FIDIC

Acceleration Under FIDIC — Directed and Constructive Claims

When project delay requires recovery, the cost of acceleration can be enormous. The contractor’s entitlement depends on whether the acceleration was formally instructed or was a response to the employer’s wrongful refusal of an extension of time.

6 min read · Updated 23/05/2026

In this article

1. Directed Acceleration — Instruction and Valuation
2. Acceleration Costs — What Is Recoverable
3. Constructive Acceleration — The Legal Doctrine
4. The Written Protest Requirement
5. Quantifying Acceleration Costs
6. Settlement and Valuation Disputes

Key takeaway

Directed acceleration must be instructed in writing and priced before execution. Constructive acceleration requires a contemporaneous written protest of the wrongful EOT refusal before commencing acceleration measures. Without the written protest, the claim collapses — regardless of the merit of the underlying wrongful refusal.

1. Directed Acceleration — Instruction and Valuation

Directed acceleration is the straightforward case: the employer, recognising that the project is behind schedule, instructs the contractor to accelerate — to complete earlier than the current planned date. This is a variation under FIDIC Clause 13 and must be valued as a variation, following the variation valuation procedure.

The instruction to accelerate should be in writing and should clearly state: the revised completion date required; the approval of the engineer or project manager; and an invitation to the contractor to submit a quotation for the acceleration costs.

The contractor should then submit a detailed acceleration quotation, breaking down the costs: additional labour (shift premiums, overtime, recruitment bonuses); additional plant (additional equipment, standby hire); additional supervision and management; and any other costs directly caused by the need to compress the schedule.

These costs should be priced and agreed before the contractor commits additional resources. An acceleration undertaken without a prior agreed price is risky — the eventual valuation may be disputed.

2. Acceleration Costs — What Is Recoverable

Acceleration costs cluster into several categories, each with different evidential requirements:

Costs that are NOT recoverable in acceleration include: costs already incurred in the original (unaccelerated) plan; costs that would have been incurred anyway; and savings that arise from the compression (e.g. shorter site establishment period).

3. Constructive Acceleration — The Legal Doctrine

Constructive acceleration arises where: the contractor is entitled to an extension of time for an employer-caused event; the employer wrongfully refuses or fails to grant that extension; the contractor, to avoid liquidated damages liability, accelerates the works to meet the original (now-impossible) completion date; and incurs costs in doing so.

The legal principle is established in Australian law (Turner Corporation v Co-ordinated Industries [1995]) and is recognised in English arbitration practice, particularly in international construction. The underlying logic is that the employer cannot both: (1) wrongfully refuse an extension of time and (2) benefit from the contractor’s consequential acceleration costs.

For constructive acceleration to succeed, the contractor must establish all four elements: entitlement to EOT; wrongful refusal; acceleration as a direct response; and costs incurred. Failure on any element defeats the claim.

4. The Written Protest Requirement

The most critical element in a constructive acceleration claim is the written protest. The moment the engineer refuses to grant an EOT (or the notice period for granting the EOT expires without action), the contractor must write to the engineer, stating:

• The contractor’s assertion that the event is a qualifying event entitling the contractor to an extension of time
• The contractor’s entitlement to the extension
• The engineer’s wrongful refusal to grant it
• The contractor’s intention to accelerate to meet the original completion date
• A reservation of the contractor’s right to recover all costs of acceleration

This notice must be served before the first acceleration measure is taken. If the contractor accelerates silently — without asserting its right to EOT or its protest at the refusal — the constructive acceleration claim collapses. The contractor cannot retrospectively assert that acceleration was undertaken in response to a wrongful refusal if there is no contemporaneous evidence of protest.

5. Quantifying Acceleration Costs

Acceleration costs must be separately coded and recorded during the acceleration period. The contractor should maintain cost records showing: labour hours worked and premium rates; plant hire and standby charges; supervision and management allocation to the acceleration period; and any other direct acceleration cost.

The evidentiary ideal is that these costs are segregated in the accounting system during the project — not reconstructed or analysed after completion. A contractor with acceleration cost codes running through the project accounting is far better positioned to substantiate a claim than a contractor attempting post-project analysis.

6. Settlement and Valuation Disputes

Where directed acceleration was instructed but the valuation is disputed, the variation pricing mechanism applies: if contract rates are available for the accelerated work, those rates apply (subject to adjustment for the difference in character); if no rates are available, fair valuation applies — what reasonable contractors would have charged for acceleration work of this character under these conditions.

Constructive acceleration valuation is typically subject to negotiation. The employer often challenges the necessity of the acceleration or the cost incurred. The contractor’s best protection is detailed contemporaneous cost records and a clear protest notice demonstrating the causal chain.

Acceleration Claims Under FIDIC

We advise on acceleration cost documentation, constructive acceleration strategy, and claim presentation. The written protest and cost records are the foundation of recovery.

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