On Tuesday, NS's Lehigh Line had a departure from the 'normal' trains I am accustom to seeing along this stretch of track. It was the Federal Railway Administration train, NS symbol 901, consisting of NS 5175 (ex-SOU 5175; GP38-2), NS 5609 (ex-NW 4138; GP38-2), DOTX 218 and DOTX 220 passing by LEHL MP 40 around 1 PM. The DOTX 218 Entered service in 2004 and operates in self-propelled and towed mode, is equipped with a track geometry measurement system to measure gauge, alignment and track surface. It has a Gage Restraint Measurement System (GRMS), utilizes a deployable fifth axle to apply lateral and vertical loads to the rail and then take measurements of the impact to the rail from the forces. DOTX 218 is also equipped with a differential global positional system to provide high accuracy GPS coordinates to each foot of track surveyed. DOTX 220 was built in 2007 and is equipped with a full suite of track geometry measurement and mapping systems, allowing it to take real time track geomertry, laser-measured gauge, profile and ride quality measurements and record the data in its own systems at extremely high speeds. The car has crew seating for up to 16 to 20 in the inspection gallery at the B-end and 4 in a technicians' station at mid-car. It is also equipped with a small galley, ample storage, and an ADA-compliant restroom.