Proposal to amend Annex 8, paragraph 2.8. to establish performance-based requirements ensuring continuous trailer immobilisation during service brake pressure depletion. The amendment requires that when a trailer is uncoupled and the park brake control is released, braking forces from combined service and parking braking systems shall hold the laden trailer at any time when service brake energy reservoir reduces from 850 kPa to 0 kPa, and that adequate overlap between service brake and spring brake functions be ensured so no loss of holding capability occurs during pressure depletion.