Congestion relief toll tunnels

Changing urban land-use patterns have reduced the importance of traditional downtowns as the origin and destination of numerous vehicular trips. Much traffic on downtown-area freeways seeks merely to get past downtown, thereby worsening the level of congestion for those seeking access to downtown.A number of European cities have begun to develop a new type of transportation facility: congestion-relief toll tunnels in downtown areas. These projects appear to be economically feasible largely or entirely from premium-price tolls paid by users. Hence, they are being developed by private consortia, operating under long-term franchises from government. Other keys to the feasibility of such projects are peak/off-peak pricing structures (congestion pricing), nonstop electronic toll collection, and restriction of use to auto-size vehicles only (to reduce tunnel dimensions and therefore capital investment).Preliminary analysis indicates that congestion-telief bypass runnels for downtown Los Angeles and San Francisco would be economically feasible as private business ventures, if developed along European lines. Similar approaches might be applied to other controversial freeway projects in both cities, and to restructuring Boston's huge and controversial Central Artery/Tunnel project.Congress has already authorized public-private partnerships of this type, permitting private capital and private owner/operation to be used, both for new projects and to rebuild existing highway, bridge, and tunnel facilities. Six states and Puerto Rico have enacted private-tollway legislation under which such projects could be developed and operated.This type of project should be politically feasible, since it offers a way to make significant transportation improvements in impacted downtowns with little or no public funding. While transit proponents may oppose the construction of toll tunnels, highway users are likely to support such projects, and some environmental groups may support this method of implementing congestion pricing in urban areas, because of its potential for reducing air emissions.     

Meroplankton abundance in the Northeast Water Polynya: Insights from oceanographic parameters and benthic abundance patterns

We investigated meroplankton (planktonic larvae of benthic organisms) abundance and distribution in the Northeast Water (NEW) Polynya, located on the northeast coast of Greenland, from July 15 to August 15, 1992. Meroplankton was present at all sites visited (0.03–84.83 individuals per m³); at one station meroplankton comprised 8.28% of total zooplankton. Total meroplankton abundance was correlated with total zooplankton abundance and total benthic infaunal abundance but was not correlated with either microscopic carbon concentration or primary productivity. Examination of distribution data for barnacle nauplii and adults indicated that both adults and larvae were concentrated at the same locations. Patterns of distribution were also examined for stelleroid plutei, polychaete larvae and trochophores. There were distinct geographic patterns in total and class-specific meroplankton distributions, with maximal abundances occurring over the Belgica Bank and in the eastern regions of the Westwind Trough and minimal abundances in the Belgica Trough. The apparent control of meroplankton distribution by the hydrography of the region, coupled with the correlation between meroplankton, zooplankton and adult infaunal abundance, reinforces the hypothesis that hydrography plays a major role in controlling the distribution of biota in the NEW polynya (Ambrose and Renaud, 1995; Ashjian et al., 1995, 1997-this volume; Smith et al., 1995; Piepenburg et al., 1997-this volume).     

Introducing congestion pricing on a new toll road

This paper proposes a demonstration project to test the effectiveness of congestion pricing in an urban area. It reviews the general theoretical case for such pricing and summarizes recent international interest in congestion pricing. Next, it sets forth the reasons why demonstration projects are needed, both to add to our knowledge about how effective congestion pricing may prove to be, and to address political and other public-acceptance barriers to implementation of the concept. The paper then defines a specific proposed test site for congestion pricing: a new toll road being planned for Orange County, California. It is proposed that instead of charging flat-rate tolls, the transportation agency could charge peak and off-peak tolls, increasing the level of the peak charge each year over a period of up to 10 years unless or until toll revenues decline below the levels forecast under the flat-rate toll alternative. Measurements of traffic flow and ride-sharing behavior would be made, as well as calculations of emission-reduction effects. The paper concludes with a brief discussion of marketing and political considerations involved in conducting such a demonstration.Abbreviations ARB Air Resources Board - AVI Automatic Vehicle Identification - CDMG Corridor Design Management Group - HOV High-occupancy vehicle - SJHTC San Joaquin Hills Transportation Corridor - TCA Transportation Corridor Agency - VMT Vehicle miles traveled     

Transportation survey and rideshare matching model for rural communities

A simple and flexible low technology rideshare matching model was developed for a rural area. A brief survey form provided information on distance to work, fuel consumption and currently used transportation mode in conj unction with information on employment location and work schedule. The model developed used a computerized system for proximity matching of potential ride sharers. An existing computer program with detailed modifications was used for data analysis. Unlike other rideshare matching programs, this model relies on grouping by community names to match riders.     

The coastal barrier resources act of 1982: An assessment of legislative intent,process, and exemption alternatives

Recent coastal barrier legislation demonstrates a growing national concern to protect fragile undeveloped coastal barriers and to prevent the expenditure of federal monies used in promoting their development. The Coastal Barrier Resources Act of 1982 bases designations of undeveloped coastal barriers on previous federal legislation and Department of the Interior rule‐making. This paper examines the legislative intent of Congress and how it was interpreted through the designation process. Alternative strategies to achieve exemption from the Coastal Barrier legislation are discussed as a process, and an analysis is made of an exemption as it occurred in Texas.     

Failure modes in the maritime transportation system: a functional approach to throughput vulnerability

Maritime Transportation Systems (MTSs) are essential for world trade; it is crucial to understand how these systems may fail, to be able to maintain their capacity. In this paper, the MTS is seen as a throughput mechanism; a technical system which serves its purpose by moving goods for its dependents. Understanding which key functions and capabilities are prerequisite for the ability to move goods, the loss of which are the failure modes, allows for the creation of a ‘business continuity plan’ for the MTS. Through two surveys and interviews with maritime transportation industry stakeholders, it was observed that while stakeholders in the industry have a solid focus on frequent operational risks, there is a lack of awareness of vulnerabilities, as well as methods for addressing and planning for low-frequency high-impact disruption scenarios. The presented approach provides a structured set of matrices of the key functions of the MTS, allowing stakeholders to increase the system's resilience through preparing to restore this limited number of critical functions.     

An econometric analysis of deficiencies noted in port state control inspections

The factors to consider in selecting which vessels to board for port state control (PSC) inspections are crucial. This paper tries to identify these factors using 4080 reported PSC inspections from the Swedish Maritime Administration for the period 1996-2001. It relies on count data models and compares results from the Poisson, negative binomial, random effect and random parameters models. The results suggest that three factors are the main determinants of the number of reported deficiencies: the age at inspection, the flag of registry and the type of ships. Conversely, the year when the inspection occurs does not seem to be a significant factor. Estimations also stress that the relationship between the age at inspection and the number of deficiencies detected is not similar for different vessel types. For instance, the number of deficiencies detected decreases for chemical carriers and Ro-Ro passenger vessels older than 25 and 22 years old, while for instance the effect is rather small for tanker and bulk carriers and only occurs when vessels are older than 35 years.     

世界公路桥梁检测方法研究

美国运输委员会的主要目标之一是提高我们国家的道路安全.针对这一目标,联邦、州和地方交通机构一致认为检测我们的近600 000座桥梁是非常重要的.这些机构每年投入大量资金到桥梁检测方面的行动.确保质量,使得我们的桥梁检查计划维持在最高的水平,且资金的利用尽可能有效.通过美国桥梁检查计划收集的数据不仅用来确保我们的桥梁对公众来说是安全的,而且有助于构建编制桥梁养护、维修、复原和更换的基础.因此,确保高质量的数据收集是在检测过程中进行的,这是极其重要的.     

Effects of sediment resuspension on organic matter processing in coastal environments: A simulation model

A model, constructed using STELLA™, was used to simulate changes in standing stocks and flows of organic matter resulting from sediment resuspension in shallow coastal environments. Previous studies suggested that resuspension may determine the sites and rates of organic matter mineralization in shallow environments (Hopkinson, 1985, 1987). Those studies predicted that resuspended organic material could exert an enhanced demand on dissolved oxygen. Our model results support this hypothesis. Total system metabolism receives increasing contributions from the water column as settling rate decreases. Water column respiration also increases relative to benthic respiration as the frequency and intensity of resuspension events increases. This is driven by higher specific degradation rates in the water column than in the benthic environment. Furthermore, overall respiration (benthic + pelagic) increases in response to resuspension.