As of Thursday, August 28, Amtrak officially began service on its new high-speed Acela trains, write Esther Fung and Taylor Umlauf for The Wall Street Journal.

The first five trains were launched as part of a $2.45 billion project to improve service along the key corridor from Washington to Boston.

While that is the goal, two of the new trains will be traveling slightly slower than their predecessors. For example, the new trains are schedule to complete the tip in about seven hours and five minutes, compared to about six hours and 56 minutes on the older Acela trains.

According to Amtrak, the limiting factor for the new trains’ speed is the railroad’s infrastructure. This includes the tracks, the switches, the overhead power system, and the signals.

While the newer Acela trains are able to reach a top speed of 160 mph, Amtrak’s old infrastructure means the new trains can only travel at top speed during specific parts of the trip.

Amtrak plans to gradually roll out 28 total NextGen Acela trains over the next two years. Meanwhile, the 15 older Acela trains that are still operational will be phased out over time.

Read more about Amtrak’s new NextGen Acela trains and what to expect as more of them roll out in The Wall Street Journal.

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