Basically what happens is a hauler job takes trains from the Laredo yard to the international bridge. The KCS crew pulls half way across the bridge, gets off, and the KCSM crew gets on. There is a X-ray machine on the US side to check every inbound train as well as custom officials on both sides. Trains are inspected in the Laredo yard with dogs and special agents. All trains out of Laredo are stopped and inspected in route at a specific location.