CONTRACTORS TUBE Lines and Metronet this week commissioned a modified Land Rover to detect rail defects on the Underground.
The move is part of a £3M programme to fully automate the Tube's network condition surveys.
The vehicle is fitted with additional rail wheels to run on the track.
It will operate on the sub-surface lines, but not the deep Tube lines where exhaust fumes from the diesel engine would be dangerous.
It tows a trolley fitted with ultrasonic detection equipment to identify track irregularities.
The vehicle is provided by Sperry Rail International.
Within six to 12 months the vehicle will be replaced with the new Track Recording Vehicle (TRV), which will improve survey speed further as it will be able run 24 hours a day across the entire network.
This will increase the coverage of Tube Lines and Metronet survey teams tenfold.
'This is a step change. We will go from surveying plain line every six months and joints every two to three to surveying the entire LU network in a month, ' said Tube Lines infrastructure manager Stuart Mills.
Currently, all rail flaw detection on the Underground is carried out manually using hand-held ultrasonic detection devices. A team of three or four workers can inspect up to 5km of rail in a four hour night shift.
The new ultrasonic Land Rover travels at up to 10mph and can cover 20km during an 'engineering hours' shift.
But limited access points restrict its use to the open track sections.
The improved ultrasonic testing regime has been introduced following the Hammersmith derailment last October (NCE 23 October 2003).
Investigators concluded that a broken rail caused the derailment but said visual inspection and ultrasonic testing practices preceding the incident would not have picked up the defect.