The companies had pleaded guilty to breaking health and safety laws in November 2002.

The Old Bailey was told that 450 passengers were on board the Swansea to Paddington service as the wheels of one of the eight coaches came off the track.

The 8.05am train was travelling at 120mph through Southall station in west London.

The train went on for a further two miles before coming to a halt.

"It must have been exceptionally frightening for the 450 fare-paying passengers, not to mention the frustrating inconvenience of a two-and-a-half- hour evacuation," said Judge Richard Hone.

An official report into the accident had concluded that it was "an unlucky and unpredictable event".

Network Rail was fined £200,000 and Amey £300,000. They were ordered to pay costs.

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Network Rail, Amey Fined 500,000 Pounds for U.K. Derailment

Bloomberg: Sept. 12
By Megan Murphy

Network Rail Ltd., the operator of Britain's stations and track, and rail services firm Amey Plc were fined a total of 500,000 pounds ($937,000) over the derailment of a high-speed train in west London in 2002.

None of the train's 450 passengers were injured in the accident, which was triggered by a cracked plate on the rails. Network Rail and Amey pleaded guilty in April to one count of breaching healthy and safety laws.

Judge Robert Hone QC today fined Amey 300,000 pounds and Network Rail 200,000 pounds for failing to properly maintain the track. The total penalty is less than 5 percent of the 11 million- pound fine handed down for a 2000 derailment near Hatfield, England, in which four people were killed.

"The culpability which I have identified is certainly not the worst of its kind,'' Judge Hone said at a brief sentencing hearing at London's Central Criminal Court. "It does, however, illustrate that what might be considered quite small failures can aggregate into something much more serious.''

The train was traveling between Swansea, in Wales, and London's Paddington station at around 120 miles per hour when the derailment occurred, according to documents submitted to the court. The train's driver and manager both suffered severe stress in the aftermath of the accident, while its passengers were subjected to the "frustrating inconvenience'' of a 2 1/2 hour evacuation, Hone said.

Amey, based in London, was acquired by Spain's Grupo Ferrovial SA in 2003 for around 231 million pounds. Network Rail, which took over Britain's network of 34,000 kilometers (21,000 miles) of rail in 2002 after the collapse of Railtrack, has ceased subcontracting track maintenance to other companies.