Using Network Disruptions to Measure System Robustness

Principal Investigator: David Novak (UVM Transportation Research Center)
Funding Agency: New England University Transportation Center at Massachusetts Institute of Technology (NEUTC at MIT)

Project Summary

Transportation planning efforts, especially those involving highway capacity expansions, have traditionally relied on the volume/capacity (V/C) ratio to identify "highly congested" or critical links, resulting in localized solutions that do not consider system-wide impacts related to congestion, security, and emergency response. The Network Robustness Index (NRI) model described in this proposal is a new, comprehensive, system-wide approach to identifying critical links and evaluating network performance that relies on readily available sources of data from transportation demand planning models.

The NRI measures solutions system-wide benefits rather than local benefits such as volume to capacity ratios. This research is based on the premise that a fundamental change in highway network design philosophy is needed. Instead of identifying individual congested or critical links based on localized measures, such as level of service, we argue that infrastructure management should focus on maximizing the robustness of the overall transportation system or on minimizing the system vulnerability. In the proposed research, we address the need improve the NRI to account for sparsely connected nodes/areas that have only one link connecting them to the remainder of the network. This limitation in the formulation of the NRI currently precludes calculation of the index for all possible links.