The railroads use a portable cut off saw with an abrasive blade to cut track to final dimensions prior to splicing. Then use a gas powered annular cutter for the bolt holes.
Since this is used track I would think the top of the track will be work hardened. you just got to get thru that fop layer.
I worked in a foundry that used track for stock to cast brake rotors, they would cut the first couple of inches from the top of the track down with OA, then lift the piece up about 10 feet and drop it, snapped in half.