The economics of double-hulled tankers

A cost-benefit analysis is conducted on the double-hull requirements for oil tankers in United States' waters contained in the U.S. Oil Pollution Act of 1990. The benefits of reduced spillage are compared with the increased construction and operations costs of double-hulled vessels. In the most probable scanario, the expected benefits are only 20% of the expected costs. Double-hulls do not even show a positive net present value with the most favorable assumptions. Even if double-hulls prevent all of the spillage that occurs due to collisions and groundings, and that the damage per gallon spilled is as extensive as in the ‘Exxon Valdez’ incident, the benefits are under half of the costs.     

On the use of mathematical programming in the evaluation of transport policies

This paper focuses on the evaluation processes by which decisions regarding transportation alternatives can be assisted. A multidimensional approach usually called multiple criteria decision making is required to represent the complexity of transportation policy and systems.

The multiple criteria decision making techniques can be divided into two groups. The first is based on a ranking scheme approach and the second on a mathematical programming approach.

A multiple objective mathematical programming procedure known as Goal Programming is presented. The authors examined the use of that procedure in real transportation problems.

The results suggest that multiple objective mathematical programming techniques in general do not appear to be appropriate in transportation policy analysis involving mutually exclusive alternatives. Their use can be limited to special cases in the private sector.     

Review of computer software for traffic engineers

The mid‐1970s saw the initiation of several lengthy research and development programmes in the United Kingdom which culminated in a range of software for the traffic engineer. The early 1980s brought cheap, powerful microcomputers, thereby enabling the facilities offered by the software to be exploited to the full. This article describes the range of programs now available and in common usage for the design and appraisal of traffic management schemes in the United Kingdom, and suggests a few of the areas where some research and development effort is still needed.     

Shipper's councils: role and responsibility—a western view

This paper first presents arguments for having public sector port authorities. They can deal, flexibly and permanently, with property rights within their own areas. They can plan and regulate port areas comprehensively. They can provide ‘public goods’. They can deal, in various ways, with externalities. They can promote efficiency, whether their own (if they operate as a comprehensive port) or that of the private sector (if they are largely landlords). For example, if their policy is to rely on the private sector to produce efficiency through competition then they can see to it that there actually is competition and not any kind of cartel or monopoly. Examples are cited where this last function has not been performed. The exception for single-user ports is noted.

Against them are the general disadvantages of public authorities (or bureaucracies)—though examples are cited where port authorities had very small staffs. The common instances of ‘market failure’ may thus be contrasted with those of ‘government failure’. Finally, a pragmatic approach is advocated, tailored to the needs and resources of the country in question. The increasing effect of the economies of scale in port technology, and its limitation on competition, is, however, noted and to be discussed in the next paper.     

Marginal cost pricing of ferry transportation: a practical application ∗

In this paper, in which the author attempts to redress the lack of attention by economists to ferry operation, a simple pricing model, based on marginal cost pricing, is developed.     

Commentaries

Abstract

This paper surveys the technologies available for constructing a pervasive, national‐scale road pricing system. It defines the different types of road pricing, the methods by which a vehicle’s position can be determined, and then examines possible pricing regimes in the context of their technological requirements and implications. The issue of enforcement and the distribution of pricing policies are considered, and further complexities are outlined. An examination of the security aspects of such systems is made, focusing particularly on the need to ensure privacy using technological, rather than solely procedural, methods. The survey concludes that a pervasive, national‐scale deployment is unlikely to be technically achievable in the short‐term.     

Understanding Recreational Boater Attitudes to Zoning in a Proposed Marine Protected Area

Although the success of marine protected areas (MPAs) and associated zoning schemes is largely dependent on stakeholder acceptance and support, there have been relatively few studies examining the response of recreational stakeholders to MPA proposals. This study investigates the response of recreational boaters to a proposed MPA in British Columbia, Canada. Using a structured questionnaire (n = 543) and a focus group (n = 6), the research examines the level of support for the concept of marine zoning and identifies key factors influencing support or opposition. Results indicate that a small majority of recreational boaters support the concept of marine zoning, but that there are areas of concern that ought to be addressed as MPA implementation proceeds. Support for zoning was strongly related to perceived benefits, particularly environmental benefits. Furthermore, perceived benefits overall were found to outweigh concerns as determinants of recreational boater support for zoning. Major dimensions of opposition included perceptions of over-regulation, loss of access for boating, and mistrust of the government. A suggestion is that such concerns may be mitigated through focused communication and meaningful involvement of boaters in the zoning process.     

In situ colonization of marine biofilms on UNS S32760 duplex stainless steel coupons in areas with different water qualities: Implications for corrosion potential behavior

In the presence of biofilms, stainless steels （SS） exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential （Eco,） behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor （an anthropogenically disturbed area） was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms （especially Navicula sp.） on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island （an undisturbed area）. The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.     

Industrial water dependency: The BCDC experience

The Bay Conservation and Development Commission (BCDC), has designated a number of shoreline sites around San Francisco Bay for exclusive use of water‐related industry. This is intended both to reduce future needs for Bay fill, and to reserve those waterfront sites needed for long‐term industrial growth. The Commission currently defines water‐related industries as those “requiring”; a shoreline site for water transportation. The Commission is now considering the use of an economic criterion for identifying water dependency. This involves comparisons of the uniquely water‐related benefits and costs to the firm to locate on the shoreline, as opposed to its location at an inland site. By limiting use of deepwater sites to those industries that are significantly water‐dependent under this criterion, long‐term economic efficiency is served, and the need for future Bay fill for industrial growth is reduced. The data and analysis required to implement an economic water‐dependency criterion do not appear to be a barrier to use of such a test in the regulatory process. Whereas water dependency is an important concern to BCDC, other factors, including environmental constraints, must also be weighed when evaluating industrial projects.     

Estimates of vertical mixing during a Lagrangian experiment off the Galician coast

An adjoint 1-D model was used to determine vertical diffusivity coefficients from temperature profiles collected within a filament escaping from the Galician coast following an upwelling event. The optimisation scheme ended with relatively high diffusivity values within the thermocline (9×10⁻⁵ m² s⁻¹). Such high values are relevant for biogeochemical exchanges between surface and deep waters in stratified areas.The optimised values were several orders of magnitude higher than the bulk of diffusivity measurements recorded with a free-falling device; however, the optimisation solution was consistent with the arithmetic mean of the measurements in the thermocline (7.7×10⁻⁵ m² s⁻¹), giving more weight to the few largest values. Below the thermocline, the data assimilation method failed because of the three-dimensional nature of the advective field of the upwelling system. Ignoring this advective forcing in the model led to estimates that were two orders of magnitude too high.The results suggest that turbulent mixing is a random process where a few intense events determine the average mixing that drives the long-term evolution of the water column structure. This statistical property is very important when one wants to use instantaneous diffusivity measurements for modelling purposes.