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Stevens Point, TX, United States

Fulper C.R.,U.S. Environmental Protection Agency | Kishan S.,Eastern Research Group | Baldauf R.W.,U.S. Environmental Protection Agency | Baldauf R.W.,National Risk Management Research Laboratory | And 10 more authors.
Journal of the Air and Waste Management Association | Year: 2010

Mobile sources significantly contribute to ambient concentrations of airborne particulate matter (PM). Source apportionment studies for PM 10 (PM ≤ 10 μm in aerodynamic diameter) and PM2.5 (PM ≤ 2.5 μmin aerodynamic diameter) indicate that mobile sources can be responsible for over half of the ambient PM measured in an urban area. Recent source apportionment studies attempted to differentiate between contributions from gasoline and diesel motor vehicle combustion. Several source apportionment studies conducted in the United States suggested that gasoline combustion from mobile sources contributed more to ambient PM than diesel combustion. However, existing emission inventories for the United States indicated that diesels contribute more than gasoline vehicles to ambient PM concentrations. A comprehensive testing program was initiated in the Kansas City metropolitan area to measure PM emissions in the lightduty, gasoline-powered, on-road mobile source fleet to provide data for PM inventory and emissions modeling. The vehicle recruitment design produced a sample that could represent the regional fleet, and by extension, the national fleet. All vehicles were recruited from a stratified sample on the basis of vehicle class (car, truck) and model-year group. The pool of available vehicles was drawn primarily from a sample of vehicle owners designed to represent the selected demographic and geographic characteristics of the Kansas City population. Emissions testing utilized a portable, light-duty chassis dynamometer with vehicles tested using the LA-92 driving cycle, onboard emissions measurement systems, and remote sensing devices. Particulate mass emissions were the focus of the study, with continuous and integrated samples collected. In addition, sample analyses included criteria gases (carbon monoxide, carbon dioxide, nitric oxide/nitrogen dioxide, hydrocarbons), air toxics (speciated volatile organic compounds), and PM constituents (elemental/organic carbon, metals, semi-volatile organic compounds). Results indicated that PM emissions from the in-use fleet varied by up to 3 orders of magnitude, with emissions generally increasing for older model-year vehicles. The study also identified a strong influence of ambient temperature on vehicle PM mass emissions, with rates increasing with decreasing temperatures. Source


Bricka S.G.,Texas Transportation Institute | Sen S.,NuStats | Paleti R.,University of Texas at Austin | Bhat C.R.,University of Texas at Austin
Transportation Research Part C: Emerging Technologies | Year: 2012

Recent advances in global positioning systems (GPS) technology have resulted in a transition in household travel survey methods to test the use of GPS units to record travel details, followed by the application of an algorithm to both identify trips and impute trip purpose, typically supplemented with some level of respondent confirmation via prompted-recall surveys. As the research community evaluates this new approach to potentially replace the traditional survey-reported collection method, it is important to consider how well the GPS-recorded and algorithm-imputed details capture trip details and whether the traditional survey-reported collection method may be preferred with regards to some types of travel. This paper considers two measures of travel intensity (survey-reported and GPS-recorded) for two trip purposes (work and non-work) as dependent variables in a joint ordered response model. The empirical analysis uses a sample from the full-study of the 2009 Indianapolis regional household travel survey. Individuals in this sample provided diary details about their travel survey day as well as carried wearable GPS units for the same 24-h period. The empirical results provide important insights regarding differences in measures of travel intensities related to the two different data collection modes (diary and GPS). The results suggest that more research is needed in the development of workplace identification algorithms, that GPS should continue to be used alongside rather than in lieu of the traditional diary approach, and that assignment of individuals to the GPS or diary survey approach should consider demographics and other characteristics. © 2011 Elsevier Ltd. Source


Simas Oliveira M.G.,GeoStats LP | Vovsha P.,Parsons Brinckerhoff | Wolf J.,GeoStats LP | Birotker Y.,Jerusalem Transportation Master Plan Team | And 2 more authors.
Transportation Research Record | Year: 2011

The paper describes recent experience with the application of an innovative Global Positioning System (GPS)-assisted prompted recall (PR) method for a large-scale household travel survey (HTS) in Jerusalem, Israel. The survey was designed to support development of an advanced activity-based model (ABM). The requirements for an HTS to support an advanced ABM are discussed, and the corresponding decisions for survey methods are substantiated. Development of an advanced ABM requires individual records for the entire daily pattern without gaps, missing trips, overlaps, or other data inconsistencies found in a conventional HTS. A consistent record of joint activities and trips of multiple household members is essential. In addition, high levels of spatial and temporal resolution are required. The GPS-assisted PR survey has been identified as the most promising methodology for meeting these requirements. The experience of the first phase of the Jerusalem HTS in 2010 proved the feasibility of the GPS-PR method for all population sectors including specific Orthodox Jewish and Arab populations, which typically featured large household sizes. Various structural comparisons of trip and tour rates obtained during the first phase of the Jerusalem GPSassisted HTS (3,000 households) with the non-GPS surveys previously implemented in Jerusalem and several metropolitan regions in the United States as well as comparisons between the GPS and non-GPS subsamples within the Jerusalem HTS were made. The results confirmed the ability of the GPS-PR approach to create full and consistent daily records of individual activity travel patterns and practically eliminate the underreporting issues that have plagued HTS. Source


Oliveira M.G.S.,GeoStats LP | Casas J.,NuStats
Transportation Research Record | Year: 2010

Transit agencies conduct origin-destination on-board surveys periodically to gather information regarding travel patterns and demographic data of their users and to collect customer satisfaction information. These surveys constitute a highly valuable means of obtaining important information on an agency's customers to provide a basis for effective transit planning and for regional travel demand modeling efforts. This paper describes the application of innovative technologies in the data collection process to improve data quality, data completeness, and data collection management. This includes the simultaneous collection of boarding and alighting count data at the stop level using Global Positioning System-enabled personal digital assistants, association of distributed surveys to boarding locations, and a web-based sample and productivity management system. These technologies allow for automatic collection of boarding location, arrival and departure times, and transit trip times. An imputation procedure was developed to derive the most likely alighting location of each collected sample. Joint application of these technologies reduces survey length and thereby minimizes respondent burden. Source


Chiao K.-A.,The Water Council | Argote J.,The Water Council | Zmud J.,RAND Corporation | Hilsenbeck K.,NuStats | And 2 more authors.
Transportation Research Record | Year: 2011

Funding constraints limit the ability of local and state agencies to fund quality data collection efforts. At the same time, public agencies that oversee transportation programs must support planning and policy making with empirical data. As a result, transportation data users and suppliers are consistently pressed to find better, faster, and cheaper ways of collecting data. Thus, continuous improvement in travel survey data methods, procedures, and tools is an imperative, not a luxury. This paper presents the implementation and results of a continuous improvement process directed by the New York Metropolitan Transportation Council (NYMTC) with regard to its regional household travel survey. The paper reports on how lessons learned from NYMTC's 1997-1998 household travel survey along with feedback from respondents were used to plan and design the 2010 household travel survey. New methods and tools that were implemented in a 2010 survey pretest are identified, and conclusions concerning the recommended survey design are provided. Source

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