PSU TRB Presentations - Week 1

Friday, January 11, 2013, 12:00pm to 1:00pm PST
Steve Gehrke, Katie Bell and Chris Muhs; Portland State University

The video begins at 3:22.

Steve Gehrke (CEE PhD) - Application of Geographic Perturbation Methods to Residential Locations in the Oregon Household Activity Survey: Proof of Concept

Travel demand models have advanced from zone-based methods to favor activity-based approaches that require more disaggregate data sources. Household travel surveys gather disaggregate data that may be utilized to better inform advanced travel demand models and also improve the understanding of how nonmotorized travel is influenced by a household’s surrounding built environment. However, the release of these disaggregate data is often limited by a confidentiality pledge between the household participant and survey administrator. Concerns regarding the disclosure risk of survey respondents to household travel surveys must be addressed before these household-level data may be released at their disaggregate geography. In an effort to honor this confidentiality pledge and facilitate the dissemination of valuable travel survey data, this research: (i) reviews geographical perturbation methods that seek to protect respondent confidentiality; (ii) outlines a procedure for implementing one promising practice, referred to as the donut masking technique; and (iii) demonstrates a proof of concept for this technique on ten respondents to a household activity travel survey in the Portland metropolitan region. To examine the balance between limiting disclosure risk and preserving data utility, four trials were conducted and measures of household anonymity and built environment variation were analyzed for the relocated household in relation to its actual location. Results of this demonstration revealed that increases in the potential displacement distance of a geographically perturbed household generally reduced disclosure risk, but also limited data utility.

Katie Bell (CEE MSCE) - Evaluation of Smart Phone Weight-Mile Tax Truck Data for Supporting Freight Modeling, Performance Measures, and Planning

Oregon is one of the few states that currently charge a commercial truck weight-mile tax (WMT). This research serves to evaluate ancillary applications for a system developed by the Oregon Department of Transportation (ODOT) to simplify WMT collection. The data collection system developed by ODOT –TRUE (Truck Road Use Electronics) –includes a smart phone application with a Global Positioning System (GPS) device and microprocessor. The TRUE data has enormous advantages over GPS data used in previous research due to its level of disaggregation and its potential to differentiate between vehicle and commodity types. This research evaluates the accuracy of the TRUE data and demonstrates the results of its application to develop trip generation rates for a variety of truck types and land use categories. This research also confirms the value of the TRUE data to enhance existing ODOT transportation planning models and performance measures.

Chris Muhs (CEE MSCE) - Evolution of ITE Trip Generation Handbook: Proposal for Collecting Multimodal, Multicontext Establishment-Level Data

This paper outlines a new perspective on data collection to inform site-level trip generation studies with amendments to ITE’s Trip Generation Handbook in mind. The data collection proposed here is informed from the authors’ experiences in a study that aimed to adjust trip generation rates for urban context. In this study, a consistent and reliable method for adjusting ITE’s trip generation rates to account for increased non-automobile travel in different urban contexts was developed. Based upon these experiences, the design presented here proposes more emphasis on collecting information on person counts and how those person trips are distributed across various modes, including walking, cycling and transit. This paper advocates a move away from the vehicle-based counts used historically in these studies, to a focus on how new development impacts all transportation system users.