A final report into the derailment will be published later this month

The Piccadilly train became derailed shortly after leaving Hammersmith Station at 2111 on 17 October heading for Baron's Court.

Nobody was injured but all the wheels on the last carriage left the tracks, causing damage to the rails and sleepers.

A report released on Friday said the equipment the area of the derailment was "in a poor condition and had been so for many years".

But it said improved checks and track renewal plans were now being put in place by Metronet - the company responsible for the maintenance of the Piccadilly line track at Hammersmith.

'Safety is priority'

Two days after the west London incident seven people were taken to hospital following the derailment of a Northern line train at Camden Town station.

The report said: "It is clearly evident that the [Hammersmith] derailment occurred because of a broken rail.

"However, it is clear that neither visual inspections by patrollers, nor the present method of ultrasonic testing would have, and will not provide reliable identification of this type of initiating rail defect."

Maintenance standards

London Underground (LU) managing director Tim O'Toole said: "Safety is my top priority. It is vital that we understand the cause of the derailment at Hammersmith and take whatever action is necessary to avoid such incidents in future.

"London Underground and Metronet are already looking at Tube maintenance standards and practices, including the frequency and technology of ultrasonic testing, to detect such rail defects.

"We will be publishing our final conclusions and recommendations later this month, which we will of course share with Tube passengers and staff."

The report was compiled by an investigation team consisting of LU and Metronet Rail staff, as well as health and safety representatives from the RMT, Aslef and TSSA unions.