The Department of Homeland Security (DHS) is still investigating a recent incident in which a large pipe bomb was found floating in Lake Pontchartrain, north of New Orleans. The device was examined, it was definitely a floating bomb, and was detonated while still on the water. While not a large explosive device, it reminded everyone at DHS that a major terrorist threat is the destruction of one of the railroad bridges over the Mississippi river. These bridges carry a major amount of freight traffic, and the loss of even one of them (if only for a few weeks, while being repaired) would have a noticeable effect on the economy. Al Qaeda knows about this, thus counter-terrorism officials are trying to found out who made the Lake Pontchartrain bomb. That's because this device had all the hallmarks of a test, for a larger bomb capable of dropping one of the nearby Mississippi river bridges.