working paper

The Built Environment and Physical Activity: Empirical Methods and Data Resource

Publication Date

October 31, 2003

Author(s)

Marlon Boarnet

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

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Abstract

Does a person’s environment influence their physical activity? Intuition, theory, and preliminary evidence all suggest that there is an association between environment and physical activity, but questions of causality and magnitude remain poorly answered, in large part due to data challenges. If public health policy is to make meaningful links to the built environment, the literature will require careful tests of causal links and an understanding of the magnitude of those links. This paper reviews the data that are available for testing hypotheses about the built environment, physical activity, and health outcomes, both to educate the research community about existing data and current challenges and to illuminate data gaps that should be addressed as this research agenda moves forward.

Phd Dissertation

Assessment of a self-organizing distributed traffic information system : modeling and simulation

Publication Date

September 15, 2003

Author(s)

Xu Yang

Areas of Expertise

Intelligent Transportation Systems, Emerging Technologies, & Big Data

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working paper

The Impacts of Motor Vehicle Operation on Water Quality: A Preliminary Assessment

Publication Date

August 31, 2003

Author(s)

Hilary Nixon, Jean-Daniel Saphores

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Zero-Emission Vehicles & Low-Carbon Fuels

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Abstract

Environmental studies of motor vehicles typically focus on air pollution or noise, but ignore water pollution. In this paper, we examine some of the impacts of motor vehicle transportation on non-point source and on groundwater pollution. Our estimates of the present value of costs for cleaning up leaking underground storage tanks and for controlling highway runoff for major arterials range from $45 billion to $235 billion, which is at least as much as noise damages. Our review of applicable measures suggests that effective policies should combine economic incentives, information campaigns, and enforcement measures, coupled with preventive environmental measures.

working paper

A Car-Following Theory for Multiphase Vehicular Traffic Flow

Publication Date

August 31, 2003

Author(s)

Michael Zhang

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

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Abstract

We present in this paper a new car-following theory that can reproduce both the so-called capacity drop and traffic hysteresis, two prominent features of multiphase vehicular traffic flow. This is achieved through the introduction of a single variable, driver response time, that depends on both vehicle spacing and traffic phase. By specifying different functional forms of response time, one can obtain not only brand new theories but also some of the well-known old car-following theories, which is demonstrated in this paper through both theoretical analyses and numerical simulation.

working paper

A New Gridding Method for Zonal Travel Activity and Emissions Using Bicubic Spline Interpolation

Publication Date

August 31, 2003

Author(s)

Michael Zhang, Debbie Niemeier

Areas of Expertise

Zero-Emission Vehicles & Low-Carbon Fuels

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Abstract

For air quality dispersion models, mobile source emissions, including both link- and traffic zone-level emissions, must be disaggregated into grid cells. Current gridding methods assign all traffic analysis zone level emissions to the single grid cell containing the TAX centroid. In this study, we propose a new approach for disaggregating traffic analysis zone-level emissions using a bicubic spline interpolation function and activity and roadway densities. The new approach, which betters replicates the heterogeneity associated with travel activities, distributes zone-level emissions into the grid cells contained within the zone boundary. When results are compared to the current methods, we find that fewer grid cell misallocations occur and that emissions from TAZs overlapping multiple grid cells are apportioned correctly. The gridded emission inventory developed using the new approach will result in better data inputs for air quality modeling, and in particular can significantly improve transportation conformity analysis.

working paper

The Value of Time and Reliability: Measurement from a Value Pricing Experiment

Publication Date

August 31, 2003

Author(s)

Terence Lam, Kenneth Small

Areas of Expertise

Transportation Economics, Funding, & Finance Travel Behavior, Land Use, & the Built Environment

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Abstract

We measure values of time and reliability from 1998 data on actual behavior of commuters on State Route 91 in Orange County, California, where they choose between a free and a variably tolled route. For each route at each time of day and for each day of the week, the distribution of travel times cross different weeks is measured using loop detector data. The best-fitting models represent travel-time by its median and unreliability by the difference between the 90th percentile and the median. We present models of route choice both alone and combined with other choices, namely time of day, car occupancy, and installation of an electronic transponder. In our best model, containing all these choices except time of day, value of time (VOT) is $22.87 per hour, while value of reliability is $15.12 per hour for men and $31.91 for women. These values are 72%,48%, and 101%, respectively, of the average wage rate in our sample.

working paper

Truck-Involved Crashes and Traffic Levels on Urban Freeways

Publication Date

August 31, 2003

Author(s)

Thomas Golob, Amelia Regan

Areas of Expertise

Freight, Logistics, & Supply Chain Safety, Public Health, & Mobility Justice

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Abstract

Using two years of crash and average annual daily traffic data we examine the locations and conditions linked to truck-involved crashes (accidents). A binomial logit model is used to describe how the probability that a crash involves a truck is a function of the percentage of annual average daily traffic that is accounted for by trucks, time of day, day of the week, weather conditions, mix of truck types, and the absolute level of average annual daily traffic. That model can then be used to identify locations with higher or lower than expected truck involved accident rates, controlling for all of the factors that influence truck crash rates. A multinomial logit model was then estimated in order to better understand patterns of truck-involved crashes by separating crashes by type, with the main types being rear-end, lane-change, and run-off collisions. We propose that results from applications of these kinds of models, applied in a specific region, can be useful to public agencies seeking to identify and remedy problem areas either with better driver education or investments in physical or intelligent transportation system infrastructure.

journal article preprint

Used Oil Policies to Protect the Environment: An Overview of Canadian Experiences

Publication Date

August 31, 2003

Author(s)

Hilary Nixon, Jean-Daniel Saphores

Areas of Expertise

Other Zero-Emission Vehicles & Low-Carbon Fuels

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Abstract

We examine some consequences of dumping used oil in the environment and review some policies to foster used oil recycling. We then contrast policies adopted in the Canadian Prairie Provinces for managing used oil, used oil filters, and containers, with those put in place in the rest of Canada. Our analysis proposes that public-private partnerships relying on economic instruments and public education can be more effective for recycling used oil than public agencies relying mostly on regulations.

working paper

On the Structure of Weekly Activity/Travel Patterns

Publication Date

August 31, 2003

Author(s)

Ming-Sheng Lee, Michael McNally

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

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Abstract

Understanding the process of activity scheduling is a critical prerequisite to an understanding changes in travel behavior. To examine this process, a web-based activity survey program, REACT!, was developed to collect household activity scheduling data. REACT! is unique in that it records the evolution of activity schedules from intentions to final outcomes for a multi-day period. This paper summarizes an investigation of the structure of activity/travel patterns based on a REACT! data set from a pilot study conducted in Irvine, California. The term structure refers to the outcome of a set of decisions facing individuals as they conduct their daily activities. At a minimum, structure can be interpreted as the sequence by which various activities enter one’s daily activity scheduling process. Results of the empirical analyses show that activities of shorter duration were more likely to be opportunistically inserted in a schedule already anchored by longer duration counterparts. Additionally, analysis of tour structure reveals that many trip-chains were formed opportunistically. Travel time required to reach an activity was also positively related to the scheduling horizon for the activity, with more distant stops being planned earlier than closer locations.

working paper

A Method for Relating Type of Crash to Traffic Flow Characteristics on Urban Freeways

Publication Date

July 31, 2003

Author(s)

Thomas Golob, Will Recker

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Safety, Public Health, & Mobility Justice

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Abstract

A method is developed to determine how crash characteristics are related to traffic flow conditions at the time of occurrence. Crashes are described in terms of the type and location of the collision, the number of vehicles involved, movements of these vehicles prior to collision, and severity. Traffic flow is characterized by central tendencies and variations of traffic flow and flow/occupancy for three different lanes at the time and place of the crash. The method involves nonlinear canonical correlation applied together with cluster analyses to identify traffic flow regimes with distinctly different crash taxonomies. A case study using data for more than 1,000 crashes in Southern California identified twenty-one traffic flow regimes for three different ambient conditions: dry roads during daylight (eight regimes), dry roads at night (six regimes), and wet conditions (seven regimes). Each of these regimes has a unique profile in terms of the type of crashes that are most likely to occur, and a matching of traffic flow parameters and crash characteristics reveals ways in which congestion affects highway safety.