Does the accessibility measure influence the results of residential location choice modelling?

Transportation - Accessibility is essential in land-use transport interaction frameworks. For residential location choices in particular, it has always been important at the theoretical level. At...     

Classification of Livebus arrivals user behavior

With the increasing use of Intelligent Transport Systems, large amounts of data are created. Innovative information services are introduced and new forms of data are available, which could be used to understand the behavior of travelers and the dynamics of people flows. This work analyzes the requests for real-time arrivals of bus routes at stops in London made by travelers using Transport for London's LiveBus Arrivals system. The available dataset consists of about one million requests for real-time arrivals for each of the 28 days under observation. These data are analyzed for different purposes. LiveBus Arrivals users are classified based on a set of features and using K-Means, Expectation Maximization, Logistic regression, One-level decision tree, Decision Tree, Random Forest, and Support Vector Machine (SVM) by Sequential Minimal Optimization (SMO). The results of the study indicate that the LiveBus Arrivals requests can be classified into six main behaviors. It was found that the classification-based approaches produce better results than the clustering-based ones. The most accurate results were obtained with the SVM-SMO methodology (Precision of 97%). Furthermore, the behavior within the six classes of users is analyzed to better understand how users take advantage of the LiveBus Arrivals service. It was found that the 37% of users can be classified as interchange users. This classification could form the basis of a more personalized LiveBus Arrivals application in future, which could support management and planning by revealing how public transport and related services are actually used or update information on commuters.     

Improving the estimation of total and direction-based heavy-duty vehicle annual average daily traffic

Abstract

The estimation of annual average daily traffic (AADT) is an important parameter collected and maintained by all US departments of transportation. There have been many past research studies that have focused on ways to improve the estimation of AADT. This paper builds upon previous research and compares eight methods, both traditional and cluster-based methodologies, for aggregating monthly adjustment factors for heavy-duty vehicles (US Department of Transportation Federal Highway Administration (FHWA) vehicle classes 4–13). In addition to the direct comparison between the methodologies, the results from the analysis of variance show at the 95% confidence level that the four cluster-based methods produce statistically lower variance and coefficient of variation over the more traditional approaches. In addition to these findings – which are consistent with previous total volume studies – further analysis is performed to compare total heavy-duty monthly adjustment factors, both directions of traffic, with direction-based monthly adjustment factors. The final results show that the variance as well as the coefficient of variation improve on average by 25% when directional aggregate monthly adjustment factors are used instead of total direction.     

Second-order sum-frequency wave diffraction by a truncated surface-piercing cylinder in bichromatic waves

This work considers the second-order sum-frequency diffraction problem for a stationary truncated surface-piercing circular cylinder in bichromatic waves. The solution method was based on a semianalytical formulation of the second-order sum-frequency diffraction potential. The boundary conditions were properly satisfied by introducing the “locked” and the “free” wave components of the nonlinear velocity potential. The method was validated by comparing the calculated results with numerical data previously reported by other authors. Particular attention was paid to the second-order sum-frequency heave forces and the change in the wave run-up configuration due to the existence of the lower fluid domain underneath the truncated cylinder.     

Cultural diversity, manning strategies and management practices in Greek shipping

The present paper examines the way Greek shipping companies and Greek seafarers perceive culture, and how this affects their approach to crew management and operation of the ships. The analysis focuses on the manning strategies employed by the companies, on the operational problems that might occur on-board, and on any possible disturbance of the relation between the ship, the office at shore and third parties. Finally, a number of management practices which, when implemented, help to overcome these problems is also examined. The research methodology includes a review of the existing literature and interviews conducted by means of questionnaires filled in by crew managers and seafarers. Results show that some of the predominant problems encountered aboard, as far as communication with multicultural crews is concerned, are rooted in cultural and linguistic incompatibility, as well as in inadequate and inappropriate training. Furthermore, crew managers and seafarers lack both a clear perception of culture, and share opinions on the implementation of manning strategies. The present paper concludes that culture management can enhance crew team cohesion, upgrade communication at all levels, and, finally, improve the quality of the working environment, the safety of the workplace and the overall performance of the team.     

Selective replacement of national by non-national seafarers in OECD countries and the employment function in the maritime sector

Commonly, in the shipping industry of the developed Organisation for Economic Cooperation and Development (OECD) countries, national seafarers are progressively being replaced by non-national ones. The present paper aims to provide a model for this tendency. Our analysis is based on the assumption that when shipowners are called to make decisions concerning crew characteristics (such as crew composition and employment levels), they address themselves to two distinct seafarer markets: the domestic (seafarers from OECD countries, henceforth to be referred to as ‘national’) and the non-national (seafarers from other countries). Whilst workers of the first market are better examples in the field of ‘on-the-job-performance’ (in terms of efficiency and loyalty) than workers of the second, shipowners set their domestic employment rule with the view to maximize their profits facing wages and ‘on-the-job-performance’ from national and non-national seafarers alike. Thus, national seafarers are chiefly recruited as officers and the employment level of non-national seafarers are residual, formed thereafter. Our findings point out that the employment rule concerning nationals is negatively affected by the former's wages, and positively by the wage increases of non-national seafarers and by eventual increases of the differential between the ‘on the job performance’ of nationals and that of non-national seafarers of corresponding specialisation.     

Safety in Greek coastal shipping: The role and risk of human factor revisited

The comprehensive analysis presented in this paper investigates the links and comparative assets between human factor and other factors that are important determinants of maritime transport risk. In this outline, the identification of factors, such as age and ship size, that can be statistically linked (i.e. statistical significance) to whether an accident in a passenger vessel can be attributed to human factor or other causes is addressed accordingly. This way, the role of human factor in relation to safety of Greek coastal shipping is revealed and the spotlight is able to focus on the various aspects and points that manifest the importance of human element in the maritime industry. The risk assessment of the transportation with Greek passenger ships is being used in order for the safety level of Greek coastal shipping to be adequately estimated. Moreover, the comparison between the values of risk for accidents caused by human factor and those attributed to other causes is an established way to bring to the fore the unbroken relationship between the human factor and marine accidents’ consequences. The paper is concluded with interesting insights and comments drafted through the aforementioned tasks.     

Exploiting the fundamental diagram of urban networks for feedback-based gating

Traffic signal control for urban road networks has been an area of intensive research efforts for several decades, and various algorithms and tools have been developed and implemented to increase the network traffic flow efficiency. Despite the continuous advances in the field of traffic control under saturated conditions, novel and promising developments of simple concepts in this area remains a significant objective, because some proposed approaches that are based on various meta-heuristic optimization algorithms can hardly be used in a real-time environment. To address this problem, the recently developed notion of network fundamental diagram for urban networks is exploited to improve mobility in saturated traffic conditions via application of gating measures, based on an appropriate simple feedback control structure. As a case study, the proposed methodology is applied to the urban network of Chania, Greece, using microscopic simulation. The results show that the total delay in the network decreases significantly and the mean speed increases accordingly.     

Linking ocean container carrier capabilities to shipper–carrier relationships: a case study

ABSTRACT

As outsourcing and offshoring continue to expand, the ocean container industry serves a critical and still increasing role in supporting global trade. Yet, perceived commoditization and intense price competition among ocean container carriers limit opportunities for competitive advantage and formation of long-term shipper–carrier relationships. This environment ultimately yields an unhealthy industry that threatens the stability of global supply chains. Extant literature provides limited insight into how carriers can build strong relationships with shippers to overcome the short-term, transactional-orientation of the industry. Examining a case study of a major ocean container carrier, we apply structural equation modeling to shipper survey data to explore how carrier operational, service, and pricing capabilities influence the strength of the long-term shipper–carrier relationship. Furthermore, we identify unique clusters of shipper needs, helping the carrier understand when and how to promote a particular portfolio of capabilities to customers.     

Appraisal of investments in European nodal centres for goods – freight villages: A comparative analysis

The paper presents and analyses appraisal methods used for the assessment of potential investments in Nodal Centers for Goods (also called Freight Villages), which constitute an essential element of the Trans-European Network for Intermodal Transport. A methodological procedure is applied to identify the underlying factors that influence the choice of an appraisal method, without assessing or comparing the appraisal methods themselves. Following this procedure, issues addressed by the methods are grouped into three broad dimensions and with the use of non-parametric statistical tests, existing relationships are identified between nodal centres' characteristics, the appraisal methods, as well as the actors involved in the decision process. On applying the above procedure to European Nodal Centres for goods, it is found that the choice of appraisal method and the decision criteria for the investment are linked primarily to the nodal centre's size, catchment area, and the support or absence of political approval for the investment. The results of the analysis can be particularly useful at the policy making level, serving as non-formal "qualitative guidelines" to identify the appraisal method to be applied, as well as the options and impacts to be considered. This revised version was published online in June 2006 with corrections to the Cover Date.