Use of High-Resolution Data to Evaluate the Accuracy of Mean and 85th Percentile Approach Speeds Collected by Microwave Sensors
The Utah Department of Transportation (UDOT) installed various types of microwave sensors to get real-time traffic flow data to determine performance measures at signalized intersections. One type of sensor was designed for improving safety in dilemma zones at signalized intersections. Although it does not have the capability to differentiate between lanes, it has a detection range of up to 600 ft. and the capability to track vehicles approaching the intersection. UDOT desired to use this capability to get added value from their investment by collecting approach volume and speed data from the sensor. In this study the accuracy of approach speeds collected by this sensor was evaluated by comparing sensor data to ground truth data collected by a LiDAR gun with two factors in mind: the number of approach lanes and offset position of the lanes relative to the location of the speed gun. The t-test of means showed that the difference in mean accuracy values was statistically significant at some sites and not significant at other sites. However, the difference was only within ±2.0 mph and not significant for practical use. As for the 85th percentile speeds, the average difference of 85th percentile speeds was -0.43 mph for the sites with more than 50 samples. To compensate for the relatively small number of 85th percentile speed data, the bootstrapping method was performed. This analysis showed that the 85th percentile speeds by the two methods were not significantly different for practical use, their differences being just within 18 ±2.0 mph.
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Supplemental Notes:
- This paper was sponsored by TRB committee ABJ35 Standing Committee on Highway Traffic Monitoring.
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Corporate Authors:
500 Fifth Street, NW
Washington, DC United States 20001 -
Authors:
- Sanchez, Gregory H
- Saito, Mitsuru
- Schultz, Grant G
- Eggett, Dennis L
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Conference:
- Transportation Research Board 96th Annual Meeting
- Location: Washington DC, United States
- Date: 2017-1-8 to 2017-1-12
- Date: 2017
Language
- English
Media Info
- Media Type: Digital/other
- Features: Figures; References; Tables;
- Pagination: 17p
- Monograph Title: TRB 96th Annual Meeting Compendium of Papers
Subject/Index Terms
- TRT Terms: 85th percentile speed; Accuracy; Laser radar; Mean (Statistics); Microwave detectors; Traffic data; Traffic speed; Traffic volume
- Subject Areas: Data and Information Technology; Highways; Operations and Traffic Management;
Filing Info
- Accession Number: 01622925
- Record Type: Publication
- Report/Paper Numbers: 17-00656
- Files: PRP, TRIS, TRB, ATRI
- Created Date: Jan 24 2017 12:03PM