access icon free Outlier filtering algorithm for travel time estimation using dedicated short-range communications probes on rural highways

© The Institution of Engineering and Technology
Received 02/06/2015, Accepted 04/02/2016, Revised 07/01/2016, Published 01/08/2016

With increasing market penetration, dedicated short-range communications (DSRC) probes are attracting more interest in the advanced traveller information system as a way to efficiently alleviate traffic congestion. Generally, DSRC probes, thanks to their ability to directly collect point-to-point travel time, are considered to be superior to conventional point detectors. However, outlying observations are inevitable in DSRC probe data, and can erroneously indicate abnormally long travel times. In this study, a practical algorithm to filter out outliers in DSRC probe data is proposed. The suggested algorithm is divided into two parts. In the case of small sample, it uses a previous interval value to determine a valid range for current interval values; otherwise, it uses a modified median filter that uses the median and absolute deviation of current interval observations to determine the valid range. The algorithm has been thoroughly verified using various types of DSRC probe data in interrupted and uninterrupted rural highways near Seoul, Korea. Consequently, it was proven to be sufficient to overcome the deficiencies of the previous techniques.

Inspec keywords: median filters; traffic information systems; mobile radio

Other keywords: point-to-point travel time collection; dedicated short-range communication probes; DSRC probe data; point detectors; outlier filtering algorithm; rural highways; advanced traveller information system; travel time estimation; modified median filter; traffic congestion

Subjects: Digital signal processing; Mobile radio systems; Traffic engineering computing; Filtering methods in signal processing

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