PRIVATE CONTRACTORS brought in this week to upgrade London's Underground could already face a huge bill for repairing defective Central Line trains.
London Underground chief engineer Keith Beattie said that the Metronet consortium might have to repair defects discovered by engineers investigating the derailment at Chancery Lane in January.
Metronet comprises Balfour Beatty, Thames Water, Atkins, Bombardier and Seeboard. It became responsible for the upgrade and maintenance of the Central Line last Friday when it signed a 30 year partprivatisation deal (see box).
Investigations into why a motor fell off a train causing it to derail at Chancery Lane have revealed several inherent faults with the drive systems in the '92 stock' trains.
LUL chief engineer Keith Beattie said that LUL and Metronet are carrying out a joint design review of the drive system to see if the trains need substantial repair work.
But Beattie said that if the work is needed, Metronet should foot the bill as taking trains out for repairs would affect the reliability of the Central Line service.
Under the part privatisation contract Metronet is responsible for ensuring that services are maintained to agreed levels.
'In my view Metronet has priced for the risk of latent defects, ' said Beattie.
'Clearly we will have to talk to Metronet about the financial implications, ' he said.
Beattie said that LUL had almost completed repairs to the trains to ensure that motors cannot detach from the trains in future.
This has included fitting stronger bolts to fix the motors to the bogeys and improving safety brackets to catch motors if they become detached.
LUL is carrying out and paying for the work because it is safety related and because the accident happened before Metronet signed the part-privatisation deal.
Beattie said this week that the inherent defects included problems with the friction pads between the motor bolts and bogeys and gearboxes.
The friction pads have become covered in a mysterious pitting, which is reducing the friction between the pads.
This may help the motor bolts loosen with train movement.
Gearbox systems mounted on the bogeys are also prone to vibration damage as wheels wear down.
The review may show that the whole drive system needs changing, said Beattie.
He added that if the trains are found not to meet original design specifications LUL may also have a compensation claim against Bombardier, which supplied the original 92 stock trains.
Bombardier said this week that it felt that design faults with the stock were no longer its responsibility. 'London Underground carried out full rigorous tests when they accepted the stock, ' said Bombardier services president Andrew Lezala.