Possible Threats and Damage

Threats:

Assessment of vulnerability requires consideration of the means of inflicting damage to a facility, that is, the threat or threats. The analogy to the conventional design process is the identification of the design loads. Effective countermeasures and associated costs cannot be developed without this assessment just as the amount of steel and concrete needed in a bridge or tunnel cannot be calculated if the loads are not known. The following types of threats are considered:

• Low-tech and high-tech conventional explosives (e.g., shape charges)
• Explosively formed penetrating devices (EFP, kinetic energy penetrators)
• Low-tech, hand-held cutting devices
• Truck size/barge size conventional explosives
• Chemical/biological agents released in tunnels
• Incendiary conventional explosives
• HAZMAT release in tunnels
• Intentional ramming via ship or barge

Damage

The consequences of attack expressed as damage to bridges and tunnels that are of concern are as follows:

• Threats to the integrity of the structure (e.g., resulting in replacement of the facility or major repairs)
• Damage that inhibits the structure’s functionality for an extended period of time, such as closure of the facility for 30 days or more
• Contamination of a tunnel resulting in extended closure or loss of functionality
• Catastrophic failure resulting from an attack based on the threats described above