Development and field validation of a fully customised vehicle scanning system on two full-scale bridges

Ensuring the structural integrity of bridges is essential for maintaining infrastructure safety and promoting long-term sustainability. In this context, indirect structural health monitoring (ISHM) through drive-by bridge inspection emerges as a promising alternative to traditional inspection methods, offering a cost-effective and scalable solution by leveraging vehicle-mounted sensors to assess the condition of bridges without requiring direct instrumentation. To our knowledge, this study introduces the first purpose-built electric inspection vehicle specifically designed for drive-by bridge inspection. The autonomous platform is capable of maintaining a constant low speed and offers customisable operational parameters to maximise the accuracy and repeatability of indirect sensing capabilities not achieved in previous studies. The vehicle is deployed within an ISHM framework and tested on two full-scale bridges to evaluate its effectiveness in capturing structural dynamic responses. Three rigorous unsupervised frameworks are then employed to analyse the collected data to identify features indicative of bridge properties and structural condition, including adversarial autoencoders, matrix profile and transformer network. The promising findings from this study demonstrate the practical feasibility of the approach. The study underscores the potential of ISHM as a viable tool for efficient bridge monitoring, contributing to the development of next-generation structural health monitoring systems that enhance safety, optimise maintenance strategies and support the longevity of critical infrastructure.