Current speed record for trains is held by French TGV bullet train. It reached the speed of 584km per hour (363 mph) and then braked for 16 kilometers (9.9 miles) before it managed to stop.
Source: Train History
Photo by Taxiarchos228 – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=11836501
