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Small openings and narrow trenches

In small openings and narrow trenches, the following options are permitted regardless of whether the existing sub-base is a bound material:
  1. An HBM sub-base of 100 mm minimum thickness; or
  2. A 50/20 HRABC or 20 mm DBC material of minimum 40 mm thickness, laid in place of the granular sub-base; or
  3. Three equal layers of 15/10 HRASC, 6 mm DSC or 6 mm SMA material laid to a total thickness of 100 mm, as a combined sub-base, binder course and surface course.