Accessibility of Modern Roundabouts: An Intelligent Management System versus a Common Signalization Scheme

Modern roundabouts have become very popular in North America over the last decade. This popularity can be attributed to their great success in Europe and Australia. The prevalence of roundabouts has generated significant debate over their accessibility for pedestrians. With almost uninterrupted traffic flows, it is difficult for the visually impaired to determine safe gaps relying on auditory cues alone. Such crossing is particularly complicated by ambient noises and circulating vehicles on busy roundabouts in urban settings. Various pedestrian signals have been installed at roundabouts overseas. The United States Access Board published a draft guideline proposing pedestrian signals at all roundabout crossings to ensure access for the visually impaired. The roundabout operation is a complex process of transporting multimodal travelers. There are increased interests in harnessing artificial intelligence to address complex issues to improve transportation systems. This research developed a crosswalk signal and introduced fuzzy logic control (FLC) into the signal timing to accommodate all roundabout users. The new system was assessed against the PUFFIN (Pedestrian User-Friendly INterface) under varied geometries and different traffic volumes. The objective was to identify potential treatments for improving roundabout accessibility, safety, and efficiency. The results reveal the FLC controls the signal timing effectively and outperforms PUFFIN from safety and operational perspectives, especially under congested traffic conditions. It significantly decreases pedestrian delay while maintaining adequate vehicle circulation. Multimodal travelers’ needs are satisfied in terms of improved pedestrian accessibility and safety, reduced potential for rear-end collisions, enhanced operational efficiency, and lessened social cost.