Information quality management (IQM) is crucial in critical Information and Communications Technology (ICT) systems since our lives and health often depend on the quality of information that the systems provide. Especially in the field of transport, we can speak about critical systems. Worldwide, a small number of scientists take on these problems. This is because information quality (IQ) measurement is a very complex process, and IQM is impossible without IQ measurement. In the article, the authors used a method for IQ measurement created by one of them. This method for IQ measurement makes it possible to create IQM and IQ assessment (IQA). This article proposes a method for IQA that makes IQM possible. The authors demonstrated the possibility of searching for IQ modelling imperfections and offered a computation example for a road traffic light power system. In the final section authors present simulation results for two models. The results of this research can be used to optimise information flow. Employing IQA to evaluate ICT systems will enable controlling the maintenance of adequate IQ, among others, after changes to an ICT system or locating the quality models’ weakest or improper elements. The novelty of the presented IQM method is using multi-layer IQA based on uncertainty modelling.