published journal article
Based on the analysis of case studies carried out in seven US cities, attempts to evaluate the potential for expanding the role of private provision of urban commuter bus services. Describes the type and extent of present schemes, the viability of non-subsidized schemes, the issues involved in subsidizing, and finally, assesses the problems and potential of private provision.-R.Land
Phd Dissertation
The activity-based approach to travel demand analysis recognizes that human activities dictate travel. Microsimulation of household activity patterns has gained significant attention as a method for modeling this activity participation. Existing approaches, however, focus on modeling how households solve the activity scheduling problem—how and when each household member should engage in particular activities to meet the needs of the household. This is a top-down approach that recognizes inherent causal links between members of a household but sacrifices modeling flexibility that is necessary for complex policy analysis. This dissertation synthesizes dominant activity analysis theories with concepts from the social simulation and complex systems analysis literature to demonstrate that the motivation and constraints that shape activities are more directly embodied in the activity execution problem—how individuals interact with other entities in their environment to engage in activity. The scheduling problem is re-cast as the adaptive internal process that an individual uses to navigate through this interactive environment to achieve environmentally-derived payoffs. Based on this theory, a microsimulation is described that focuses on the activity execution process. Such a bottom-up approach presents a problem of tractability. This dissertation solves this problem by describing activity execution using a model of negotiated interaction derived from the Contract Net Protocol for distributed computation. This model is shown to be tractable in terms of the number of negotiating individuals, given reasonable limitations on the negotiation process. Then, a complete agent-based model of an urban activity system is described based on this activity execution kernel. This general model is shown to be tractable in terms of the population size, given assumptions on how negotiations are initiated. Finally, results from experiments using candidate adaptive learning algorithms for agents operating in the microsimulation are presented to demonstrate the utility of the microsimulation approach.
published journal article
The international green infrastructure literature has examined rails-to-trails and freeway-to-boulevard conversions, but these strategies can be impractical or politically unfeasible. An understudied movement among United States cities has demonstrated a strategy for greening freeways that remain in service: freeway cap parks, or decks with parks built in the air space directly above below-grade freeway sections that can help reintegrate communities, conceal traffic, reduce air pollution, and provide green space. We provide the first assessment of the design, function, and placement of freeway cap parks and assess the emerging sustainability discourse of cap park planning. We examine 18 completed and 9 proposed cap parks in 24 U.S. cities to identify four cap park development models that can be adapted worldwide to green below-grade freeway segments and reconnect communities. Given historic disparities in freeway placement, we examined the distribution of cap parks and found they are located in areas that could help address disparities in park access in freeways corridors. Our detailed case studies stress the struggle within the cap park sustainability discourse to balance economic, environmental, and equity concerns. Dallas’ Klyde Warren Park is an economic success story, but illustrates how developers use cap parks to sideline equity concerns. Denver’s proposed I-70 cap park illustrates strategies to mitigate environmental justice impacts of freeway expansion projects, but equity concerns remain given continuing impacts of the expanded freeway system. Cap parks should be embraced as a vital component of green infrastructure that reconnects and greens cities divided by freeway construction, but planners should take strong steps to address housing affordability and gentrification concerns for adjacent communities.
research report
The COVID-19 pandemic has had a significant impact on public transit ridership in the United States, especially for rail transit. Land use, development density, and the pedestrian environment are strongly associated with station-level transit ridership. This study examines how these characteristics affect transit ridership pre- and post-COVID and how they differ across station types based on longitudinal data for 242 rail stations belonging to Bay Area Rapid Transit, San Diego Metropolitan Transit System, Sacramento Regional Transit, and LA Metro between 2019 and 2021. We found overall a 72% decrease in station-level ridership, but changes were not uniform. Station areas with a higher number of low-income workers and more retail or entertainment jobs tend to have lower ridership declines, while areas with a large number of high-income workers, high-wage jobs, and higher job accessibility by transit had more ridership losses. When comparing station area ridership and activity changes based on mobile phone user data, ridership declined more drastically than activity across all four rail systems, which implies that rail transit riders switched to other modes of transportation when accessing the station areas. Given these findings, it is likely that rail transit services oriented toward commute travel, especially core station areas with jobs for higher income workers, will continue to have an uneven recovery, posing critical implications for transit resilience planning and equity in the post-pandemic era. Considering sources of funding other than passenger fares to sustain rail transit, strategizing to reinvent and reinforce downtowns as destinations, and shifting rail transit services to appeal to non-commute travel can be promising strategies to support rail transit.
published journal article |
Dec 2025
policy brief |
Sep 2024
working paper
In this essay we offer a view of what economics can say about and learn from urban structure. In doing so, we reach into neighboring disciplines; but we do not aspire to a complete survey even of urban economics, much less of the related fields of urban geography or urban planning. Our focus on internal structure should provide Mayor Daley a more complete basis for comparing Chicago’s density to that of New York, or its degree of centralization to that of Los Angeles. (Throughout this essay we use the word “city,” or the name of a particular city, to mean an entire urban region; other terms with similar meanings are “metropolitan area” and “urban area.”)
working paper |
Sep 1994
Phd Dissertation |
Jun 1996
working paper |
Oct 1995
working paper |
Mar 1997
working paper |
Sep 1998
research report
This project further adapt and enhance the previous research of relevance to event-based Advanced Traveler Information Systems (ATIS) and implement the algorithms for traffic management in Anaheim. This study is also answering some basic questions in ATIS implementation associated with routing strategies, driver’s compliance and network performance. This research develops algorithms for static and dynamic optimal Changeable Message Signs (CMS). The optimized CMS schemes are based on performance evaluations using a traffic simulation-based evaluation model, DYNASMART (Dynamic Network Assignment Simulation Model for Advanced Road Telematics). Performance of ATIS depends on drivers’ compliance behavior, and the compliance issue is addressed in this research. This study develops a framework of driver’s compliance model, and incorporates it into the evaluation framework. The model includes inherent value of guidance system, and the value is analyzed via day-to-day update approach. A limited field test is implemented for the event traffic management. The implementation involves the Caltrans-UCI ATMS research testbed framework at the UCI Institute of Transportation Studies, as well as the physical hardware available for communication to the city of Anaheim. The analytical and heuristic algorithms proposed for use here include those for static and dynamic traffic simulation-assignment. The essential part of algorithmic research is to adapt the network optimization algorithms to generate traffic rerouting plans, which involve aggregation of network paths and their translation to a format usable for changeable message signs existing in Anaheim, as well as other event-based information supply hardware.
working paper |
Jun 1999
published journal article
published journal article
working paper
The following secti-on reviews the development of structure as an organizational variable, discusses the various dimensions of organizational structure in detail, and discusses their application to the transit industry.
published journal article