Assessing the importance of transportation facilities is an increasingly growing topic of interest to federal and state transportation agencies. In the wake of recent terrorist attacks and recurring manmade and natural disasters, significant steps are needed to improve security at both state and metropolitan level. This paper proposes a heuristic procedure using concepts of complex networks science to assess the importance of highway transportation networks using travel time as the performance measure to assess criticality. We demonstrate the proposed technique both in a theoretical network (Sioux Falls network) and in a built-up network to assess the criticality of the major infrastructures that are used to access Manhattan in an AM peak hour. The results demonstrate the efficacy of the procedure to determine critical links in a transportation network. © 2009 Springer Science + Business Media, LLC.