1. INTRODUCTION

The 11 September terrorist attack had cruelly exposed the potential brittleness of the transportation system. A terrorist event involving the system could lead to unprecedented disruption of the global trade system (Flynn, 2006) which would not only involve human casualties, but also economic, political and social impacts, notably the breakdown of the global supply chains and potentially global economic recessions (Greenberg et al., 2006). Indeed, the attack had served an important indicator in raising the awareness of security along the transportation system (Kingdon, 1995).