Determinants of crew injuries in vessel accidents

This study investigates determinants of the number of non-fatal crew injuries, fatal crew injuries and missing crew in freight ship, tanker and tugboat vessel accidents based upon individual accidents investigated by the US Coast Guard for the 1991-2001 period. Poisson and negative binomial regression estimates suggest that: (1) freight ship and tanker non-fatal injuries are higher when the vessel is moored or docked and during high winds and cold temperatures; (2) tugboat non-fatal injuries are higher during poor visibility; (3) freight ship fatal injuries increase with vessel age and tanker and tugboat fatal injuries are higher for fire and capsize accidents, respectively; and (4) freight ship missing crew increase with vessel age and tugboat missing crew are higher for fire and lake accidents.     

Analysis of Work Zone Traffic Behavior for Planning Applications

Abstract

Understanding work zone traffic behavior is important for the planning and operation of work zones. The objective of this paper is to develop a mathematical model of work zone traffic flow elements by analyzing the relationships between speed, flow, and density that can be used to estimate the capacity of work zones. Traffic flow data were collected from 22 work zone sites on South Carolina interstate highways. The scatter plots of the collected data demonstrate that the relationship between speed and density does not follow Greenshields’ linear model. A non-linear hyperbolic model was developed to describe the relationship between speed and density. Using this model the capacity of a work zone was estimated to be 1550 passenger cars per hour for 2-lane to 1-lane closures. Adjustments to this capacity value to consider other types of vehicle as well as the work zone intensity are provided. Highway agencies can use this estimated capacity along with anticipated traffic demand to schedule work zone operations to avoid long periods of over-saturation.

The tapered approach to work zone lane closures used by South Carolina is similar to methods used in work zones throughout the world. The authors believe that the methodology described in this paper for modeling work zone traffic as well as estimating work zone capacity is transferable to other countries. The conversion of actual volumes to passenger car equivalents may have to be modified due to the significant differences in traffic makeup between the United States and other countries.     

Determinants of vessel-accident bunker spills

The study investigates determinants of vessel-accident bunker fuel spillage. A vessel-accident bunker spillage equation is estimated using Tobit regression and data of individual non-oil-cargo vessel accidents that were investigated by the US Coast Guard during 2001–2008. The results indicate that the bunker spillage of a freight ship and an offshore supply vessel accident will be greater than that of a passenger ship accident. Also, the bunker spillage of a non-oil-cargo vessel accident will be greater if the vessel accident is an abandonment and occurs at night, but less if the accident involves a vessel that has diesel propulsion and even less if the vessel has both diesel propulsion and a steel hull.     

Determinants of the damage cost and injury severity of ferry vessel accidents

This study investigates determinants of the property damage cost and injury severity of ferry vessel accidents. Detailed data of individual ferry vessel accidents for the 11-year timeperiod 1991–2001 that were investigated by the U.S. Coast Guard are used to estimate ferry-vessel accident property damage cost and injury severity equations. Tobit regression is used to estimate the former equation and the ordered probit model is used to estimate the latter. Property damage costs include damage costs to the vessel itself, its cargo and contents, and other-property damage (e.g., damage to pier structures and waterfront facilities). Injury severity for a ferry vessel accident is measured as an ordinal variable — no injuries, non-fatal injuries and fatal injuries. Damage cost and injury severity of individual ferry vessel accidents are expressed as functions of the type of vessel accident, vessel characteristics, vessel operation phase, weather/visibility conditions, type of waterway, type of vessel propulsion, type of vessel hull construction and cause of vessel accident. The property damage estimation results suggest that allision, collision and fire ferry vessel accidents incur more vessel property damage cost per vessel gross ton than other types of accidents. The injury severity estimation results suggest that injury severity is greater when the ferry vessel accident is caused by human error as opposed to vessel and environmental factors.     

Vessel accident oil-spillage: Post US OPA-90

The vessel accident oil-spillage literature has focused on oil-cargo vessels, tankers and tank barges, implicitly assuming that these vessels incur greater accident oil-spillage than other (i.e., non-oil-cargo) vessels which just carry oil in their fuel tanks. This study investigates the validity of this assumption for the post US OPA-90 (Oil Pollution Act of 1990) period by investigating determinants of vessel accident oil-spillage, where one of the hypothesized determinants is type of vessel (including both oil-cargo and non-oil-cargo vessels). Tobit regression estimates of vessel accident oil-spillage functions suggest that tank barges have incurred greater in-water and out-of-water oil-spillage for the post OPA-90 period than non-oil-cargo vessels; alternatively, tankers have not incurred greater out-of-water (in-water) oil-spillage than non-oil-cargo vessels (except for freight ships). The policy implication is that greater attention needs to be given to reducing tank barge accident oil-spillage in the post OPA-90 period.     

Vessel traffic service systems: cost-recovery alternatives

This paper investigate cost-recovery alternatives for US federally-operated vessel traffic service (VTS) systems. These include those currently used or have been used by VTS and 'VTS-like' systems and other feasible, but not used herefore, alternatives, a federal trust and a federal VTS user-fee structure. Three federal trust funds exist whose waterway-related earmarked revenues could also be earmarked for VTS systems. A federal VTS user-fee structure while raising revenue to finance VTS systems is not expected to be detrimental to the competitiveness of VTS ports nor to the vessel operators that call if their cost-savings exceed fees paid.     

Development of a sensor system for traffic data collection

Although many types of traffic sensors are currently in use, all have some drawbacks, and widespread deployment of such sensor systems has been difficult due to high costs. Due to these deficiencies, there is a need to design and evaluate a low cost sensor system that measures both vehicle speed and counts. Fulfilling this need is the primary objective of this research. Compared to the many existing infrared-based concepts that have been developed for traffic data collection, the proposed method uses a transmission-based type of optical sensor rather than a reflection-based type. Vehicles passing between sensors block transmission of the infrared signal, thus indicating the presence of a vehicle. Vehicle speeds are then determined using the known distance between multiple pairs of sensors. A prototype of the sensor system, which uses laser diode and photo detector pairs with the laser directly projected onto the photo detector, was first developed and tested in the laboratory. Subsequently this experimental prototype was implemented for field testing. The traffic flow data collected were compared to manually collected vehicle speed and traffic counts and a statistical analysis was done to evaluate the accuracy of the sensor system. The analysis found no significant difference between the data generated by the sensor system and the data collected manually at a 95% confidence interval. However, the testing scenarios were limited and so further analysis is necessary to determine the applicability in more congested urban areas. The proposed sensor system, with its simple technology and low cost, will be suitable for saturated deployment to form a densely distributed sensor network and can provide unique support for efficient traffic incident management. Additionally, because it may be quickly installed in the field without the need of elaborate fixtures, it may be deployed for use in temporary traffic management applications such as traffic management in road work zones or during special events.     

Port pricing: a cost axiomatic approach

The earlier port pricing literature argued that port prices should be based uponk marginal cost pricing. However, recent literature suggests that a conflicts would arise between marginal cost pricing and full cost recovery at ports. Further, problems arise in determining or estimating marginal costs. A price structure that addresses the problems of port marginal cost pricing is cost axiomatic pricing, given the goals, objectives and constraints of ports. Fairness and cost efficiency cost axioms for ports are considered. A methodology for determining cost axiomatic prices for a marine container terminal is presented.     

Urban activity spaces: Illustrations and application of a conceptual model for integrating the time and space dimensions

This work extends the conceptual argument for the use of ellipses to portray activity spaces and offers one example of how the ellipse construct can be used to analyze urban travel characteristics, based on observed trip making behavior and socio-economic variables. A problem in characterizing activity spaces has been in integrating the time and space dimensions into the same analytical framework while maintaining an understandable graphical representation of the space-time geographies envisioned by Hagerstrand and others. The ellipse allows this, as well as providing several quantifiable measures to be used for analyzing and characterizing activity spaces and urban travel behavior. In the current application, analysis of variance is used to analyze the resulting elliptic variables of 653 travelers. The results indicate that home location and household size are important factors in determining activity space characteristics and that the ellipse variables provide a different and useful approach for understanding urban travel behavior.     

U.S. public transit earnings, employment and privatization

This paper uses individual worker and municipal information to examine privatization's influence on public transit workers' earnings and employment. OLS findings on labor earnings reveal that privatization is associated with an erosion of the public transit union premium. These labor earning findings do not change when correcting for privatization heterogeneity, as unobserved worker characteristics do not differ with differing levels of municipal privatization of public transit services. The employment findings reveal that union public transit workers are more likely to be employed in the public sector and this union-nonunion employment probability differential, declines with increasing levels of privatization. This employment result is interpreted as suggesting that labor cost savings from privatization can be derived from the enhanced employment of relatively low wage nonunion workers in the public sector of public transit services.