Regarding to the requirements for effectively traffic incident management on freeway with the knowledge of previous emergency cases
an ontology based model of freeway traffic emergency cases is constructed.This model provides a unified semantic representation of the development stages of freeway traffic incident as well as the handling processes
among heterogeneous systems deployed in different areas or departments of freeway;and better facilitate the sharing and application of the knowledge of previous emergency cases.To illustrate the usage of this ontology based model
a freeway traffic emergency cases sharing system is sketched
and a typical traffic emergency case is formally described as an ontology instance for joint emergency rescue on freeway.