A breakdown in the computer system that coordinates labour supply caused chaos on rail construction sites last week.
Computers failed at the National Control Centre for the Sentinel registration a week last Friday and were still down this week as NCE went to press.
All rail personnel have to be Sentinel accredited to show they have received sufficient training, a unique system in the construction industry. But the breakdown in the system meant that sites were unable to check workers' cards leading in some cases to qualified staff being unable to gain access to sites.
As a contingency, Railtrack increased staff at the centre and cards are being issued manually.