Traffic Monitoring Using Optical Fiber Distributed Acoustic Sensing for Metropolitan Environments

Traditional traffic monitoring technologies, for Intelligent Transportation Systems (ITS), are often constrained by limited coverage, invasive installations, and privacy concerns. In recent years, optical fiber distributed acoustic sensing (DAS) has emerged as an innovative solution, leveraging optical fibers in existing telecommunication infrastructure to create a low-cost, comprehensive, and non-intrusive traffic monitoring network. This enables high-resolution, real-time surveillance of road traffic conditions over extensive distances. This paper provides an overview of the fundamental principle of DAS and the physical model for vehicle-induced vibrations and detection by DAS. Particularly focused on urban metropolitan environments, we then proposed a few techniques to enhance signal quality for high-density traffic environments, including co-routed signal combination, the Superlets transform-based frequency analysis, and the block normalization. Furthermore, we achieved lane detection, coarse weight estimation and axle detection. Together, they enhance the effectiveness and open up new functionalities of DAS for traffic monitoring in metropolitan areas.