Concurrency – A Call for Pragmatism?

Concurrency (or concurrent delay) is an issue that those involved in construction disputes love to debate. A quick search online reveals a vast amount of ink which has been spent debating the various approaches to analysis and assessment of concurrent delays on a construction project. 

From at least 1997 onwards, the term “Concurrent Delay” has appeared in court case reports. One of the earliest is that of Norwest Holst v Cooperative Wholesale Society – ([1997] EWHC Technology 356). There have been many discussions over the course of the last 25 years or more about how concurrent delay should be addressed, its analysis, and indeed, whether it exists at all. 

However, is concurrent delay almost inevitable on larger projects? And in any case, might a more pragmatic approach be helpful in reducing the likelihood of such arguments arising?

How it works – How is Concurrency Defined and Assessed?

The English judge and barrister, John Marrin QC (as he was then), stated in a paper for the Society of Construction Law in 2002:

“Since at least the 1980s, it has commonly been suggested that the correct approach to the matter of causation in determining contractors’ claims is to apply what is called the ‘dominant cause approach’.  On this approach, the architect is required to choose between competing causes of delay according to which is ‘dominant’ or ‘predominant’.”

This is perhaps a common-sense approach in its purest sense. It is also arguably, reflective of its time. Prior to the late 1990s, computer technology was such that detailed electronic analyses of delay were less common.

As Pickavance notes, before personal computers arrived, detailed critical path analyses and scheduling required a lot of resourcing and time. Such requirements would render analysis almost impossible at any degree of scale. Developments in technology over the past 20 years or so have led to an explosion in the use of Critical Path Methods of analysis for delay. Methods that previously would not have been available.

Is Technology the Problem?

However, it is also noted by Pickavance that this explosion in cheap technology has led to:

“nothing more than drawing a pretty picture that was created without any thought to project scope and without any consideration for the logical dependencies between activities”[1].

Has the very thing that allowed an increase in analysis in part caused some of the problems? The cheap and accessible tech might be making disputes more complex and more difficult to resolve. The question then being whether the disputes should, in fact, be easier to resolve?   

Marrin also sought to define concurrent delay in his paper. It is this definition which has held ever since:

“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 approximately equal causative potency.”

The History of Concurrency in Courts

Case law on the subject ranges in its views. Some have suggested that the concept of concurrent delay is non-existent or impossible to prove. Others have advocated an award on the basis of the ‘first to reach it’, to an apportionment.

There have been several supposed ‘orthodox’ approaches to the analysis of concurrent delay. In early cases, it was suggested concurrency should be simple to identify and deal with, where it arises. However, as Pickavance notes, “as a result of the various attempts of tribunals and courts to expand [a] simple compensation-related formula into ever more complicated time-related scenarios, that simple thesis has become more difficult to follow”[2].

In the case of Henry Boot and Malmaison, the approach was that if it’s permitted in the contract, you have entitlement to an extension of time. Or more clearly: “… if there are two concurrent causes of delay, one of which is a relevant event, and the other is not, then the contractor is entitled to an extension of time for the period of delay caused by the relevant event notwithstanding the concurrent effect of the other event.”[3]

More Recent Approaches

More recently there have been attempts to contractually remove concurrency from contracts. In the case of North Midland and Cyden, the approach was along the following lines… If there is employer and contractor delay that run concurrently, then you do not get an extension of time as the contractor.

Interestingly, there are firms who actively promote the contractual deletion of disputes over concurrent delay. In researching this article, we have encountered at least one firm saying employers should ensure contracts are clear. They note the need to add clauses stating that in the event of concurrent delay where employer and contractor coincide, the contractor will not receive an extension of time.

Claims for concurrency are almost inevitable, but is concurrency actually inevitable?

The longer a project runs and the more complex a project gets, is it more likely that at some point two delays will arise concurrently?

Projects such as sports stadia, oil and gas plants, major infrastructure and tall buildings have so many things going on all at once. It is difficult to anticipate a scenario where multiple elements are not delayed at the same time. Equally it is likely that on such a project concurrent delay is inevitable.

Projects are more likely to experience and suffer from extraneous issues the longer they run (or the longer they are delayed).

Bad Faith and Examples…

By way of example, experiencing labour and material shortages outside of the original period is often an ‘un-planned for’ risk that was not in the contemplation of the tendering party.

The issue of visas for labour resources and/or commissioning engineers may expire when the construction period extends. This in turn may cause a new resource issue that may become concurrent.

Of greater concern are delays caused by matters that one party had greater control and knowledge of. For example, consider the employer who advises the contractor that the design process is nearing completion and will be sufficiently advanced prior to the trade contract starting its works. The contractor may then have to ‘live with’ a design process which causes delay to its works. The employer (finding culpable issues) then may state this is a period of concurrent delay.

In what could have been a straight-forward correction to the programme and price by ensuring a design freeze, the contractor/subcontractor may find itself ‘financing’ a period of time on the project.

It would be unreasonable for a party to rely on a concurrency argument when it was aware of impending delays it intended to negate by way of concurrency arguments. Particularly if it planned those arguments with another party who found itself on the project for longer than planned through no real fault of its own. That would not be good faith.

Does it Even Exist?

In reality, it is almost impossible for actual concurrent delay to exist. Time, as another expert observed (Gainsbury, 2018) is “infinitely divisible”. So at some point there will have been a time where one delay occurred before the other. Even if that is only by minutes or indeed hours. So true concurrent delay is therefore unlikely to ever arise. But that doesn’t stop people attempting to analyse it, and many hours of consultancy time being spent in that analysis.

All that remains is to take a sensible approach to tackling it. The concept referred to in our article for CIArb discusses the nature of good faith. If parties were to work together in Good Faith, issues might be dealt with amicably, without need for recourse to the legal process.

Above all, as always with construction projects and disputes, the absolute need for good, accurate records is key to ensuring resolution of disputes. If delays arise, the accurate demonstration of the link between the cause and resulting effect will be critical. Detailed and often academic arguments over concurrency might well be avoided if correct contemporaneous records are kept on a project.


[1] Pickavance, Delay & Disruption in Construction Contracts 4th Ed, 2010, P339 

[2] Pickavance, Delay & Disruption in Construction Contracts 4th Ed, 2010, p.1037 

[3] Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd(1999) 70 Con LR 33)