London Underground (LU)'s Central Line has fully reopened following Tuesday's train derailment.
The train was approaching White City when it came off the tracks
No-one was hurt, but 150 passengers were led to safety after the accident near White City station in west London.
The Central Line was shut for months in 2003 while trains were taken out of service for checks, after one hit a wall at Chancery Lane station.
LU says the initial investigation into Tuesday's derailment will focus on the track, not the rolling stock.
Metronet, which maintains the track, said it would be looking into its work amid reports maintenance had only been carried out the night before.
The westbound line had been suspended between North Acton and Marble Arch following the accident at 1227 BST.
A Metronet spokesman said: "We don't know if our recent work and the derailment are connected and we are looking into the work we've been doing."
Tube derailments in 2003
25 Jan: Chancery Lane crash
17 Oct: Minor derailment at Hammersmith
19 Oct: Seven injured at Camden Town
The maintenance work was being carried out on the track on Monday night in an attempt to remove the 20mph speed limit, which had been in place on the section of track since April last year.
Metronet is responsible for maintenance on two thirds of the Tube.
Bob Crow, general secretary of the Rail, Maritime and Transport union (RMT), said it was lucky the speed restriction was in place.
He said: "However, this particular speed restriction has been in place for months, and serious questions need to be asked about why remedial work has not been carried
out by the privatised infrastructure companies now responsible for maintaining the underground."
An LU spokesman said the rolling stock was unlikely to have caused the derailment.
He said: "The initial investigation has focused on the track. The derailment occurred at a set of points that were immobilised while they were awaiting further track work."
In January 2003, a Central Line train became derailed and hit a wall at Chancery Lane station in central London, injuring 32 people.
And seven people were hurt in October when a Northern Line train was derailed at Camden Town, in north London.
That incident occurred two days after a Piccadilly Line train became derailed in west London.