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CONCURRENT DELAY – CLEARING UP THE CONFUSION

Expert commentator John Marrin, in his 2003 paper, stated that definitions [of concurrent delay] are scarce since it is interpreted differently in different quarters.

The Oxford dictionary defines the word ‘concurrent’ as “occurring or operating simultaneously or side by side, or acting in conjunction.”

This definition suggests that concurrent delaying events must be both starting and completing at the same time. This, however, represents true concurrency, as identified by several commentators, including Winter et al. (2011, p. 4), true concurrency was hypothesised by LJ Dyson in Henry Boot v Malmaison Hotel (2002).^[1]

For events to actually start and finish simultaneously, and be truly concurrent, is rare and is not required when assessing whether the event caused concurrent delay. Events can actually overlap or be sequential, to be considered as a cause of concurrent delay. Each must merely be independently capable of causing a similar impact to completion.

This phenomenon is further explained by Marrin (2014, p. 2) and reflected in his 2002 definition:

‘..the expression “concurrent delay” is used to denote a period of project overrun which is caused by two or more effective causes of delay which are of approximate equal causative potency.’

Marrin (2014, p. 2) cites the case of Adyard Abu Dhabi v SD Marine^[2], as evidence that his definition is approved and refers to Furst and Ramsey (2016, note 3, para. 8-025) as evidence that it has been adopted.

 Marrin’s definition is consistent with the views of Curtis (2011, p. 6): 

 ..It might be possible to describe events as concurrent in the broad sense that they both possessed a causative influence upon some subsequent event, such as the completion of works, even though they did not overlap in time. 

O’Leary, D.J. (2014, p. 2) states that the following definition is often used by English lawyers:

  ‘A period of project overrun which is caused by two or more effective causes of delay which are of equal causative potency.’ 

Finally the Society of Construction Law (SCL) (2017, p. 31, paras. 10.7 to 10.11) concur that true concurrency is rare and that a more common usage of the term is when events occur at different times, but their effects are felt at the same time. A view consistent with Marrin.      

In America, Long (2016, p. 2 and p. 26) cites AACEI (2011, RP 29R-03) literal theory which distinguishes between literal, or true, concurrency and what it describes as functional concurrency, a phenomena aligned to Marrin’s definition. 

The following graphics, from Long (2016 p. 2 and p. 26), demonstrate true and functional concurrency. Graphics

^[1] Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd 70 Con       LR 32 (TCC);

^[2]Adyard Abu Dhabi v SD Marine Services [2011] EWHC 848 (Comm) (11 April 2011).