NETWORK Rail has banned Mowlem from bidding for any rail renewals jobs on the network.
The contractor will be barred until it can prove weaknesses found in its management have been corrected.
Mowlem will not have its rail renewals contract on the West Coast Main Line renewed following an investigation into substandard work on the route.
The contractor was suspended in January when Network Rail engineers found that clips securing the track to sleepers had come off on a section of its line near Bushey in Hertfordshire.
At the time Network Rail deemed the incident so serious that it suspended Mowlem from all renewals work.
An investigation was launched, during which time the WCML contract expired and Mowlem started implementing its improvement plan.
A Network Rail spokesman said: 'They will have to prove their management system can perform competently and safety before they can go for renewal work again.'
Mowlem's structures and other civils work for the not-for-dividend operator will be unaffected by any decision.
A source at one rival told Construction perform competently and safely before they can go for renewal work again.'
Mowlem's structures and other civils work for the notfor-dividend operator will be unaffected by any decision.
A source at one rival told Construction News:
'Mowlem is recognised as being very strong on structures and civils for Network Rail and not really so big on rail renewals.'
A Mowlem spokeswoman said: ' We are stronger in renewals outside the UK so it is a business we have experience in and we are keen to continue in.'
Following the investigation Network Rail has also tightened up its own procedures to ensure that a Network Rail engineer always signs off renewals work.
Mowlem finished its work in the early hours of January 10 before the Bushey incident and an engineer was not available to check it.
Mowlem fell £15.3 million into the red in 2004 after new boss Simon Vivian uncovered a number of writedowns and one-off charges following a review of the business.The news was shortly followed by a raft of redundancies in a bid to make annual cost savings of around £5 million.