Senior European intelligence and security officials have expressed increasing concern in recent months that terrorists would make targets of the still relatively open rail networks of a region that depends heavily on passenger rail transport. In the aftermath of Thursday’s terrorist bombings in Madrid, European leaders and security officials were tightening security at train and subway stations across the region, stepping up police patrols, bomb-detection measures and electronic surveillance. Passenger rail traffic in Europe is more than 12 times the level in the United States, according to European Union figures, and Europe is surpassed in passenger miles only by China and Japan. Full Story