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671.
The public presently owns, or has the right to use, a substantial portion of the nation's ocean beaches. However, the public cannot, in fact, use many of these beaches because there is no legal access to them. As the coast develops, more and more areas become closed to the public. The states are now being encouraged to plan for access to the beaches; there are a number of tools and techniques at their disposal. 相似文献
672.
Paul R. Tétreault Ahmed M. El-Geneidy 《Transportation Research Part A: Policy and Practice》2010,44(6):390-402
In recent years, several transit agencies have been trying to be more competitive with the automobile to attract choice riders. Transit agencies can only be competitive if they can provide services that are reliable, have a short access and egress time, and have run times that are comparable to automobiles. Several transit agencies try to be competitive through offering faster service, such as limited-stop (express) bus service. This study uses AVL and APC data, in addition to a disaggregate data obtained from a travel behavior survey, to select stops and estimate run times for a new limited-stop service that will run parallel to a heavily used bus route (67 Saint-Michel) in Montréal, Canada. Three different scenarios are developed based on theory and practice to select stops to be incorporated in the new limited service. The time savings for each scenario are then evaluated as a range and a fourth scenario is developed. A limited-stop service is recommended based on selecting stops serving both directions of the route, major activity points and stop spacing. This study shows that implementing a limited-stop service would yield substantial time savings for both, the new limited service and the existing regular service running in parallel. 相似文献
673.
M. T. Addico 《Maritime Policy and Management》2013,40(2):121-132
This paper looks at how the Shippers‘ Council could operate to make shipping cost-effective and to play its role as a servant of trade—a servant of the shippers. It looks at the key problems that confront the shipper requiring intervention by a Shippers‘ Council and surveys how the organization of the Shippers’ Council effectively handles problems. The final sections draw conclusions which could contribute to increasing the efficiency of Shippers' Councils, as well as improving the understanding of the Councils as managers of the demand side of shipping. 相似文献
674.
Transportation demand modeling has evolved in scope, theory, and practice in the many decades since the US Bureau of Public Roads pioneered home interview transportation studies in metropolitan households in the early 1940s. The major currents of these developments are discussed in the present paper through consideration of the changing role of the individual—as a source of data, as a unit of analysis, and as the intended beneficiary. In addition to reviewing this history we raise, but are unable to resolve, a growing current concern, namely how the public interest can be best served when the transportation data of greatest value is collected by private entities. 相似文献
675.
Stephen T. Atkins 《运输评论》2013,33(4):307-325
The paper considers the performance of land‐use transportation study techniques over the past ten years. Although primarily viewed from a U.K. perspective the paper reviews matters of principle which are of international relevance. The changing context and tasks for modelling are reviewed and the current role and applications of such models considered. The capability of established models to meet these changing requirements is examined. Attention is drawn to model specification and the ability of models both to represent new policies and to predict traveller responses to them. Also relevant is the ‘behavioural’ theme and the way in which survey technique conditions the data obtained. Particular emphasis is placed on the accuracy of modelling, both in the representation of base year travel patterns and in the forecast mode. The inherent uncertainty concerning input data is discussed and the frequent failures to establish model validity are noted. Three crises for U.K. transportation planning practice are identified: the ageing of data bases, the accuracy and validity of models and the current changes to the institutional context of transport planning in the U.K. Some potential remedies for the first two difficulties are proposed. It is concluded that only the last ‘crisis’ represents a real threat to the application of rational methods in transportation planning. 相似文献
676.
677.
678.
David Bauner 《Transportation Research Part A: Policy and Practice》2011,45(5):375-388
In the beginning of the 1970s, the economies of USA and Japan were growing fast and environmental pollution was increasing to alarming levels. As passenger car emissions were found to be significant and rapidly increasing, their reduction was specially targeted. Following a bill passed by US Congress in 1968, requirements were set in 1970 for the vehicle manufacturers to reduce the emissions of carbon monoxide (CO) and hydrocarbons (HC) with 90% by 1975, and nitrogen oxides (NOx) with 90% by 1976. These requirements were soon adapted to the Japanese regulatory framework, and were known in both countries as the “Muskie Act” or “Muskie Law” after the senator who developed the original bill.The new requirements spurred tremendous research and development efforts. Car manufacturers and research institutions in USA, Japan and Europe investigated and developed alternative solutions, including gas turbine and steam engine vehicles. California, the USA state with the most severe air quality problems and the only state at the time allowed to establish more strict requirements than federal regulation, established requirements implying the use of oxidation catalysts in 1975 and three-way catalysts (TWC’s) in 1977. Japan as a nation adopted similar requirements 1976 and 1978. Export of cars from Japan to USA increased rapidly. The rest of USA adopted emission standards similar to California’s only in 1981, timing USA vehicle sales rebound after the energy crisis and grave economic downturn. Strict requirements were thus established only after more than a decade of civic and legal processes between federal authorities, the car manufacturers and NGO’s.The history of vehicle development is one of cooperation and competition. This paper argues that the international cooperation on different levels of society (government, industry and science) together with commercial competition between the two countries was strong, continuous and instrumental in enabling the development of technology, appropriate regulation and infrastructural changes and thus created a market for cleaner cars and effectively reduced emissions from the growing vehicle fleet. In other words, the introduction of TWCs was reinforced by the simultaneous development of mitigating technology in two car producing countries competing for market space. 相似文献
679.
In 2000, the city of Bogotá, Colombia embarked on a grand land use and transportation system experiment. The transformation of Bogotá included building the TransMilenio Bus Rapid Transit (BRT) system, a city-wide system that offers speed and convenience similar to that of an underground metro. TransMilenio is widely regarded as a success, and cities around the world are planning or building similar systems. In this paper, we use a repeated cross-section labor market dataset to assess whether access to the new BRT system affects the incomes of those who live in station area neighborhoods. Our results indicate that the opening of the TransMilenio system was associated with increased income for those living near—but not immediately adjacent to—trunk line stations. This relationship is strongest in the lower and middle-income range. There are at least two possible explanations for this result: 1. existing residents earn higher wages, or 2. higher income workers move to the neighborhood. Our data do not allow us to distinguish clearly between them, but available evidence suggests that much of the effect is likely due to relocation. Our results stand in contrast to prior work, which has largely suggested that improvements in public transit will tend to reduce wages in station areas. 相似文献
680.
L.L. Loseto G.A. Stern D. Deibel T.L. Connelly A. Prokopowicz D.R.S. Lean L. Fortier S.H. Ferguson 《Journal of Marine Systems》2008,74(3-4):1012
Mercury (Hg) levels in the Beaufort Sea beluga population have been increasing since the 1990's. Ultimately, it is the Hg content of prey that determines beluga Hg levels. However, the Beaufort Sea beluga diet is not understood, and little is known about the diet Hg sources in their summer habitat. During the summer, they segregate into social groups based on habitat use leading to the hypothesis that they may feed in different food webs explaining Hg dietary sources. Methyl mercury (MeHg) and total mercury (THg) levels were measured in the estuarine-shelf, Amundsen Gulf and epibenthic food webs in the western Canadian Arctic collected during the Canadian Arctic Shelf Exchange Study (CASES) to assess their dietary Hg contribution. To our knowledge, this is the first study to report MeHg levels in estuarine fish and epibenthic invertebrates from the Arctic Ocean. Although the Mackenzie River is a large source of Hg, the estuarine-shelf prey items had the lowest MeHg levels, ranging from 0.1 to 0.27 μg/g dry weight (dw) in arctic cisco (Coregonus autumnalis) and saffron cod (Eleginus gracilis) respectively. Highest MeHg levels occurred in fourhorn sculpin (Myoxocephalus quadricornis) (0.5 μg/g dw) from the epibenthic food web. Beluga hypothesized to feed in the epibenthic and Amundsen Gulf food webs had the highest Hg levels matching with high Hg levels in associated food webs, and estuarine-shelf belugas had the lowest Hg levels (2.6 μg/g dw), corresponding with the low food web Hg levels, supporting the variation in dietary Hg uptake. The trophic level transfer of Hg was similar among the food webs, highlighting the importance of Hg sources at the bottom of the food web as well as food web length. We propose that future biomagnification studies incorporate predator behaviour with food web structure to assist in the evaluation of dietary Hg sources. 相似文献