DOnt know what TRT is,they place new 60 kg rails on sides of of existing tracks and clamp them parallely,they remove the ballast manually.They bring 10 meters of clamped sleepers and rails on a open goods rake,they clt 10 m of existing track with gass cutters,a machine comes on goods open rake which runs on parallel clamped rails,hools up the cut piece and unloads and puts back new sleepers clamped by rails.when they are done for 100+ meters they unclamp 10 meters pieces of rails and clamp the 60 kg rails which was clamped parallely early on.