Abstract: There are a lot of factors influencing road network and lead by transport performance degradation.The influencing factors and mechanism of road network transport performance degradation are analyzed.The cost evaluating process framework of road transport performance degradation and road disruption is given.Road network disruption performance degradation cost model is analyzed based on BPR link performance function and user equilibrium assignment theory.Finally,an example is used to explain the basic law that road network transport performance degradation influences the travel cost,and the specific process of road network transport performance degradation costevaluation The study shows that the road network transport performance degradation has agreat impact on the travel cost,and the transport performance degradation is significant positive correlation to the travel cost.

Key words: road networks, performance degradation, cost evaluation, link performance function, user equilibrium assignment