Freight is a community-made, now official map made by Jamie "Fishbus" Manson and Mitch "Ol" Robb. The map is similar to the design of Well, with underwater routes and trains around the mid point. The map was adopted by Valve and made an official map on April 28, 2010 due to its popularity in both pub and competitive play. 5 years later the creator came back and made the slightly improved final_r3 version.
~More info on Comp.tf