Concurrent Delay in Australia: Why Contract Wording and Causation Matter

Concurrent delay is one of the more complex issues encountered in construction contract administration and extension of time assessments.

It arises where separate delay events overlap and potentially affect the same period of project completion.

The assessment becomes particularly challenging where one event falls within the principal’s risk and another falls within the contractor’s risk.

However, the existence of overlapping events does not necessarily establish true concurrent delay.

The critical question is whether the events independently affected the project’s completion, having regard to the relevant programme, circumstances and contractual provisions.

The treatment of concurrent delay can differ between jurisdictions and contractual arrangements.

The Malmaison Approach

English construction law has developed an approach commonly associated with Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd.

Under this approach, where an employer-risk event is an effective cause of delay to completion, a contractor may be entitled to an extension of time notwithstanding a concurrent contractor-risk event.

The distinction between entitlement to time and entitlement to delay-related costs remains important.

An extension of time does not automatically establish an entitlement to prolongation costs.

The treatment of concurrency under English law has also been considered in Walter Lilly & Co Ltd v Mackay and discussed in the Society of Construction Law’s Delay and Disruption Protocol.

These authorities and guidance provide useful context, but their application to an Australian project should not be assumed without examining the governing law and contractual provisions.

Australian Approach: Contractual Entitlement and Causation

Australian law does not provide a single, universally applicable approach to concurrent delay.

The assessment depends on the contractual provisions governing extensions of time, the circumstances of the overlapping events and the evidence establishing their effect on project completion.

A first-in-time analysis may be relevant where an earlier delay has already affected the critical path.

However, the timing of an event alone does not necessarily determine entitlement.

The contractual risk allocation and actual causative effect of each delay must be considered.

Australian authorities, including Australian Development Corp Pty Ltd v White Constructions (ACT) Pty Ltd, form part of the discussion concerning causation and delay entitlement.

These authorities should be considered in their specific factual and contractual contexts rather than treated as establishing a universal first-in-time rule.

The Importance of Evidence

The NSW Supreme Court’s decision in White Constructions Pty Ltd v PBS Holdings Pty Ltd highlights the importance of establishing delay causation through appropriate evidence.

The case illustrates that the selection of a recognised delay analysis methodology does not, by itself, establish the accuracy of the resulting conclusions.

The methodology must be appropriate to the circumstances and supported by reliable project information.

In practice, a defensible concurrent delay assessment may require consideration of the accepted programme, critical path, progress records, contemporaneous correspondence and the actual effect of relevant events.

An analysis that identifies overlapping activities without demonstrating their effect on completion may be insufficient to establish the claimed entitlement.

Contractual Apportionment

Australian Standard contracts may contain express provisions addressing concurrent delay.

For example, clause 34.4 of AS 4000-1997 and AS 4902-2000 contemplates apportionment where qualifying and non-qualifying causes of delay overlap.

However, the application of these provisions depends on the contract in force, including any amendments or special conditions.

Other contracts may adopt different approaches to concurrent delay, including specific exclusions, qualifications or alternative allocation mechanisms.

The contractual position should therefore be established before undertaking the substantive assessment.

For contractors, this is important when preparing extension of time claims and substantiating the effect of delay events.

For principals and contract administrators, it is equally important when evaluating entitlement, determining extensions of time and managing exposure to time-related claims.

The Commercial Implication

Concurrent delay should not be assessed by applying a single legal principle or programming methodology in isolation.

The starting point is the contract, followed by a detailed assessment of the relevant delay events, their impact on the critical path and the evidence supporting the claimed entitlement.

For principals and contractors alike, understanding how the contract allocates concurrent delay risk is essential to maintaining a defensible commercial position and avoiding disputes over time-related entitlements.