LONDON Underground infrastructure companies Tube Lines and Metronet have used shutdowns on sections of the network in the wake of the July 7 bombings to speed up infrastructure improvements.
Metronet has carried out extra track and signalling work on the Circle Line, which has been closed for three weeks since the terrorist outrages that killed 56 people.
Heavy maintenance work was carried out on a stretch of the line called Craven Hill Gardens between Paddington and Bayswater.
Improvement work on the track and signalling was also completed between High Street Kensington and the Edgware Road bomb site.
Tube Lines, which is responsible for the Jubilee, Northern and Piccadilly Lines, has accelerated non-track maintenance and upgrades at Caledonian Road, Turnpike Lane and Manor House stations on the northern stretch of the Piccadilly Line where station modernisation work was under way.
The route is closed for 16 stops - between Arnos Grove towards the northern end of the line and Hyde Park Corner in central London - which has allowed the work to go ahead.
Work on the platforms could not be carried out because of concerns that any debris could contaminate the King's Cross bomb investigation crime scene where 26 people were killed.
Extra unscheduled improvements have also gone ahead at Bounds Green in north London while the station is closed - work which could only usually be carried out at night during 'engineering hours' A Tube Lines spokeswoman said: 'We have made the most of the closures and got a significant amount of work done.'
The infrastructure company has also carried out work on points at various stages on the line but it cannot carry out any extra track work as the firm is on standby to go into King's Cross when the police hand the site back to Transport for London.
The spokeswoman said: 'We need to be ready to go at a moments notice.'
Tube Lines has drawn up a detailed works programme and staff timetabling system to allow it to survey, test, clear and repair the tunnel and track at King's Cross.
nA team of 200 Metronet engineers worked in shifts around the clock to repair the bomb damage at Aldgate station in east London, which opened on Monday morning.
Ultrasonic testing revealed major damage to cable, signalling, power and communications in the tunnel. London Underground ran test trains through the area before it was reopened.
Metronet is responsible for upgrading two thirds of the Tube network and expects to complete work at Edgware Road in west London by next week.
Anti-terrorist police handed control of the Edgware Road site back to LU nine days ago.