Vulnerable road users (VRUs) face high collision risks in mixed traffic, yet most existing safety systems prioritize driver or vehicle assistance over direct VRU support. This paper presents ARCAS, a real-time augmented reality collision avoidance system that provides personalized spatial alerts to VRUs via wearable AR headsets. By fusing roadside 360-degree 3D LiDAR with SLAM-based headset tracking and an automatic 3D calibration procedure, ARCAS accurately overlays world-locked 3D bounding boxes and directional arrows onto approaching hazards in the user's passthrough view. The system also enables multi-headset coordination through shared world anchoring. Evaluated in real-world pedestrian interactions with e-scooters and vehicles (180 trials), ARCAS nearly doubled pedestrians' time-to-collision and increased counterparts' reaction margins by up to 4x compared to unaided-eye conditions. Results validate the feasibility and effectiveness of LiDAR-driven AR guidance and highlight the potential of wearable AR as a promising next-generation safety tool for urban mobility.

翻译：在混合交通环境中，弱势道路使用者面临较高的碰撞风险，然而现有的大多数安全系统优先考虑驾驶员或车辆辅助，而非直接支持弱势道路使用者。本文提出ARCAS，一种实时增强现实防撞系统，通过可穿戴AR头显为弱势道路使用者提供个性化的空间警报。通过融合路侧360度3D激光雷达、基于SLAM的头显跟踪以及自动3D校准程序，ARCAS能够将世界锁定的3D边界框和方向箭头精确叠加到用户穿透视野中接近的障碍物上。该系统还通过共享世界锚点实现多头显协同。在真实世界行人与电动滑板车及车辆的交互场景中进行评估（180次试验），与裸眼条件相比，ARCAS使行人的碰撞时间几乎翻倍，并将对方反应裕度提升高达4倍。结果验证了激光雷达驱动的AR引导的可行性和有效性，并突显了可穿戴AR作为下一代城市出行安全工具的潜力。