ABOARD TRAIN V150, France - The speedometer climbed higher and higher - and so did my heart rate. Inside the last of three double-decker cars sandwiched between two engines, those of us 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, 550.

In this aerial photo jointly released on Tuesday, April 3, 2007 by the French railway company SNCF, Alstom Transport and the Reseau Ferre de France (RFF), or French Railway Infrastructure, the high-speed French train, with a souped-up engine and wheels, speeds on its way to break the world speed record for conventional rail trains in eastern France, Tuesday, April 3, 2007, reaching 574.8 kph (357.2 mph). [AP]

Looking out the windows, the French countryside became a green blur.

Then the magic number appeared: 574.8 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.

The air pressure made my ears ache.

Frankly, I was happy when it was over - and not because the journey quite literally ended in Champagne.

The chrome and black V150 looked majestic as its engines hummed on the platform near the town of Preny, east of Paris, before Tuesday's record run.

For its mission to break the speed record, 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 V150 was equipped with larger wheels than the normal French TGV - or "train a grande vitesse" - to cover more ground with each rotation, said Alain Cuccaroni, in charge of the technical aspects of testing. French TGVs normally cruise at about 185 mph.

But this was more than a stunt. The demonstration was meant to showcase technology that France wants to sell to multibillion-dollar overseas markets such as China.

In Preny, tension aboard the V150 mounted as the doors closed - it was too late to turn back. Alstom Transports, which built the train, transformed the passenger cars into a laboratory for the event so technicians could gather data to improve future TGVs.

As the train quickly gathered speed on a new rail line to open in June between Paris and Strasbourg, we watched a mini-pendulum suspended by reporters to gauge the train's sway. Journalists were not buckled in, but were told not to move because we might interfere with live television broadcasts from the train.

When we hit 242 mph, it felt like an airplane taking off. The pressure sent pains through my ears as we rocketed past applauding and cheering crowds on bridges and adjacent country roads.

Outside, the train roared by like a jet, sparks spit from the overhead power lines and a trail of dust sprayed out behind.

Inside, the pendulum swung widely, and the train shook and roared.

We soon broke the 1990 record of 320.2 mph - also set by a French train.

Then, near the village of Le Chemin, we hit the record of 357.2 mph. The train was speeding far faster than a passenger jet taking off. In fact, we kept up with planes flying overhead taking photos.

I thought we were about to derail.

Only 15 minutes had passed since we departed.

Officials aboard applauded, and the train immediately slowed. In comparison to its record, its cruising speed of around 190 mph felt escargot-paced.

"There are about 10,000 engineers who would want to be in my place," said the operator, Eric Pieczac. "It makes me very happy, a mixed feeling of pride and honor to be able to reach this speed."

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 Arcadis.

China plans to build more than 7,500 miles of high-speed railways in coming years at a cost of more than $250 billion. Construction is to start this year on a high-speed line between Beijing and Shanghai cutting travel time from nine hours to five.

France competes with Germany and with Japan for contracts. Earlier Tuesday, Transport Minister Dominique Perben received California Assembly Speaker Fabian Nunez. The state is studying prospects for a high-speed line from Sacramento to San Diego, via San Francisco and Los Angeles.

When we reached our destination at Champagne-Ardennes train station, people cracked open bottles of champagne - slicing the necks with swords, a French tradition.

Technicians on the train had "French excellence" emblazoned on their T-shirts, and President Jacques Chirac agreed, praising the record as "a magnificent demonstration of France's formidable capacities in research and innovation."

A few other people on the train described it as a "nice" ride - but most of us were glad to get off.

The whole experience left my knees shaky.

Then, the final flourish: we were given a survivors' certificate.

"Ingrid Rousseau participated in a journey at very high speed," it read. "This train established a new world speed record on rails April 3, 2007: 574.8 km/h."