## 4 Intelligent Wearable Solutions for VRU Safety: Trends, Challenges, and Opportunities
### Wearable Safety Solutions for Pedestrians  
Eleven research papers have focused on utilizing wearable technology to enhance pedestrian traffic safety (Table 6), with three targeting elderly pedestrians [30, 31, 32] and two addressing mine workers [33,34]. Existing wearable devices in these studies can be categorized into haptic feedback devices, such as vibrotactile wristbands [30,31]; auditory feedback devices, including bone conduction headphones [31] and wearable headsets [35]; visual feedback devices, such as AR systems [31,36,37,38,39] and VR headsets [32]; smart protective equipment, including smart glasses [33] and helmets [34]; and wearables with integrated radar sensors [40]. In these studies, [PERSON] et al. conducted the earliest research targeting elderly pedestrians, developing a vibrotactile wristband in 2017 that significantly improved street-crossing safety for older adults [30], particularly reducing collision risks for older women in far lanes and with fast-approaching vehicles. This tactile system effectively addressed cognitive deficits in elderly people's perception of vehicle gaps. Building on this initial experience, the research of [PERSON] et al. further compared vibration wristbands, bone conduction headphones, and AR visual feedback for elderly navigation [31], finding all sensory assistance methods superior to traditional paper maps. Among these, combined audiovisual feedback devices proved especially effective for the oldest elderly participants. [PERSON] et al. used head-mounted displays to conduct perception training for elderly individuals in virtual street-crossing tasks [32]. The research demonstrated that different auditory cues could effectively guide older adults to reallocate attention to specific or non-specific visual information during street-crossing decisions. This finding provided new directions for perceptual training in developing road safety interventions for the elderly. Beyond research focused on older adults, wearable devices for pedestrian safety in specialized work environments have also received attention. [PERSON] et al. developed a smart glasses system that accurately receives proximity warnings from heavy equipment or vehicles via Bluetooth beacons [33], delivering visual feedback to workers. The system effectively detects equipment at distances of at least 10 m regardless of pedestrian orientation, achieving a 100% alarm success rate in all 40 tests [33] while maintaining workers' efficiency. Subsequently, [PERSON] et al. from the same research team further developed a smart helmet system [34], also using Bluetooth beacons to receive vehicle approach information but providing visual warnings through LED light strips. Compared to smart glasses, smart helmets not only reduced workers' cognitive burden and stress while freeing their hands to maintain work efficiency but also scored lower in calculated overall workload ratings, demonstrating superior user experience. Meanwhile, research into wearable devices and augmented reality technology for pedestrian safety in ordinary road environments has also deepened. [PERSON] et al. developedan AR warning system that provides collision risk information to pedestrians through wearable glasses [36]. The system displays vehicle paths, conflict points, and collision times in real time, guiding attention through elements such as sidebars and arrows, particularly suitable for pedestrians with obstructed views or low situational awareness, providing timely and intuitive warning information. The experiments of [PERSON] et al. revealed the impact of matching distraction with warning modality [37], finding that when distraction and warnings use different sensory channels (visual and auditory), pedestrians exhibit more cautious street-crossing behavior, including reduced walking speed, expanded visual scanning range, and faster responses to vehicles. Furthermore, [PERSON] et al.