Building effective vehicular cyber-physical systems to improve road safety is a non-trivial challenge. The abnormal region of road – ‘road abnormal region’ – is one of the main reasons for traffic congestion and thus should be taken into account in order to inform the design of a road monitoring mechanism and navigation service. The characteristics of the abnormal region (AR) are investigated in this paper and an evaluation criterion is suggested. AnyLogic 6.0 (Education) is the platform used to simulate the generation of AR and its changing procedure, which provides justification for the proposed algorithm.