01014825

Component

https://doi.org/10.3141/1917-13

http://scholar.google.com...Wang&publication_year=2005

The Washington State Department of Transportation (WSDOT) has a loop detection system on its Greater Seattle freeway network to provide real-time traffic data. The dual-loop detectors installed in the system are used to measure vehicle lengths and then classify each detected vehicle into one of four categories according to its length. The dual loop’s capability of measuring vehicle length makes the loop detection system a potential real-time truck data source for freight movement studies because truck volume estimates by basic length category can be developed from the vehicle length measurements produced by the dual-loop detectors. However, a previous study found that the dual-loop detectors were consistently underreporting truck volumes, whereas the single-loop detectors were consistently overcounting vehicle volumes. As an extension of the previous study, the research project described here investigated possible causes of loop errors under nonforced-flow traffic conditions. A new dual-loop algorithm that can address these error causes and therefore tolerate erroneous loop actuation signals was developed to improve the performance of the WSDOT loop detection system. A quick remedy method was also recommended to address the dual-loop undercount problem without replacing any part of the existing system hardware or software. In addition, a laptop-based detector event data collection system (DEDAC) that can collect loop detector event data without interrupting a loop detection system’s normal operation was developed in this research. The DEDAC system enables various kinds of transportation research and applications that could not otherwise be possible.

01014803

English

0000-0002-4180-5628

pp 108-115

2005

Transportation Research Record: Journal of the Transportation Research Board

0309093902

Print

Figures (3) ; References (14) ; Tables (3)

Algorithms; Data collection; Errors; Freeways; Laptop computers; Loop detectors; Real time information; Trucks; Vehicle classification; Vehicle length

Dual loop detectors; Undercounting

Seattle (Washington)

Highways; Motor Carriers; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning

TRIS, TRB, ATRI

Dec 27 2005 11:39AM

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