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Title: USING GLOBAL POSITIONING SYSTEM DATA FOR FIELD EVALUATION OF ENERGY AND EMISSION IMPACT OF TRAFFIC FLOW IMPROVEMENT PROJECTS: ISSUES AND PROPOSED SOLUTIONS
Accession Number: 00820958
Record Type: Component
Record URL: Availability: Transportation Research Board Business Office 500 Fifth Street, NW Find a library where document is available Abstract: Traffic-operational projects typically are evaluated by using several measures of effectiveness, including vehicle delay, queue sizes, and vehicle stops. Other emerging measures include vehicle fuel consumption and emissions. Although these emerging measures are difficult to determine in the field, they can be estimated by using second-by-second speed measurements of individual vehicles with Global Positioning System (GPS) technologies. GPS can provide such information with relatively high accuracy (within 1 m/s), but the presence of any erroneous data in the measured data as a result of signal losses may result in unrealistic vehicle fuel consumption and emission estimates. The ability of various data-smoothing techniques to remove such erroneous data without significantly altering the underlying vehicle speed profile is investigated. The techniques reviewed involve differentiating the measured speed profile to generate an acceleration profile that is checked for validity. Several smoothing techniques are then applied to the acceleration profile, including data trimming, simple exponential smoothing, Epanechnikov kernel smoothing, robust kernel smoothing, and robust simple exponential smoothing. The results of the analysis indicate that the application of robust smoothing (kernel of exponential) to vehicle acceleration levels, combined with a technique to minimize the difference between the integral of the raw and smoothed acceleration profiles, removes invalid GPS data without significantly altering the underlying measured speed profile. A sensitivity analysis also demonstrates that the proposed data-smoothing technique can efficiently smooth random variations in speed profiles due to errors in GPS speed measurements.
Supplemental Notes: This paper appears in Transportation Research Record No. 1768, Transportation Data and Information Technology.
Language: English
Corporate Authors: Transportation Research Board 500 Fifth Street, NW Authors: Rakha, HDion, FSin, H-GPagination: p. 210-223
Publication Date: 2001
Serial: ISBN: 0309072301
Features: Figures
(9)
; References
(11)
; Tables
(6)
TRT Terms: Uncontrolled Terms: Subject Areas: Energy; Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning; I73: Traffic Control
Files: TRIS, TRB, ATRI
Created Date: Dec 5 2001 12:00AM
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