Traffic volume estimation and accuracy evaluation under high traffic conditions using distributed acoustic sensing

Abstract

In this study, we propose a novel traffic volume measurement method that utilizes existing optical fiber cables embedded beneath road surfaces, in addition to conventional methods. Distributed Acoustic Sensing (DAS) enables the observation of strain rate at any point along the entire length of the optical fiber. Using DAS data from optical fiber cables installed along a national highway, it was found that frequency components below 2 Hz were significantly present in the strain rate signals only when vehicles passed through lanes near the cable. Based on this characteristic, we developed a method to easily measure traffic volume from strain rate data with only a low-pass filter applied. Through comparison and verification with traffic census data, we confirmed that this method enables highly accurate estimation. Furthermore, applying corrections for measurement errors observed during traffic congestion further improved the estimation accuracy.