Following the derailment at Mossend (NCE last week), Railtrack tell us 'the rails had spread in excess of 60mm over the normal measurement of 1435mm. . . on a tight curve' and '. . . track spread cannot always be identified through routine visual inspections.'
Anyone with basic track knowledge will be aware that the gauge should be widened by design up to 19mm to ease the passage of wheels without generating excessive lateral forces and there are numerous tell tale signs which give early warning of an essentially progressive failure. Ask any patrolman.
Paul Leech firstname.lastname@example.org