This is a different kind of underground railroad. U.S. authorities discovered a huge Mexican drug-smuggling tunnel equipped with lights, ventilation, and electric rail—one of the most sophisticated secret drug passages ever discovered. The tunnel zizags from Tijuana to San Diego and was primarily used to smuggle marijuana, though tons of cocaine were also found. Three drivers were arrested on drug possession charges and face 10 years to life in prison. Authorities put the warehouse on the San Diego end under surveillance after an informant tipped them off that its operators bought drills and construction equipment.