Nebiyou Tilahun

A Moment of Time: Reliability in Route Choice Using Stated Preference

Understanding how reliability is valued is important because it provides insight into how aims of policies that aspire to provide better transport options can be more fully integrated with user expectations. Better reliability is a desired outcome of transportation policies because it reduces scheduling costs. This study uses a stated preference survey to collect route preference data, in which each route is described by the travel time experience on it. Because travel-time decisions are made from momentary recollections of past experience, the paradigm adopted in this study is that the mode travel time rather than the mean is the important basis for travel time decisions. The authors then explore three alternate measures of reliability and use them to estimate route choice models on the basis of the stated preference data. Two of the measures, range coupled with lateness probability and standard deviation, have been explored before. A third measure based on time moment (moments of inertia) measured from the mode travel time is also proposed and tested. Each measure reveals something different about how people value different aspects of reliability. In all cases, reliability is valued highly, although differently depending on how it is defined. The values of reliability and travel time highlight that transportation policy makers can provide significant benefits to users from strategies that seek to increase reliability.

Big Data and Urban Informatics: Innovations and Challenges to Urban Planning and Knowledge Discovery

Big Data is the term being used to describe a wide spectrum of observational or “naturally-occurring” data generated through transactional, operational, planning and social activities that are not specifically designed for research. Due to the structure and access conditions associated with such data, their use for research and analysis becomes significantly complicated. New sources of Big Data are rapidly emerging as a result of technological, institutional, social, and business innovations. The objective of this background paper is to describe emerging sources of Big Data, their use in urban research, and the challenges that arise with their use. To a certain extent, Big Data in the urban context has become narrowly associated with sensor (e.g., Internet of Things) or socially generated (e.g., social media or citizen science) data. However, there are many other sources of observational data that are meaningful to different groups of urban researchers and user communities. Examples include privately held transactions data, confidential administrative micro-data, data from arts and humanities collections, and hybrid data consisting of synthetic or linked data.

Contacts and Meetings: Location, Duration and Distance Traveled

The role of contacts on travel behavior has been getting increasing attention. This paper reports on data collected on individuals social meetings and the choice of in-home/out-of-home meeting locations as well as the distance traveled and duration of out-home-meetings and its relationship to the type of contact met and other attributes of the meeting. Empirically we show that in-home meetings tend to occur most often with close contacts and less often with distant contacts. The purpose, meeting day, and household size suggest that leisure, weekend and large household size people tend to have their meetings either at their home or at their contacts home. In addition when meetings occur outside of the house, the duration is longer for close contacts and distance to the meeting location is directly influenced by duration and indirectly by the relationship type. Overall the paper illustrates that relationship type along with other meeting specific and demographic variables is important in explaining the location, duration and distance traveled for social meetings.

Integrated and Continuing Transportation Services for Seniors: Case Studies of New Freedom Program

The aging of the American population has raised a number of concerns about senior mobility. The New Freedom (NF) program, which was designed to go above and beyond the transportation requirements of the Americans with Disabilities Act, has been used to fund transportation for seniors. The primary purpose of this paper is to present the results of an exploratory analysis of the social, physical, and functional health and mobility outcomes experienced by seniors who are clients of NF services and the associated Coordinated Human Services Transportation Plan (CHSTP) processes. The paper uses data from primary surveys of the following groups from seven urban, suburban, and rural locations: (a) NF-funded transportation service users, (b) program managers operating the services, and (c) locally selected lead and partner organizations involved in developing the CHSTPs. Results show that concerns about senior mobility vary significantly by a number of functional, social, and physical disability indicators, including instrumental activities of daily living. These indicators are substantially more complex than a chronological accounting of age. A principal component analysis yielded two constructs underlying seniors’ mobility: a transportation deprivation component and an independence and health deprivation component. Each component has implications for different types of services. To the extent that the NF program has supported transportation services that are supplemental to integrated care for seniors and thereby enable a continuum of care, the program has enhanced community-based interventions to meet the complex mobility needs of seniors in the seven locations.

Walking access to transit stations: evaluating barriers with stated preference

The last-mile problem refers to challenges that travelers experience in accessing transit stations from their activity locations. The objective of this study was to find the contributing factors that reduced peoples propensity to walk and take transit. A stated preference study was conducted in the Chicago, Illinois, area with an online survey composed of questions based on the actual travel experience of the respondents. The data were used to estimate a logit choice model. The findings showed that access time, safety from crime, and sidewalk availability were important factors that influenced peoples choice to walk to transit. The model was used to estimate time-based values associated with reduction in crime and sidewalk availability. The study also estimated the propensity to walk and use transit for a representative resident in each tract of the Chicago metropolitan area. These values were then used to identify census tracts where acute to minimal barriers to walking to transit existed. In addition to suburban areas that were not well suited for walking to transit, the results identified areas that were well served by transit but had other barriers that inhibited walking access to transit.

Seeing Cities Through Big Data

This book introduces the latest thinking on the use of Big Data in the context of urban systems, including research and insights on human behavior, urban dynamics, resource use, sustainability and spatial disparities, where it promises improved planning, management and governance in the urban sectors (e.g., transportation, energy, smart cities, crime, housing, urban and regional economies, public health, public engagement, urban governance and political systems), as well as Big Datas utility in decision-making, and development of indicators to monitor economic and social activity, and for urban sustainability, transparency, livability, social inclusion, place-making, accessibility and resilience.

Introduction to Seeing Cities Through Big Data: Research, Methods and Applications in Urban Informatics

The chapters in this book were first presented in a 2-day workshop on Big Data and Urban Informatics held at the University of Illinois at Chicago in 2014. The workshop, sponsored by the National Science Foundation, brought together approximately 150 educators, practitioners and students from 91 different institutions in 11 countries. Participants represented a variety of academic disciplines including Urban Planning, Computer Science, Civil Engineering, Economics, Statistics, and Geography and provided a unique opportunity for discussions by urban social scientists and data scientists interested in the use of Big Data to address urban challenges. The papers in this volume are a selected subset of those presented at the workshop and have gone through a peer-review process.

Understanding Transportation Accessibility of Metropolitan Chicago Through Interactive Visualization

Accessibility is an important element in urban transportation planning. Accessibility measures combine mobility and land use measures to provide a more complete picture of the transportation-land use nexus than either of these measures alone. By providing insights into the varying degrees to which different areas of a region are connected to opportunities by the transportation system, accessibility analysis helps urban planners to understand the relationship between transportation and land use, and provides reference for them to improve the equality of the residents. Calculating accurate accessibility values and visualizing them in an efficient way is a complex and challenging process. In this paper, we present a web-based system that visualizes multimodal accessibility to multiple land uses of Chicago metropolitan area, as the first step of an effort to build an integrated platform for accessibility analysis tasks. We also discuss some use cases of this system, and show its effectiveness by providing experts feedback of this prototype.

Time Use, Disability, and Mobility of Older Americans

This study explored how disability, mobility, social and leisure engagement, and travel behavior influence older people’s life satisfaction. The study used the 2013 Disability and Use of Time data for people ages 50 years and older, many of whom reported physical impairments. The study developed a model that related life satisfaction with various time use, disability, and mobility variables. Summary statistics of time use showed that as people aged, they spent more time on solitary, passive leisure activities; social face-to-face time did not seem to change very much. Alone passive leisure time use was especially large for those who experienced a physical mobility-related disability and were carless. The study used an ordinal logistic regression and found that longer alone leisure time uses were associated with lower life satisfaction. Life satisfaction was positively affected by transportation variables, such as vehicle availability. The study also found that social face-to-face time use had a weak positive relationship with life satisfaction, and technology-mediated social activities had a strong negative relationship with life satisfaction.

An Agent-Based Model of Worker and Job Matching

This paper proposes and tests an agent-based model of worker and job matching. The model takes residential locations of workers and the locations of employers as exogenous and deals specifically with the interactions between firms and workers in creating a job-worker match and the commute outcomes. It is meant to illustrate that by explicitly modeling the search process and the interactions between firms and individuals, origins and destinations (ODs) can be linked at a disaggregate level that is reasonably true to the actual process. The model is tested on a toy-city and the using Twin Cities are. The toy-city model illustrated that the model leads to reasonable outcomes, with agents selecting the closest work place when wage and skill differentiation is absent. Relaxing these assumptions increases the observed commute. Especially the introduction of wage dispersion in the model increases the the average home to work distance significantly. Using data from Minnesota, the results on aggregate are shown to capture the trends in the observed data, and illustrate that the behavior rules as implemented lead to reasonable patterns. The results and potential future directions are also discussed.