01049549

Component

Accurate turning movement counts at signalized intersections are essential for retiming an intersection or corridor and also important for identifying trends in traffic data. In recent years, technology has emerged that can provide vehicle counts at the stop bar without sacrificing the performance of presence detection. The performance of these count detectors was investigated in two studies, which are reported in this paper. The studies involved the comparison of manual counts from recorded video with automated counts obtained from stop bar count detectors at a signalized intersection. These stop bar detectors are historically very difficult to obtain accurate count data from due to their long length (~50 ft) and tendency for multiple vehicles to concurrently occupy the detection zone. Recently, new detector amplifiers have been introduced that are designed to analyze the inductance profile to provide better stop bar counts. The first part of the study looked at count performance as a function of lane geometry and detector placement in the lane using data captured over a number of 24-hr periods. The placement of count detectors in relation to the lane lines was found to be a major factor in count accuracy leading to recommendations for sensor placement. The second portion of the study examined count detector performance under free-flowing and queued traffic regimes. A state of the art counting algorithm was observed to over count in the queued regime. Analysis of the relative change in inductance signature indicated a clearly defined signature was observable during free flow conditions, but the signature during saturated flow regime was quite complex an required more sophisticated analysis. It is expected that stop bar detection algorithms could be further enhanced if phase status information was provided to the count detector amplifier.

01042056

07-1090

English

20p

2007

Transportation Research Board 86th Annual Meeting

CD-ROM

Figures; Photos; References (8) ; Tables (2)

Algorithms; Loop detectors; Operations; Signalized intersections; Stopping; Traffic counts; Traffic data; Traffic flow; Traffic signal timing; Turning lanes

Traffic regimes

Administration and Management; Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2007 Paper #07-1090

TRIS, TRB

Feb 8 2007 5:42PM