Dynamic Signs and Variable Speed Limits to Enhance Road Safety and Traffic Efficiency

The continuous expansion of the Internet of Things (IoT), Big Data systems, and Information and Communication Technologies (ICTs) has transformed traditional road infrastructure, leading to the development of "Smart Roads." These roads interact with vehicles through data exchanges to enhance traffic efficiency o and safety. For instance, in adverse weather conditions like rain or fog, temporary speed reductions communicated via in-vehicle systems or Variable Message Signs (VMS) can restore safety levels. This paper introduces an innovative algorithm for determining the maximum allowable speed on a road segment through real-time analysis of geometric and environmental factors. The system aims to proactively mitigate accident risks caused by non-ideal conditions by dynamically adjusting speed limits. A case study on the Grande Raccordo Anulare (A90) in Rome, a heavily trafficked highway, illustrates the algorithm's application. The methodology involves a detailed geometric modeling of the A90 and analysis of weather conditions, leading to adaptive speed recommendations. Results indicate that dynamic speed management can significantly reduce accident rates by ensuring that the available sight distance exceeds the stopping sight distance under various conditions. Implementing this system with VMS and on-board units can effectively communicate real-time speed adjustments to drivers, promoting safer and more efficient road usage.