01334545

Component

https://doi.org/10.3141/2256-09

http://scholar.google.com...fman&publication_year=2011

.Loop detectors are the most common sensors used to collect freeway management data. There has been considerable research to screen the quality of loop detector data, but some significant detector errors have not received much attention because of the difficulty of identifying their occurrence. This study examines one such error, pulse breakup, in which what should be a single pulse from a vehicle breaks up into two or more pulses because the detector momentarily drops out. An algorithm is developed to identify the presence of individual pulse-breakup events. The algorithm is based on the nature of pulse breakup revealed from individual vehicle actuations with concurrent video ground truth. The algorithm begins with the comparison of the on-times from the two successive pulses bounding a given short off-time. To differentiate between pulse breakup and tailgating, the algorithm includes several comparisons of the adjacent on-times with respect to the ambient traffic conditions. Six steps are included in the algorithm. If two successive pulses satisfy all steps, these pulses are a suspected pulse breakup. Otherwise, these pulses are considered to arise from non-pulse-breakup events. The process is repeated over all pulses at each detector. The results can be used to correct for the suspected pulse-breakup events, and the rate of suspected pulse-breakup events provides an indication of the detector’s health. The algorithm was tested over 68,281 actuations with concurrent video ground truth, in both free-flow and congested conditions, from 15 detector stations (22 directional stations). As presented here, the algorithm demonstrated good performance.

01362484

11-1608

English

pp 68-78

2011

Transportation Research Record: Journal of the Transportation Research Board

9780309222921

Print

Figures (4) ; References (21) ; Tables (2)

Algorithms; Errors; Freeways; Loop detectors; Pulse modulation; Traffic data

Data errors detection

Data and Information Technology; Highways; Operations and Traffic Management; I70: Traffic and Transport

TRIS, TRB

Feb 17 2011 5:52PM

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