Urban transport (buses, subways, commuter rail, water transport, automobiles, and trucks)—In order to be functional open systems with free access, a substantial risk is incurred, since these systems have such a high concentration of users. Motor vehicles are an even greater risk, since their flexibility of movement allows them to serve as effective weapons delivery systems.
Railroads—The wide extent of rail facilities, their open and unprotected nature, and their use in transporting hazardous materials that are essential to urban life, such as the chlorine used for water purification, also makes them an attractive target.
Urban ports—Container movements are the key to low-cost movement of concentrations of goods in international trade, but containers are equally effective carriers of weapons of mass destruction. Similar concerns exist about energy transportation facilities, particularly the handling of liquefied natural gas.
Terrorist attacks in the transport environment can take a number of forms, further complicating the task of prevention and response. Among the forms are
vehicles used as weapons to deliver explosives or other materials against a target
attacks on a transport vehicle and its passengers
attacks on transportation facilities, such as railway or bus stations, where large numbers of passengers may congregate
attacks on transportation infrastructure, such as bridges, railbeds, or signal systems; these attacks could include cyberattacks on transportation control systems
While there is much to be done, governments are taking steps to develop a response to the risk of terrorism, using a variety of methods, including the application of technology, such as
investments in security systems—systemwide improvements to track and protect the movements of goods and people
technology development—new technologies to detect and, where possible, protect against explosives, chemicals, and other weapons in the urban setting
regulatory measures—new rules for the movement of hazardous materials, handling of containers, information flows about movements, and so forth
improved response capability—steps to train, equip, and improve the capabilities of first responders, transportation system employees, and the public as a means of mitigating the impact of terrorist actions