This literature review provides an overview of numerous big data sources and the data-processing methods that can be used to analyse data for road condition monitoring. It focuses on solutions that allow data to be collected quickly, in real time and repeatedly, e.g. via CAN bus, smartphones, digital imagery, open data, crowdsourced data, satellites etc. Whilst most of these methods and technologies have been in existence for some time, it is only relatively recently that their potential for road condition monitoring has been investigated. Please note that traditional pavement condition measurement equipment for monitoring evenness, friction and bearing capacity etc., which can also produce large amounts of data, is outside the scope of this document. Also included is a summary of several completed or ongoing projects that have utilised many of the big data sources described in this document.