published journal article
published journal article
Cities worldwide are facing new challenges and opportunities with the proliferation of Unmanned Aerial Vehicles (UAVs), or drones. However, despite the increasing importance of managing drone activities at the local level, little is known about the extent to which cities adopt regulatory measures to deal with the challenges posed by this emerging technology and the factors that determine the local policy adopted. This study examines the dynamics of local drone policy adoption, focusing on California, which has the largest population of drones currently registered in the United States. A review of 482 California cities’ municipal codes shows evolving patterns of policy adoption over the last two decades, with a rapid expansion since 2015. Multivariate survival analysis indicates that policy adoption at the local level is shaped by both municipal capacity and motivation factors, including the actions of neighboring cities. The analysis also finds evidence of disparities associated with socio-demographics, calling for more attention to the variation in local policy responsiveness to technology-driven challenges and ways to support local efforts and their collaboration.
working paper
Many previous studies of transport tax reform have explicitly or implicitly assumed that the reform itself does not affect the marginal value of time. In this paper we consider a simple model with multiple trip purposes, commuting and non-commuting transport, to analyse the implications of transport tax reform for the value of time and for marginal external congestion costs. The theoretical analysis shows that transport taxes may both increase or reduce the value of time and it identifies the conditions under which either outcome will occur. The results further suggest that if a tax reform in the transport sector is accompanied by labour tax adjustments to reduce the distortionary cost of the tax system, the marginal value of time will typically increase. The implications of endogenous values of time for models of optimal externality taxes and studies of tax reform in the transport sector are empirically illustrated using a numerical model, calibrated using Belgian data. It is found that the impact of tax changes on the value of time is non-trivial. Moreover, many of the tax reform exercises considered simultaneously reduce traffic levels but raise marginal external congestion costs. The results of this paper suggest that incorrectly assuming exogenous time values may strongly bias optimal congestion taxes and lead to misleading welfare effects of transport tax reform.
conference paper
In this era of heightened competition many firms have turned to supply chain partners to collaborate to alleviate their operational inefficiencies and cut costs. Supply chain relationships are transforming to collaborative ventures, sometimes even with their competitors. In this paper we study the issues facing an electronic intermediary or a third party logistics company for achieving collaboration for transportation demands from a group of small to medium sized shippers in an Internet marketplace. We develop a methodology for studying the shipper collaboration problems and provide formulations for partly loaded and truckload shipments. The underlying cost allocation issues facing the collaborations are examined from a cooperative game theory perspective. We point out that finding stable cost allocation mechanisms are NP-Hard and develop simple heuristic cost allocation mechanisms.
research report
conference paper
published journal article
working paper
In contrast to existing theories of organizations that stress the vertical control of intraorganizational interaction, a structural perspective is discussed that emphasizes the networks of social interaction that develop horizontally and diagonally, as well as vertically, across the organization. As an example of this perspective, the effects of the hierarchical arrangement of positions, both in terms of the unequal number of individuals in vertical levels and in terms of the differential allocation of resources across vertical levels, is hypothesized to lead to differential rates of interaction across the organization. These effects of structural differentiation on networks of interaction are tested in a public bureaucracy, and the implications of differentiation for the formation of networks of interaction and resulting collective actions such as coalition formation are discussed.
MS Thesis
Due to heavy congestion and air pollutants emissions from the increase in container trucks traveling on the I-710, Caltrans and Metro have been looking into viable alternatives for solving these problems. The heavy health burden on residents of the areas surrounding the I-710 has been a cause for concern to these agencies for some time. In this study, I rely on microscopic traffic simulation and on operating modes (OpModes) lookup tables from MOVES to estimate changes in congestion and in emissions of various air pollutants (including nitrogen oxides (NOx) and particulate matter (PM)) resulting from the creation of electrified truck lanes on I-710. This alternative was tested for four scenarios corresponding to different percentage of electrified heavy-duty trucks in the I-710 corridor. My results show that creating electrified lanes would slightly reduce congestion in terms of average overall network speed. I also found a substantial reduction in the emissions of several air pollutants by port-related heavy duty trucks, which ranged from 44% to 94% in the scenarios considered. Overall, the reduction in emission possible by the electrification of the freight corridor is a significant improvement but as proposed, the electrification of the I-710 would also create additional traffic problems. This suggests that planning models (such as TransCad) are not sufficient to properly evaluate preliminary designs of freeway changes.
research report
This report describes how a previously proposed logit path flow estimator (LPFE) has been further developed in order to improve the reliability and efficiency of origin-destination (O-D) trip table estimates. The report describes how both steady-state and time-dependent LPFE are implemented in an object-oriented programming (OOP) framework. The performance of the LPFE is tested using synthetic data and the accuracy and reliability of its O-D trip table estimates are quantified. The report also describes the development of Visual PFE and Visual PFE-TD, which are the graphic user interfaces (GUI) for both static and time-dependent LPFE.
