The Korail Class 311000 trains, formerly numbered as Korail Class 5000 trains, are commuter electric multiple units in South Korea used on Seoul Subway Line 1. Class 311000 trains were manufactured and delivered between 1996 and 2006, and again from 2012 to 2014 to expand service on the Gyeongbu Line and the Gyeongwon Line, and to replace older trains (1st and 2nd batch Class 1000 trains).