P. Christopher Zegras

Future Mobility Survey

The Future Mobility Survey (FMS) is a smartphone-based prompted-recall travel survey that aims to support data collection initiatives for transport-modeling purposes. This paper details the considerations that have gone into the surveys development, including the smartphone apps for iPhone and Android platforms, the online activity diary and user interface, and the background intelligence for processing collected data into activity locations and travel traces. The various trade-offs concerning user comprehension, resource use, and participant burden, including findings from usability tests and a pilot study, are discussed. Close attention should be paid to the simplicity of the user interaction, determinations of activity locations (such as the false positive and false negative trade-off in their automatic classification), and the clarity of interactions in the activity diary. The FMS system design and implementation provide pragmatic, useful insights into the development of similar platforms and approaches for travel and activity surveys.

Transportation activity analysis using smartphones

Transportation activity surveys investigate when, where and how people travel in urban areas to provide information necessary for urban transportation planning. In Singapore, the Land Transport Authority (LTA) carries out such a survey amongst households every four years. The survey is conducted through conventional questionnaires and travel diaries. However, the conventional surveys are problematic and error-prone. We are developing a smartphone-based transportation activity survey system to replace the traditional household surveys, which can potentially be used by LTA in future.

INFLUENCE OF LAND USE ON TRAVEL BEHAVIOR IN SANTIAGO, CHILE

In an attempt to expand the research base on the land use-transport link in the developing world, a microeconomic model developed in the industrialized world context is adopted. The analysis focuses on the influence of three gross measures of urban form on travel behavior in Santiago, Chile. Controlling for socioeconomic and demographic factors, the analysis attempts to demonstrate the influence of population density, relative share of commercial and service land uses, and relative share of vacant land on an individuals propensity to make home-based, nonwork, non-school (HB NWNS) walking trips. Consistent with intuition, the model results suggest that the relative share of land devoted to commercial and service uses in the zone of trip origin increases the likelihood of making HB NWNS walking trips, whereas the relative share of vacant land decreases the probability. Somewhat surprisingly, population density in the zone of origin has no significant effect.

Exploratory Analysis of a Smartphone-Based Travel Survey in Singapore

Future Mobility Sensing (FMS) is an innovative smartphone-based travel survey that was field-tested in 2012 and 2013, together with the Household Interview Travel Survey (HITS), in Singapore. This paper presents the findings of an exploratory analysis of the data collected in this test. The clustering of the day patterns from the FMS data revealed a large day-to-day variability of user behavior that could not be captured by a snapshot with a 1-day survey. Even the high cross-sectional variability from the larger sample size of a traditional survey would not have achieved the comprehensive set of heterogeneous patterns provided by FMS. Some common problems in traditional surveys—such as the underreporting of trips, the overestimation of travel times, and the inaccuracy of locations and times—can apparently be reduced by FMS. The FMS data have higher resolution and better accuracy compared with the HITS data. In addition, FMS is well suited to the collection of multiday data because additional costs are marginal and the user burden decreases over time. FMS offers a promising technology for the next generation of travel data collection.

Household Income, Travel Behavior, Location, and Accessibility: Sketches from Two Different Developing Contexts

This paper analyzes the differences in travel behavior and location characteristics across different income groups in two cities in different parts of the world: Chile and China. Vehicle ownership rates, mode choices, trip rates and purposes, and travel times and distances are compared according to high-, middle-, and low-income terciles in Chengdu, China, and Santiago, Chile, with the use of recent household travel surveys. Household location characteristics are also compared, and different measures of accessibility are presented. Results suggest commonalities and differences and build a foundation on which future analytical models can be developed and more rigorous and comparable accessibility measures might be derived.

Taxicabs as Public Transportation in Boston, Massachusetts

In many American cities, the taxicab is an important but frequently overlooked public transportation mode and represents a significant opportunity to provide mobility in many places where conventional mass transit cannot do so cost-effectively. This paper investigates the taxicab and its role as a form of public transportation and uses the taxicab system in Boston, Massachusetts, to study the modes function in the city as well as its relationship to other forms of transportation. The central inquiry of this paper is when and where the taxicab operates as a complement or a substitute to Bostons mass transit system and which factors appear to affect its fulfillment of each role. Taxicab activity in Boston is analyzed with trip-level data recorded for Boston taxicabs during the past 2 years, mapping of taxicab activity, and specification of regression models that illuminate significant relationships between the taxicab, transit access, and other characteristics of the urban environment. Evidence suggests that the taxicab acts as both a mass transit substitute and complement in Boston and that this tendency varies by transit line and time of day. These models are also used to infer the existence of unmet demand for taxicab service.

By Community or Design? Age-restricted Neighbourhoods, Physical Design and Baby Boomers’ Local Travel Behaviour in Suburban Boston, US

This article analyses the travel behaviour, residential choices and related preferences of 55+ baby boomers in suburban Boston, USA, looking specifically at age-restricted neighbourhoods. For this highly auto-dependent group, do neighbourhood-related characteristics influence local-level recreational walk/bike and social activity trip-making? The analysis aims to discern community (for example, social network) versus physical (for example, street network) influences. Structural equation models, incorporating attitudes and residential choice, are used to control for self-selection and to account for direct and indirect effects among exogenous and endogenous variables. The analysis reveals modest neighbourhood effects. Living in age-restricted, as opposed to unrestricted, suburban neighbourhoods modestly increases the likelihood of residents being active (i.e. making at least one local recreational walk/bike trip) and the number of local social trips. Overall, the age-restricted community status has greater influence on recreational and social activity trip-making than the neighbourhood physical characteristics, although some community–neighbourhood interaction exists.

Dynamics of Automobile Ownership Under Rapid Growth

Little research has focused on how the factors that influence travel behavior change in rapidly developing and increasingly motorized cities. This paper examines household motor vehicle ownership and focuses on potential variations in the preferences revealed through vehicle choice models estimated for Santiago, Chile, in 1991 and 2001 and includes measures of relative location, subway proximity, residential density, and land use mix. The results indicate that preferences changed between 1991 and 2001 and suggest that as incomes rise and vehicle ownership becomes increasingly affordable, the apparent influence of demographic, land use, and other contextual variables changes. The results vary across land use and locational variables; most notably, the relationship between vehicle ownership and land use mix appears to weaken over time, whereas the effect of the distance to the central business district strengthens, and the effect of residential density varies in the apparent direction of change, depending on the vehicle ownership category. By 2001, proximity to the subway had an apparent effect on the household decision to own three or more vehicles. This research shows that although income and motorization rates rapidly increased in Santiago, certain elements of the built environment influenced household vehicle ownership, and these influences changed over time. Future research should focus on potential market segments, such as suburban versus urban; aim to control for self-selection regarding land use and locational characteristics; and better understand the implications for travel forecasting.

Shifting Urban Priorities?: Removal of Inner City Freeways in the United States

Much of the original Interstate infrastructure built in the 1950s and 1960s in the United States is approaching or has already reached the end of its useful life, and now requires large investments for rehabilitation. At the same time the freeway revolt has evolved into a more widespread movement, underlined by values such as sustainability. The vigorous debate about the future of urban highways and mobility continues with the development of a fairly recent phenomenon: urban freeway removal. This paper works toward a theory of highway removal by examining three different cases in which urban freeway removal was a seriously considered option—two in which the freeway was removed and replaced with a lower-capacity at-grade boulevard and one in which the freeway ultimately was not removed. The analysis suggests that freeway removal will take place only when (a) the freeways condition raises concerns about its integrity and safety; (b) a window of opportunity exists, some event that enables a freeway removal alternative to gain serious consideration; (c) the value of mobility is lower than other objectives such as economic development; and (d) those in power value other benefits more than they value the benefits associated with freeway infrastructure.

The Kyoto Protocol and Sustainable Cities: Potential Use of Clean-Development Mechanism in Structuring Cities for Carbon-Efficient Transportation

This paper assesses the possibility for changing urban development patterns to reduce transportation greenhouse gas (GHG) emissions. The analysis was carried out as part of a larger project exploring the possibility of using the clean development mechanism (CDM) to reduce transportation GHG emissions in Santiago, Chile. The paper provides an overview of the analytical approach, which includes an integrated travel demand model with sensitivity to mesolevel land use variations, a method to generate optimal land use scenarios that relate to emission reductions, and a process to estimate the level of subsidies needed to produce those land use scenarios. Limitations to the approach and suggestions for future research are discussed. The paper concludes with an assessment of the results in the face of the fairly strict requirements for project development and implementation implied by the CDM.