IMPACTS OF THE NORTHRIDGE EARTHQUAKE ON TRAFFIC NETWORK PERFORMANCE

Although freeway infrastructural damage resulting from the January 1994 Northridge earthquake was primarily confined to areas near the epicenter in the San Fernando Valley and also in west Los Angeles, the impact on the flow of traffic was more widespread. The destruction of critical links in the highway transportation network reduced connectivity and available routes and also removed capacity from the system. From the perspective of system operation and performance, two key issues are addressed. First, what fundamental changes in network performance occurred as a direct consequence of the earthquake, and second, at what rate did traffic return in the post-quake recovery period? These issues were addressed in this project through the examination of observed traffic volumes from loop detectors on the southern California freeway network. These results are supplemented by the application of a transportation network model to estimate traffic conditions in locations which are not detectorized. A parallel study objective was to develop, verify, and apply a system of conventional transportation simulation models to the sub-regions most critically impacted by the Northridge earthquake to assess the operation and performance of the highway network in various phases of recovery. This report summarizes the study and its results.