If reinstatement materials are used that require compaction e.g. granular sub-base, HRA, etc., the width of trimback required will be the width of the frame base plus the width of the compaction tool sole plate plus 30 mm.
Reinstatement materials that do not require compaction
If reinstatement materials are used that do not require compaction e.g. concrete or PMMA, then a minimum width of trimback will be required to install the apparatus and ensure depth of penetration of the reinstatement material. For roads this will be a minimum of 50 mm in excess of the flange width. For footways, footpaths and cycle tracks the minimum width of trimback is the width of the frame.