Attacks likely will increase as the bombing of oil or gas pipelines can have a significant economic and environmental impact.
Highways. In 1998, highways were the most frequent, and the second most lethal transportation target. There were 242 attacks against highways in 1998, an increase of eighty percent from 1997. Highways comprised 24 percent of worldwide violence against transportation. Eleven of these incidents were international terrorist attacks. The increased number of incidents is a result of insurgencies in Algeria, Turkey, and Colombia, and likely better reporting of such attacks. The number of casualties, 579 killed and 336 injured, attest to the lethality of these attacks. The two most popular tactics used in highway attacks are: 1) mining/bombing, which indiscriminately targets all passing vehicles and pedestrians, be they civilian or military, when they explode; 2) armed attacks at roadblocks, where terrorists disrupt all transportation along a highway, hijack vehicles, rob passengers, steal cargo, take hostages, and/or destroy vehicles and kill passengers.
Bridges and Tunnels. There were twenty-two attacks against bridges and four attacks against tunnels in 1998. One bridge incident was an international terrorist attack. All but one of the attacks on bridges were bombings. Ten people were killed and fourteen were wounded in these incidents. Europe experienced the greatest number of attacks. This was a direct result of unrest in Bosnia and Kosovo. While attacks on bridges and tunnels--and pipelines--do not target civilian populations to create mass casualties, their impact is often significant. Attacks against bridges and tunnels disrupt the economic and transportation infrastructures, isolate agricultural or manufacturing regions from important markets; cut-off needed supplies or reinforcements; and/or cut off communications between population centers and outlying areas. Moreover, repairing or rebuilding critical transportation infrastructures can be costly in terms of time, financial, and manpower resources.
IV. TACTICS-TYPE OF ATTACK AGAINST TRANSPORTATION