Characterising vulnerable road user evasive manoeuvring in real-world crashes: Injury risk implications

Most collision data involving vulnerable road users (VRUs) is sampled based on the presentation of injury or relies on police-reported collisions, which serves to capture higher severity events while failing to include vehicle-to-VRU contacts in which VRU avoidance may mitigate injury presentation. Accordingly, when developing risk models from this data, the data censoring can lead to an overestimation of risk, particularly at lower severity levels. The objective of this study was to characterise VRU pre-collision posturing and post-collision outcomes to inform improved risk assessments. Leveraging dash camera video and sensor data from third-party vehicles involved in collisions with VRUs, 522 collisions events were reviewed to assess environmental factors, avoidance behavior, collision features, and post-collision outcomes. Relationships between vehicle speed and VRU knockdown were presented to highlight the additional injury mechanism of falling to the ground. Visual occlusions were observed in approximately 25% of cases. VRUs were considered to observe the impending collision event in 63% of cases and performed an avoidance maneuver in approximately 87% of those cases. These dash camera data highlight that the vehicle being visible to the VRU is critical to having the potential to mitigate collision outcomes. Collisions at speeds exceeding 10 mph are likely beyond the reasonable limits of stability for VRUs to maintain an upright position and avoid potential injury associated with falling to the ground.