HOLDING DECISIONS FOR CORRELATED VEHICLE ARRIVALS AT INTERMODAL FREIGHT TRANSFER TERMINALS

A vehicle holding method is proposed for mitigating the effect of service disruptions on coordinated intermodal freight operations. Existing studies are extended mainly by (1) modeling correlations among vehicle arrivals and (2) considering decision risks with a mean-standard deviation optimization model. It is shown that the expected value of the total cost in the proposed formulation is not affected by the correlations, while the variance can be miscomputed when arrival correlations are neglected. Some implications of delay propagation are also identified when optimizing vehicle holding decisions in real-time. General criteria are provided for determining the boundary of the affected region and length of the numerical search, based on the frequency of information updates. Theoretical analyses are supported by three numerical examples.

STATISTICAL METHODS FOR ADVANCED ECONOMETRIC MODELS WITH APPLICATIONS TO VEHICLE HOLDING AND SPEED QUANTILES DISTRIBUTION

This dissertation proposes statistical methods to formulate, estimate and apply complex transportation models. Two main problems are part of the analyses conducted and presented in this dissertation. The first method solves an econometric problem and is concerned with the joint estimation of models that contain both discrete and continuous decision variables. The use of ordered models along with a regression is proposed and their effectiveness is evaluated with respect to unordered models. Procedure to calculate and optimize the log-likelihood functions of both discrete-continuous approaches are derived, and difficulties associated with the estimation of unordered models explained. Numerical approximation methods based on the Genz algortithm are implemented in order to solve the multidimensional integral associated with the unordered modeling structure. The problems deriving from the lack of smoothness of the probit model around the maximum of the log-likelihood function, which makes the optimization and the calculation of standard deviations very difficult, are carefully analyzed. A methodology to perform out-of-sample validation in the context of a joint model is proposed. Comprehensive numerical experiments have been conducted on both simulated and real data. In particular, the discrete-continuous models are estimated and applied to vehicle ownership and use models on data extracted from the 2009 National Household Travel Survey. The second part of this work offers a comprehensive statistical analysis of free-flow speed distribution; the method is applied to data collected on a sample of roads in Italy. A linear mixed model that includes speed quantiles in its predictors is estimated. Results show that there is no road effect in the analysis of free-flow speeds, which is particularly important for model transferability. A very general framework to predict random effects with few observations and incomplete access to model covariates is formulated and applied to predict the distribution of free-flow speed quantiles. The speed distribution of most road sections is successfully predicted; jack-knife estimates are calculated and used to explain why some sections are poorly predicted. Eventually, this work contributes to the literature in transportation modeling by proposing econometric model formulations for discrete-continuous variables, more efficient methods for the calculation of multivariate normal probabilities, and random effects models for free-flow speed estimation that takes into account the survey design. All methods are rigorously validated on both real and simulated data.

HOLDING HANDS WHILE PARTING WAYS: EXAMINING ALLIANCE TREATY RENEGOTIATION

This study investigates the renegotiation of security alliances, specifically the structural conditions surrounding their revision. Although the field of international relations offers a rich discussion of the formation and violation of alliance treaties, few scholars have addressed the reasons why alliance members amend security obligations. After the formation of an alliance, a member may become dissatisfied owing to changes in the external and domestic security environments. A failure to address this discontent increases the risk of alliance breakdown. Members manage their alliance relationship through a negotiation process or intra-alliance bargaining in the search for a new arrangement that can endure. Factors that help to show commitment to the alliance and communicate a set of feasible solutions are crucial if members are to find a mutually acceptable arrangement. By taking these factors into account, allies are more likely to revise an existing treaty. Examining a set of bilateral alliances dating from 1945 to 2001, this research demonstrates that public requests for renegotiation compel allies to change the status quo. It is found that alliance-related fixed assets and the formation of external alliances increase the likelihood of treaty revision, though institutionalization of an alliance does not help to resolve interest divergence. In addition, this study examines the strategy of delay in intra-alliance bargaining. Allies may postpone a dispute by ignoring it while working to maintain the alliance. Tension among allies thus increases, but the alliance endures. I examine three alliances in order to illustrate this renegotiation process. Among these, the Anglo-Japanese alliance demonstrates two successful renegotiations that prolonged a wavering alliance relationship; the Sino-Soviet alliance is an example of failure owing to the lack of substantive cooperation; and the US-Taiwan alliance during the 1970s demonstrates successful use of a strategy of delay that appeases a dissatisfied member.