Road Tunnel Positioning: Enabling Location-Based Services in GNSS-Denied Environments

Navigation services and other traffic applications are nowadays widespread, and their use is very common. These applications have an impact on traffic flow, driver awareness, and driver safety; however, a determination of the actual position of the end device is required. Most of such applications use Global Navigation Satellite Systems (GNSS), which cover a significant part of the transport infrastructure. However, in a GNSS-denied environment, these commonly used methods are either unavailable or significantly limited.For example, in road tunnels, signals are blocked by the tunnel structure itself. Nevertheless, tunnels are part of critical infrastructure and, in addition, have higher requirements to ensure safety compared to other transport routes. This article proposes an alternative method to determine position using data from additional Bluetooth Low Energy infrastructure. Furthermore, the localization approaches are presented together with the evaluation and its accuracy and stability assessment. The localization infrastructure was tested at various speeds during tunnel closure and during the real traffic scenario. The median positioning error ranges between 15-20m and decreases with distance, providing a stable, reliable, and cost-effective solution, particularly suited for long tunnels with varying curvatures. Therefore, it offers a practical use with significant impact on traffic safety and efficiency.