The abatement cost function for a representative vehicle inspection and maintenance program

Mandatory inspection and maintenance programs require on-road vehicles to be tested regularly and repaired if they are not in compliance with air emission regulations. We estimate the abatement cost function for a representative inspection and maintenance program. This is done by constructing a model of the statistical process that leads to non-compliance, parameterizing the model, and then by simulating the total abatement cost function. The model predicts that the marginal abatement cost for a major representative program is so high that even a small reduction in the abatement target leads to substantial cost savings to motorists. In addition, even for quite high levels of the abatement target, the optimal minimum testing age is substantially higher and the frequency of testing is much lower than is common in many jurisdictions.     

A human factors systems approach to examining oil spills in tankbarge operations: analysis and reappraisal of management policies

An important problem in the US maritime industry is the large number of oil spills that occur as a result of oil transfer operations involving tankbarges. Recently, the US Coast Guard initiated a new programme entitled Prevention Through People that represents a concerted effort towards preventing human errors leading to casualities and oil spills. The purpose of the study reported in this paper was to explore tankbarge oil transfer operations from the standpoint of regulatory, management, and operational perspectives in order to determine the likelihood that this new initiative will indeed result in a better understanding of the causal basis for human error in these operations and, more generally, in the maritime industry. The results of this novel study are discussed and summarized in terms of four broad classes of recommendations.     

The relationship among highway geometrics,traffic-related elements and motor-vehicle accident frequencies

This research provides a demonstration of a statistical model of accident frequency that can eventually be used as part of a proactive program to allocate safety-related highway improvement funds. Negative binomial regressions of annual accident frequency on sections of principal arterials in Washington State were estimated using data from two years (1992 and 1993). In all, 31306 observations were used in model estimation (annual accident frequencies on specific sections of highway). Our estimation results isolated the effects of various highway geometric and traffic characteristics on annual accident frequency. Subsequent elasticity computations identified the relative importance of the variables included in our specifications. The findings show that the negative binomial regression used in this paper is a powerful predictive tool and one that should be increasingly applied in future accident frequency studies.     

混凝土试验的重要性

混凝土由于其适应性强,长期以来被选作重大隧道工程的材料,这就使得严密而准确的混凝土试验显得十分重要.由于不经过现场的准确试验,拌合物的性质将会在极大的范围内变化,其结果是产生质量问题和安全度的降低.     

Route choice and the value of commuting time: An economic model of dichotomous choice

This paper presents an economic model of generalized travel cost and provides an empirical study of the parameters of the cost function. The route-choice model that is estimated combines McFadden's theory of qualitative choice behavior with a function for the value of travel time in which total trip time and the income level are assumed to influence the marginal value of time. The empirical results indicate that, for a sample of commuters in the Chicago metropolitan area in 1972, the value of time is a positive function of total trip time, but is not a function of income.     

The analysis of travel and emission impacts of travel demand management strategies using activity-based models

This paper demonstrates, tests and shows the value of activity-based travel demand models and household sample enumeration forecasting techniques in evaluating the transportation and air quality impacts of travel demand management strategies. Using data from the Portland, Oregon metropolitan area, three transportation policies were evaluated both individually and in combination: transit improvements, pricing, and telecommunications. The activity-based models used in this testing represents a significant improvement to today's "four-step" sequential model systems by providing a deeper insight into the individual decision making process in response to transportation policies. A wider range of impacts is predicted, and indirect effects as well as synergistic effects of such policies are taken into consideration. These models are capable of providing the information needed to improve the linkage of transportation models with emissions and air quality analysis methodologies by improving the prediction of variables that are important to accurately estimating emissions and air quality impacts of transportation actions.     

Untangling process complexity in logistics delivery services with unpredictable service sequences: a mixed-method study of chemical tanker port calls

We explore the complexity issue relevant to a logistics service process characterized by unpredictable service stages and service sequences in the context of chemical tankers’ call in the Port of Houston. The operational dimensions of uncertainty and conflict surrounding process complexity are examined through a mixed-methods approach using both qualitative and quantitative data collected from the Port of Houston. We propose a taxonomy to classify several uncertainty and conflict factors emerged from our qualitative analysis, including structural conflict, structural uncertainty, infrastructural conflict, and infrastructural uncertainty. The case study findings are validated and triangulated by a quantitative analysis which quantifies the time and cost impacts of unproductive chemical tanker movement on port-call service performance. We contribute to the complexity theory by introducing four dimensions of process complexity to the stream of process-oriented logistics service research. These four complexity dimensions can be used by managers to untangle their process complexity. Our pseudo-service-stage based mapping technique will also be valuable for managers to visualize their service processes with unpredictable service sequences. Finally, we call for future research on synchronization across operational processes between service stages.     

Aesthetic markets and a new automated people mover

Research literature suggests that aesthetic response toward a transportation system may be colored by non-aesthetic values. Photographic depictions of downtown street scenes with and without automated people mover guideways were shown to various community groups. Measures of external utilities—stakes in the local community and in public transportation—bore no relationship to aesthetic assessments of either guideway scenes or street scenes without a guideway. In contrast, aesthetic background and interests depressed evaluations of both guideway and non-guideway scenes. Aesthetic background evidently influences aesthetic assessments of elevated guideways in urban streets far more than do non-aesthetic utilities. This suggests that planners of new transportation systems need to address aesthetic impacts apart from other impacts and that aesthetic criteria will be applied more stringently by some community groups than by others.     

A nested logit model of automobile holdings for one vehicle households

This paper presents a model of automobile choice by single vehicle households. This effort is distinguished from previous disaggregate automobile holdings models primarily by the use of the nested logit model rather than the more restrictive multinomial logit model. We present a 2-step estimation technique that provides consistent and asymptotically efficient parameter estimates, yet is tractable for very large choice sets. Using disaggregate data on 237 one-vehicle households we estimate the unknown parameters on an automobile choice model containing 785 individual makes, models and vintages of passenger vehicles.