Abstract: This invention relates to a vehicle-based infrastructure diagnostic apparatus to assist in the maintenance of rail networks. This is a complete system—from the acquisition of vibration signals in a moving vehicle, to the presentation of the infrastructure changes to the maintenance workers. This apparatus relies on novel techniques to account for the variable speed of the train (making it useful even on non-dedicated rail vehicles) and novel techniques to normalize for various environmental conditions. This system could help maintenance departments identify and remediate anomalies more rapidly, as well as trace network deterioration over time. The apparatus consists of low-cost unobtrusive sensors, software for data analysis, and hardware that makes it easy to deploy widely even on existing rail networks.