Validation of a novel virtual reality platform for investigating pedestrian-pedestrian interaction in the context of structural vibration serviceability

Pedestrian-pedestrian interaction (PPI) is one of the fundamental mechanisms purported to influence the amplitudes of structural response under the action of a walking crowd. This is because a pedestrian is likely to alter their gait due to the presence of other pedestrians, which in turns alters the magnitude of structural loading. However, little empirical data are currently available to assess the effect of PPI in the context of vibration serviceability. This is mainly due to logistical challenges in assembling and instrumenting a crowd of walking pedestrians, and the associated cost. To this end, a novel virtual reality platform is developed for experimental investigation of pedestrian-pedestrian interaction. In comparison to real-world crowd testing, the platform enables experimental protocols to be implemented repeatedly in a highly controlled environment while collecting a rich set of data on pedestrian behaviour. The platform incorporates state-of-the-art technology for motion capture, artificial intelligence and three-dimensional computer modelling, and comprises of three core modules: (i) the environment, (ii) the crowd and (iii) the user interface enabling real walking behaviour. To assess the validity of the platform for investigating PPI, tests were conducted to quantify gait synchronisation between a pair of walking pedestrians. The pair of pedestrians consisted of either two real humans or a real human and an avatar generated within a fully immersive VR environment. The test subject was either not explicitly asked to or specifically asked to synchronise their gait while walking side-by-side or front-to-back. It was found that walking with an avatar yields qualitatively the same results as walking with a real person, whether that is with or without the instruction to synchronise gait. However, the results differ quantitatively in terms of the synchronisation strength and the directionality.