Time Risk Allowance (TRA)

Time Risk Allowance (TRA) is a discrete duration added to specific activities in an NEC4 Accepted Programme to account for the risk of that activity taking longer than its most-likely duration. It is explicitly provided for under NEC4 Clause 31.2 and is intended to be a transparent representation of risk absorbed in the schedule — not hidden through constraint manipulation or duration padding.

TRA is distinct from float. Float emerges from the schedule logic as the difference between earliest and latest possible timing for non-critical activities; TRA is deliberately added duration reflecting specific risk judgement. The Contractor owns TRA under NEC4 — it is their provision for risks they have identified — but the Project Manager can see it in the Accepted Programme because it is itemised transparently rather than concealed.

The intent is to encourage honest risk management in the schedule. If the Contractor expects piling to take 40 days most-likely but sees material risk of slower progress, they should show 40 days of activity duration and 5 days of TRA rather than inflating the activity duration to 45 days. The transparent format makes the risk visible to the Project Manager and supports informed conversations about whether to mitigate, transfer or accept the risk — rather than everyone assuming the base duration is realistic when it actually contains hidden buffer.