused beach erosion and damage to habitat. A task was initiated to design a low-wake high-speed vessel using multi-fidelity CFD based design optimization by using low-fidelity potential flow solvers for initial global design optimization and by using URANS solvers for high-fidelity tuning of the optimized design. This simulation based design process involved a close collaboration between ship designers, and hydrodynamics and CFD specialists, whose collective expertise guided the evolution of the design based on both hydrodynamic and structural aspects. The initial hull shape optimization using potential flow code was carried out by blending three different initial concepts provided by the designers. Subsequently, URANS was used to evaluate the potential flow optimized hull and to further optimize the hull configuration parameters, namely, the centre-of-gravity, demihull spacing, foil location, foil angle and slenderness ratio at different displacement conditions. The URANS based configuration optimization also took into account the far field wakes’ energy spectrum with an objective of reducing the energetic, low frequency far field wakes which are associated with beach flattening on the mixed sand and gravel beaches. Calculation of the far field wake using URANS would require an unfeasibly large domain size; therefore, a Havelock code with a source distribution matching the URANS calculated near field wave elevation was used to propagate the wakes into the far field. The end result of the optimization was a design with significantly reduced far field wake, which is currently being built for experimental testing.     

Traffic congestion pricing methodologies and technologies

This paper reviews the methods and technologies for congestion pricing of roads. Congestion tolls can be implemented at scales ranging from individual lanes on single links to national road networks. Tolls can be differentiated by time of day, road type and vehicle characteristics, and even set in real time according to current traffic conditions. Conventional toll booths have largely given way to electronic toll collection technologies. The main technology categories are roadside-only systems employing digital photography, tag & beacon systems that use short-range microwave technology, and in-vehicle-only systems based on either satellite or cellular network communications. The best technology choice depends on the application. The rate at which congestion pricing is implemented, and its ultimate scope, will depend on what technology is used and on what other functions and services it can perform.     

Global ship risk profiles: Safety and the marine environment

This article uses visualization techniques to investigate global ship risk profiles and their changes over time. With a unique data set of 49,151 observations, the authors link changes in risk profiles to legislative developments and industry actions, as well as identify areas prone to general safety, loss of life, and pollution risks. Improved risk profiles over time have resulted from legislative measures, including the International Safety Management Code, the Oil Pollution Act, amendments to the International Convention for the Prevention of Pollution from Ships, and the introduction of port state controls and industry vetting inspections.     

谈施工安全控制

分析了常见施工安全事故的特征及事故发生的原因，并结合多年的施工经验，介绍如何控制和保障施工安全的经验和体会。     

A model for allocating car parking spaces in universities

In this paper a linear programming model has been presented for determining the optimum allocation of existing car parking facilities for different classes of users within a closed community, of which a university is a typical example.     

车用稀燃增压单一燃料CNG发动机电控系统的研究

为深入研究 CNG发动机稀薄燃烧特性 ,进一步降低天然气发动机的有害排放 ,设计了车用增压天然气发动机电控系统。该系统采用高能点火模块来获得天然气着火所需的点火能量 ,电控喷射单元采用模糊控制器来获得比较精确的空燃比控制 ,实现对天然气发动机的顺序多点喷射。运用该系统对增压单一燃料 CNG发动机的燃烧和排放性能进行了试验研究 ,结果表明了该系统的有效性。