Decomposing travel times measured by probe-based traffic monitoring systems to individual road segments

In probe-based traffic monitoring systems, traffic conditions can be inferred based on the position data of a set of periodically polled probe vehicles. In such systems, the two consecutive polled positions do not necessarily correspond to the end points of individual links. Obtaining estimates of travel time at the individual link level requires the total traversal time (which is equal to the polling interval duration) be decomposed. This paper presents an algorithm for solving the problem of decomposing the traversal time to times taken to traverse individual road segments on the route. The proposed algorithm assumes minimal information about the network, namely network topography (i.e. links and nodes) and the free flow speed of each link. Unlike existing deterministic methods, the proposed solution algorithm defines a likelihood function that is maximized to solve for the most likely travel time for each road segment on the traversed route. The proposed scheme is evaluated using simulated data and compared to a benchmark deterministic method. The evaluation results suggest that the proposed method outperforms the bench mark method and on average improves the accuracy of the estimated link travel times by up to 90%.     

An economic model for sustainable harbor trucking

Truck emissions at a port may have a severe impact on neighbors, resulting in a politically sensitive sustainability issue for the port management. Strict emissions controls may adversely affect throughput whereas the lack of strict controls will be unacceptable to local citizens and environmental interests. We develop an economic model minimizing cost of truck emissions control and collateral production changes and apply it to decision making for a port seeking to meet a throughput goal while also attempting to satisfy an emissions constraint. Outcomes predicted by the model allow informed decisions about the impact of controls.     

连续壁坍孔对策探讨

本文检视影响连续壁槽沟开挖稳定因子,并以案例介绍采择「调高稳定液之质量与浓度」、「缩小连续壁单元长度、连续壁单元间钢筋不搭接等缩短开挖时间」、「提高稳定液与地下水位之液面差」、「灌浆地盘改良」等兼顾安全与经济性之设计、施工处理对策.     

World Maritime University

The issue of quality assurance in higher education is at the top of the agenda of universities throughout the world. For the World Maritime University, an institution with highly international staff and student bodies, a complex base of voluntary funding and isolated from any national or European system of education, the problem of defining quality and instituting a quality management system has been a particularly complex and vital task. Our quality standards are the key to our survival.     

The growth and patterns of international trade

Over the last 40 years, there has been an unprecedented growth in trade amongst countries, and the growth in trade shows no sign of slowing down. The increases in trade have put tremendous pressure on the maritime and port industries, and these industries have responded with innovations, investment, and greater productivity. International trade and maritime trade are synonyms, and an understanding of the determinants of international trade is central to understanding maritime trade. In this paper, we provide a review of the international trade literature with a focus on the determinants of trade and the evolution of trade modeling. We then present a broad overview of the extent and growth of trade in the context of primary determinants. The basic results are: (1) Trade is growing at a phenomenal rate; (2) Trade is dominated by relatively few countries who tend to remain dominant; (3) While trade of all products is growing, there are large differences in the growth rates, but yet, there is stability in the relative sizes of product markets; and (4) Over the last 40 years, trade has changed from major flows between the US and Europe to major flows between Asia and the US.     

The metropolitan planning organization role in the 1980s

A new study by the U.S. Advisory Commission on Intergovernmental Relations focuses on the adaptions in transit services, finances, institutions, and policy processes occasioned by current financial stress at all levels of government and by the devolution of national responsibilities to the state and local governments. This study found, in part, that (1) most metropolitan transportation planning organizations now are locally governed and staffed. (2) their planning is becoming increasingly isolated, less comprehensive, and shorter range. (3) some such organizations are experiencing strong pressure to decentralize or subregionalize, and (4) the desire for these organizations to exercise more effective areawide leadership is not matched with local approval of greater powers for them. The study concludes that informal coordination techniques or new powers granted by state legislatures are the two most likely facilitators of improved metropolitan transportation leadership in the 1980s.     

Book review

Coastal Management: Readings and Notes. Edited by Marc J. Hershman and James H. Feldmann. Institute for Marine Studies, Coastal Resources Program, University of Washington, Seattle (January 1979), 806 pp. $22.50 (paper bound).

Tobey L. Winters, Deepwater Ports in the United States: An Economic and Environmental Impact Study. N.Y. Praeger, 1977, 201 pages.     

Community Participation in Marine Protected Area Management: Wakatobi National Park,Sulawesi, Indonesia

Coral reef areas are threatened worldwide by growing populations, tourism development, and use of poison and dynamite in fishing in areas adjacent to the reefs. The designation of marine protected areas is one strategy for addressing these problems. Wakatobi National Park, established in Eastern Indonesia in 1996, contains approximately 50,000 ha of coral reefs and a resident population of Sama-Bajo people whose traditions and current livelihoods tie them closely to the sea. The present research, using participatory rural appraisal methods, focused upon the impact of the designation of the Marine Park on their lives and investigated the potential for public participation in park planning and management. The Wakatobi Park Management Plan does not address the needs and interests of local people. Priority should be placed on adaptation of park zoning and protection regulations to accommodate the livelihood requirements of indigenous communities.