but sources tell abc news that schematics found in osama bin laden's home show that he was fixated on transportation targets. >> it's entirely possible that couriers were bringing bin laden computer disks and other computer material, thumb drives, that might have had plots on them. >> reporter: a new bulletin issued by homeland security and seen by abc news describes al qaeda's chilling plan. as of february 2010 al qaeda was allegedly contemplating hurting people on trains on the tenth anniversary of september 11, 2001. in one version, bin laden was considering tampering with the rails. the train would fall off of the track of either a valley or a bridge. but it turns out key early details of the raid on bin laden's compound were not accurate. bin laden's resistance? that came from his wife who was unarmed. reports of women used as human shields. it did not happen. the heavy resistance that met the navy s.e.a.l.s, not so much. in fact most of the gunfire came