published journal article
Phd Dissertation
Within the existing body of activity scheduling behavior models, the Household Activity Pattern Problem (HAPP) model is an activity-based model characterized by a rigorous mathematical programming formulation. The HAPP model can deal with detailed activity patterns including spatial, temporal, personal and modal information with complex constraints. The HAPP model is in the form of a Mixed Integer Programming model (MIP) which includes both continuous variables and discrete variables. Such temporal attributes of an activity pattern as starting time, duration and ending time are continuous variables, and those spatial attributes associated with the sequencing of activities, travel modes, participation persons and vehicles are discrete variables. As formulated, the HAPP model is a constrained utility maximizing model. Empirical application of the model to a demand context involves estimation of the components of the objective function, based on data from observed patterns. However, due to computational difficulties in HAPP model, Genetic Algorithms (GA) have been proposed to estimate the set of factors influencing the objective function that “best” reproduces the observed spatial and temporal interrelationships. The fitness score in the GA approach used to evaluate the quality of the representation is the difference between the Observed Activity Pattern Scheduling (OAFS) and Predicted Activity Pattern Scheduling (PAPS), or the similarity between the two. In this dissertation, we propose a new similarity metric for the GA estimation procedure. The metric considers the problem based on the continuous representation of discrete activity variables along the temporal dimension. Three similarity judging rules work together to form the similarity definition of similarity metric. They are: the temporal overlap among activities of different type, correspondence between participant person and vehicle used for each activity; permutations in the temporal sequence of activities and activity duration length similarity. The estimation procedure is tested on data drawn from a well-know activity/travel survey.
conference paper
published journal article
published journal article
working paper
Some road-pricing demonstrations use an approach called “value pricing”, in which travelers can choose between a free but congested roadway and a priced roadway. Recent research has uncovered a potentially serious problem for such demonstrations: in certain models, second-best tolls are far lower than those typically charged, and the welfare gains from profit maximization are small or even negative. That research, however, assumes that all travelers are identical and it therefore neglects the benefits of product differentiation, by which people with different values of time can choose a suitable cost/quality combination. Using a model with two user groups, we find that accounting for heterogeneity in value of time is important in evaluating constrained policies, and improves the relative performance of policies that offer differential prices. Nevertheless, for most of the reasonable range of heterogeneity, second-best pricing produces far fewer benefits than pricing both roadways optimally, and profit-maximizing tolls are so high that overall welfare is reduced from the no-toll baseline.
working paper
Policy issues obstruct use of advanced traffic management technology in Southern California. Reliable equipment for electronic road pricing (ERP) is available that could establish a regionwide network of high occupancy vehicle (HOV) facilities where single occupant users (SOV) buy access. Private toll roads plan to use automatic vehicle identification (AVI), automatic toll collection (ATC), and changeable message signs to guide traffic into high-occupancy, buy-in lanes. Public agencies oppose expansion o this technology to the regional HOV network. Some hypothesize that the high-occupancy, toll (HOT) lanes would not promote ridesharing and related air quality objectives. This paper tests this hypothesis by applying a multinomial logit model to potential travel in one freeway corridor where private, buy-in lames are under construction. The hypothesis is not supported; free HOV lanes can be converted to HOT lanes using advanced technology to achieve an increase in average vehicle occupancy (AVO). The effect on congestion is uncertain.
working paper |
Dec 1994
working paper |
Sep 1994
working paper |
Oct 1993
working paper |
Jan 1997
book/book chapter |
Oct 1998
published journal article
This paper relies on a unique dataset collected during a national survey of US households to explore how different sources of information (print, television, radio, family/friends, work/school and others) influence the decision to start recycling. Although print media are influential, it is found that face-to-face communication (through family/friends or work/school) is the most effective medium to get people to start recycling. However, it is even better to provide households with recycling information from multiple sources. The respondents in this study identify concerns about storage space, time and the safety of recycling as the main obstacles to start recycling. In addition, age and ethnicity are statistically significant but not income or education. These findings should be useful for crafting information campaigns designed to boost recycling, although to be successful these campaigns need to incorporate findings from environmental psychology and knowledge of specific communities.
conference paper
conference paper
Demands for long haul freight movements continue to grow due primarily to increasing international trade. This increase drives the need for major infrastructure improvements at the local, state and federal level. Although long haul freight mostly moves on the high mobility network of the interstate highway system, local road networks play an important role in providing efficient access to the high mobility network. This study applies a bi-level network design approach to solve the integrated network design problem. Network representations, the upper level and lower level problems, are adjusted to as appropriate for a freight network study. Our study presents a framework for integrated network improvement project selection. The study output can be used as supplemental information to traditional transportation planning tools such as benefit-cost analysis.
