Complex sentence: A block is placed across the tracks at the 590 kilometre mark (a short distance on from Dumaresq), and north of Glen Innes the line, particularly its bridges, has fallen into disrepair.
Split into simpler sentences: A block is placed across the tracks a short distance from Dumaresq, at the 590 kilometre mark. North of Glen Innes the line, and particularly its bridges, have fallen into disrepair.