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Open Access Publications from the University of California

The University of California Transportation Center recognizes that transportation is one component of a societal system that is affected by and has effects on the movement of goods, people, and information. The Center draws on the knowledge of many disciplines, including but not limited to engineering, economics, urban planning, and management in its efforts to support studies that analyze transportation systems and the public policies that are integral to them.

The Center is sponsored by both the United States Department of Transportation (DOT) and the California Department of Transportation (Caltrans). All transportation-related programs within the University of California campuses are eligible for research and educational funding from the Center. The primary campuses involved in UCTC activities are those at Los Angeles, Davis, Irvine, and Berkeley.

UCTC maintains an active program of basic and applied research conducted by University of California faculty and graduate student assistants. The Center supports the University's educational programs in transportation with awards of scholarships and fellowships to students planning careers in transportation. As part of its technology-transfer activities, UCTC sponsors seminars and conferences where scholars and public officials meet to exchange information and research findings. The Center also publishes the results of research it has funded in the form of working papers, reprints of journal articles, and in its official magazine, ACCESS. These publications are distributed widely within the academic, professional, and governmental communities.

Cover page of Dynamic Opportunity-Based Multipurpose Accessibility Indicators in California

Dynamic Opportunity-Based Multipurpose Accessibility Indicators in California

(2012)

Accessibility, defined as the ease (or difficulty) with which activity opportunities can be reached from a given location, can be measured using the cumulative amount of opportunities from an origin within a given amount of travel time. These indicators can be used in regional planning and modeling efforts that aim to integrate land use with travel demand and an attempt should be made to compute at the smallest geographical area. The primary objective of this paper is to illustrate the creation of realistic space-sensitive and time-sensitive fine spatial level accessibility indicators that attempt to track availability of opportunities. These indicators support the development of the Southern California Association of Governments activity-based travel demand forecasting model that aims at a second by-second and parcel-by-parcel modeling and simulation. They also provide the base information for mapping opportunities of access to fifteen different types of industries at different periods during a day. The indicators and their maps are defined for the entire region using largely available data to show the polycentric structure of the region and to illustrate the method as a generator of choice sets in discrete choice models.

Cover page of Walkability Planning in Jakarta

Walkability Planning in Jakarta

(2011)

Walking is the main mode of transportation for many of the world’s people, particularly those in cities of the majority world. In the metropolitan region of Jakarta, walking in the public realm constitutes the main transportation mode for almost 40 percent of trips—a massive contribution to urban mobility. On the other hand, there is no comprehensive planning for pedestrians in an analogous manner to other modes of transportation. Pedestrian facilities are often dilapidated, damaged, dangerous, or missing completely. Additionally, there is no process for assessing the inventory of pedestrian facilities, planning pedestrian facilities at a region-wide level, or even identifying the location of vernacular pedestrian routes in low-income and informal areas. Provincial pedestrian planning focuses on piecemeal, symbolic spaces such as monumental plazas that serve the nation-building project, but overlooks the functional network of routes that address the daily needs of the city’s residents.

This dissertation examines the issue of walkability planning in Jakarta by investigating what matters to pedestrians and how pedestrian space is produced. The research employs mixed methods, including pedestrian network groundtruthing, structured streetscape observations, multimodal traffic counts, pedestrian activity mapping, pedestrian surveys and interviews with policy-makers. Data is analyzed through a combination of in-depth qualitative analysis as well as quantitative and statistical analysis.

Based on this research, six key elements of walkability planning are proposed for Jakarta: multidisciplinarity, ethnography, accessibility, legibility, integrated activity, and shared streets.

A literature review of walkability metrics reveals that walking is a highly multidisciplinary activity, with very different metrics emerging from different fields. In order to effectively encourage pedestrian activity, new multidisciplinary metrics should integrate the perspectives of all of these related disciplines and pedestrian planning should occur through inter-agency coordination. In Jakarta, interviews with policy-makers suggested that pedestrian planning is hindered by the fact that there is no lead agency for pedestrian planning, and there is a lack of cooperation between the different agencies that plan and produce urban public space. Pedestrian planning is also hindered by a discursive framework that is both modally and geographically biased—favoring motorized, long-distance modes of transportation and employing method derived from a Western research and planning norms.

In order to overcome this discursive bias, ethnography should become a standard part of urban research, planning and design. The need for ethnography and qualitative analysis was made visible by the mismatch between standard transportation terminology, and prevailing practices observed in pedestrian mapping exercises and raised by pedestrians in on-the street interviews. For example, standard survey categories do not account for informal or integrated activity patterns like mobile street vending. From surveys conducted with mobile street vendors, it was difficult to separate their pedestrian activities into categories of travel from home to work, business-related travel, and visiting friends and relatives. In fact, it was difficult to even separate their travel from their activities since many vendors carried out business as they made their way through the neighborhood. With a large portion of the population engaged in the informal sector, the discrepancy between assumed and actual behavior severely compromises the quality of transportation-related research that is conducted in Jakarta and many other majority world cities. Ethnographic and qualitative research methods may therefore assist in producing more context-sensitive planning data and outcomes. These context-sensitive methods could include new analytical methods that focus on integrated activity, rather than trip-based or activity-based analysis.

In relation to pedestrian activity, context-sensitive planning encompasses new approaches to accessibility that combine the notion of transportation accessibility with disabled access and universal access standards. The need for such an approach was revealed during interviews with policy-makers, who described accessibility in terms of market goods rather than human rights. Within the market for urban public space, ordinary pedestrians were unable to compete with other modes of transportation; within the market for urban impressions, ordinary pedestrian spaces were outcompeted by prominent, symbolic spaces; and within the market for cultural capital, ordinary pedestrians were excluded from planning processes because even the discourse of pedestrian planning was inaccessible to regular residents. In response to this problem of exclusion, integrated accessibility may facilitate inclusion in both planning processes and urban spaces within the city. In particular, integrated accessibility would aim to provide comprehensive routes of travel for all pedestrians, rather than isolated pockets of so-called accessible (yet unreachable) facilities.

More context sensitive planning would also be facilitated through greater legibility of fine-grained and vernacular pedestrian networks that were missing from standard planning maps. These fine-grained networks represent highly connected facilities that serve much of Jakarta’s pedestrian transportation task. While the current synoptic illegibility of these areas may conveniently allow some communities to avoid state intrusion, it also means that low-income populations are chronically under-served with respect to basic urban planning and services. Increased legibility therefore allows for improvement and maintenance of urban systems like safe, functional pedestrian networks, and it may also play a role in increasing tenure security for Jakarta’s significant floating population.

In many of these vernacular spaces, new street design approaches would also benefit pedestrians, who tend to use the streets as shared spaces, rather than spaces that are rigidly segregated by mode. Pedestrian activity mapping revealed that only an overwhelming majority of pedestrians used streets as hybrid spaces, with activity types falling into the categories of surface sensitive, risk-averse, distance-minimizing and stationary pedestrians. More realistic shared street designs would therefore accommodate —rather than ignore—the types of activities that occur along Jakartan streets. Design standards for “great streets” in Jakarta would also emphasize the safe sharing of streets through self-enforcing approaches to speed limits, and the integration of various urban elements like drainage, mobility and public-private interaction.

While walkability planning in Jakarta displays many “wicked problem” features, there is much that can be done to improve, if not resolve, conditions for pedestrians within the region. Recommended strategies for walkability planning in Jakarta include a regional walkability plan and environmental policy developed using participatory planning, reformed governance and institutional arrangements, and a constituency building approach. The strategies also include expansion of road designations and an integrated accessibility strategy that draws upon new data sources from a WikiPlaces network map, an integrated activity study and pedestrian network cost-benefit analysis. In addition to Jakarta specific proposals, a number of proposals are made to advance discourse on walkability more generally. These approaches include decentered analysis of integrated activity, informal economic activity analysis, vernacular placemaking and Asian shared street design.

Pedestrians and pedestrian plans traverse diverse physical, administrative and disciplinary spaces in cities of the world. Integrated and multidisciplinary approaches are therefore required to understand and accommodate these key users of public space. In Jakarta, walkability planning has potential to improve urban transportation efficiency while contributing to traffic safety, economic vitality, environmental quality and democratic governance. Successful walkability planning in Jakarta may also provide a model for planning in other cities where Western models of planning are unrealistic, inequitable and inappropriate. Jakartan lessons on walkability planning are particularly relevant, and improvements in walkability are particularly powerful, for cities characterized by relatively low median incomes, high land use densities, a substantial informal sector, rapid urbanization and rapid motorization. By improving walkability planning in Jakarta and other cities of the majority world, policy-makers and planners can move toward more sustainable, socially equitable and efficient cities.

Cover page of Understanding Places Using a Mixed Method Approach

Understanding Places Using a Mixed Method Approach

(2011)

With the increased application of the activity based approach comes the inherent need to incorporate more detail regarding behavior. This need for detail has in turn created a need for both a deeper understanding and theoretical basis for behavior, and the incorporation of data collection and analysis methods to handle more behavioral detail. Because of this, the use of qualitative and mixed method approaches in travel behavior has received increased attention over the last few decades. In this paper, quantitative and qualitative methodologies are discussed and applied to data collected in Santa Barbara, California, measuring peoples’ attitudes about places (sense of place). Both quantitative and qualitative methods are applied using first a factor analysis and complementing this with a qualitative analysis of text from an open-ended question. The findings of these analyses are compared and incorporated to contribute to a greater understanding of both sense of place and behavior. Theoretical developments and implications for future research are discussed in light of analysis findings.

Cover page of Using Sense of Place to Model Behavioral Choices

Using Sense of Place to Model Behavioral Choices

(2011)

With the introduction and increasing reliance on the activity based approach in travel demand analysis and forecasting, discrete choice methods are more often in spatial contexts (e.g., residential location, job location, destination/activity choice). A necessity in specifying spatial choice models is the inclusion of the alternatives decision makers consider, and a realistic inclusion in the specification of the attributes of these alternatives, the characteristics of the decision making context, and the relevant characteristics of the decision maker. These details describe differences that exist among choices and individuals making choices. In the case of travel behavior, attributes of the alternatives have traditionally included attributes such as cost, distance, time, level of service and opportunities. Researchers however have recognized the benefit of attitudes in the estimation of choice models, showing improvement in explanatory power with the inclusion of attitudinal attributes of the individual. There is still however a vast expanse of unexplored attitudinal attributes in choice modeling. Particularly lacking in choice modeling is a strong theoretical underpinning of attitude formation and attitude relation to choice. Theorists in geography in the mid to late 1970s recognized and developed one such theory regarding the emotional and attitudinal association that people have with places. This became known as the theory of sense of place, which is the “affective ties with the material environment” (Tuan, 1974). This theory presents great potential in furthering the descriptive power of choice models, particularly destination choice. However, challenges abound, as this theory is rich in development, but poor in computational operationalization. In addition, everyday activity locations have not been adequately explored in sense of place quantification. In this paper, an overview of developments in discrete choice methods is presented, followed by a discussion of sense of place. Current and future work is discussed and benefits to choice modeling are presented.

Cover page of The Half-Mile Circle: Does It Best Represent Transit Station Catchments?

The Half-Mile Circle: Does It Best Represent Transit Station Catchments?

(2011)

One-half mile has become the accepted distance for gauging a transit station’s catchment area in the U.S. It is the de facto standard for planning TODs (transit oriented developments) in America. Planners and researchers use transit catchment areas not only to make predictions about transit ridership and the land use and socioeconomic impacts of transit, but also to prescribe regulations, such as the relaxation of restrictive zoning, or carve out TOD financial plans. This radius is loosely based on the distance that people are willing to walk to transit, but this same reasoning has been used to justify other transit catchment areas. Using station-level variables from 1,449 high-capacity American transit stations in 21 cities, we aim to identify whether there is clear benchmark between distance and ridership that provides a norm for station-area planning and prediction. For the purposes of predicting station-level transit ridership, we find that different catchment areas have little influence on a model’s predictive power. This suggests that transit agencies should use the easiest and most readily available data when estimating direct demand models. For prescribing land-use policy, by contrast, the evidence is less clear. Nevertheless, we find some support for using a quarter-mile catchment area for jobs around transit and a half-mile catchment for population. While these distances will likely vary from place to place and depending on the study purpose, they are a good starting point for considering transit-oriented policy or collecting labor-intensive data, such as surveys, about transit-adjacent firms or households.

Cover page of The Half-Mile Circle: Does It Represent Transit Station Catchments?

The Half-Mile Circle: Does It Represent Transit Station Catchments?

(2011)

One-half mile has become the accepted distance for gauging a transit station’s catchment area in the U.S. It is the de facto standard for planning TODs (transit oriented developments) in America. Planners and researchers use transit catchment areas not only to make predictions about transit ridership and the land use and socioeconomic impacts of transit, but also to prescribe regulations, such as the relaxation of restrictive zoning, or carve out TOD financial plans. This radius is loosely based on the distance that people are willing to walk to transit, but this same reasoning has been used to justify other transit catchment areas. Using station-level variables from 1,449 high-capacity American transit stations in 21 cities, we aim to identify whether there is clear benchmark between distance and ridership that provides a norm for station-area planning and prediction. For the purposes of predicting station-level transit ridership, we find that different catchment areas have little influence on a model’s predictive power. This suggests that transit agencies should use the easiest and most readily available data when estimating direct demand models. For prescribing land-use policy, by contrast, the evidence is less clear. Nevertheless, we find some support for using a quarter-mile catchment area for jobs around transit and a half-mile catchment for population. While these distances will likely vary from place to place and depending on the study purpose, they are a good starting point for considering transit-oriented policy or collecting labor-intensive data, such as surveys, about transit-adjacent firms or households.

Cover page of The Quantified Traveler: Using personal travel data to promote sustainable transport behavior

The Quantified Traveler: Using personal travel data to promote sustainable transport behavior

(2011)

With the advent of ubiquitous mobile sensing and self-tracking groups, travel demand researchers have a unique opportunity to combine these two developments to improve the state of the art of travel diary collection. While the use of mobile phones and the inference of travel diaries from GPS and sensor data allows for lower-cost, longer surveys, we show how the self-tracking movement can be leveraged to interest people in participating over a longer period of time. By compiling personalized feedback and statistics on participants’ travel habits during the survey, we can provide the participants with direct value in exchange for their data collection effort. Moreover, the feedback can be used to provide statistics that influence people’s awareness of the footprint of their transportation choices and their attitudes, with the goal of moving them toward more sustainable transportation behavior.

We describe an experiment that we conducted with a small sample in which this approach was implemented. The participants allowed us to track their travel behavior over the course of two weeks, and they were given access to a website they were presented with their trip history, statistics and peer comparisons. By means of an attitudinal survey that we asked the participants to fill out before and after the tracking period, we determined that this led to a measurable change in people’s awareness of their transportation footprint and to a positive shift in their attitudes toward sustainable transportation.

Cover page of Reliable GPS Integer Ambiguity Resolution

Reliable GPS Integer Ambiguity Resolution

(2011)

To operate, guide and control vehicles in low visibility conditions, it is critical that the states of the vehicle are accurately estimated, which includes the three dimensional position, velocity, and attitude. This can be accomplished by GPS (Global Positioning System) aided encoder or GPS aided inertial approaches. The overall positioning accuracy of either approach will be determined by the GPS performance. Real-time centimeter accuracy GPS positioning can be achieved using carrier phase measurements. This requires fast and reliable on-the-°y integer ambiguity resolution.

In this dissertation, we focus on resolving GPS ambiguity problem, including both integer ambiguity estimation and integer ambiguity validation. For integer ambiguity estimation, a brief overview of previous work on integer ambiguity resolution is first presented. Then, an improved integer ambiguity resolution method is proposed. Subsequently, simulations and real-world data are presented to demonstrate the effectiveness of the method. We also present integer ambiguity algorithms with auxiliary measurements and algorithms with multiple epoch measurements, both of which are useful in GPS challenging areas. For integer ambiguity validation, a brief overview is first presented, and then analytic discussion and test results on several popular validations methods are studied. Finally we discuss GPS modernization and its effect on integer estimation and validation.

Cover page of Forecasting with Dynamic Microsimulation: Design, Implementation, and Demonstration

Forecasting with Dynamic Microsimulation: Design, Implementation, and Demonstration

(2011)

In this project we develop a new travel demand forecasting system that integrates demographic microsimulation with urban simulation and travel demand model systems. Our research objective is to identify the barriers in integrating complex simulation models and eliminate them by offering a demonstration of problems and solutions. The basic ingredients of this new model system are: a) a dynamic demographic simulator designed and tested with repeated observations of the same individuals in another context that will be transferred to a case study in Santa Barbara, CA; b) a modified version of the recently finalized Urbansim model that will also be calibrated with data from Santa Barbara, CA; and c) travel demand models that account for intrahousehold interactions and path based accessibility that were estimated with data from California. The model system is unique because it combines within a day and across years human behavior dynamics and it will push the frontier of modeling and simulation one step further. A demonstration of a pilot test is offered using data from Santa Barbara, CA.

Cover page of Collaboration Is Not Enough: Virtuous Cycles of Reform in Transportation Policy

Collaboration Is Not Enough: Virtuous Cycles of Reform in Transportation Policy

(2011)

Over the past two decades, a burgeoning literature has touted the promise of regional collaboration to address a wide range of issues. This article challenges the premise that horizontal collaboration alone can empower regional decision- making venues. By analyzing efforts to create regional venues for transportation policy making in Chicago and Los Angeles, the authors show that vertical power is essential to building regional capacities. Only by exercising power at multiple levels of the political system can local reformers launch a virtuous cycle of reform that begins to build enduring regional capacities.