Although there have been efforts to achieve the zero deaths on horizontal construction projects, undesired crashes within work zones continue to happen, highlighting the need for continuous studies on work zone safety improvements. An advantageous tool to be used in such studies is the Virtual Reality (VR) technology, as it provides a safe and highly realistic environment for performing behavioral experiments without endangering the participants. However, researchers still face the challenge of integrating real-world traffic data and interactions in VR back to simulation environments. Hardware-in-the-loop (HIL) is a testing paradigm where physical sensors (e.g., work zone traffic/worker monitoring sensors, worker notification sensors) are connected to a virtual test system that simulates reality (e.g., virtual work zone with simulated dangerous situations). This paradigm is well-suited for conducting user studies for work zone safety because virtual test systems can be implemented using VR, which allows for safe and realistic testing of a sensing system without putting workers in danger along with avoiding high upfront cost needed to generate research test beds in real world. Traffic simulations can be developed to replicate realistic traffic patterns based on physical characteristics of the road and vehicles, but a two-way link between traffic simulation and VR has yet to be established.
This study presents the development of an integrated platform that allows a two-way interface between traffic simulation and VR environments. The integrated platform enables both applications to spontaneously interact with each other to represent realistic traffic and work zone conditions in the VR environment. The main contribution of this study is the development of the integrated and immersive platform and its customized API tool, called Traffic Simulation-Virtual Reality Integration (TSVRI). The TSVRI API, which bidirectionally transfers information between simulation and VR in real-time, guarantees that the VR environment represents the dynamic characteristics of the work zone traffic and user interactions are fed back to the simulation model to continuously update the traffic information. The integrated platform was tested in alpha experiments and shown to be effective to reproduce realistic traffic scenarios, scalable to different work zone settings (long-, intermediate-, short-term, or mobile), and is ready to be used in experiments with a higher number of participants with different construction experience.