ABOARD TRAIN V150, France — The speedometer climbed higher and higher — and so did the heart rate of passengers.

Inside the last of three double-decker cars sandwiched between two engines, those aboard the French bullet train trying to set the speed record on conventional rails watched the digital numbers flash on a screen in kilometers per hour: 400, 450, 500, 545.

The French countryside became a green blur.

Then the magic number appeared: 547.8 kph, or 357.2 mph — faster than any humans had ever traveled in a train on rails. As fast as an airplane, but on the ground.

For its mission to break the speed record Tuesday, the train was modified with a 25,000-horsepower engine, and adjustments also were made to the track, notably the banking on turns. The rails were treated so the wheels could make perfect contact, and electrical power in the overhead cable was increased from 25,000 volts to 31,000 volts.

The demonstration was meant to showcase technology that France wants to sell to multibillion-dollar overseas markets such as China.

Alstom Transports President Philippe Mellier said before the test that it would try to outdo the record of 361 mph set in 2003 by Japan's non-conventional magnetically levitated train. But in the end, the French train fell just 4 mph short.

Pierre-Louis Rochet, former head of French state-run rail network SNCF's international division, said this may be as fast as it gets on standard rails.

"There is no interest" in going faster, since after that "the costs will increase too much," said Rochet, now rail director for international engineering firm Arcadias.