Concurrent delays are the subject of much debate and, it must be said, a great deal of misunderstanding. A simple approach is to say that it is when two or more things happen at the same time and delaythe completion date of a particular contract. However, that is not the whole story: there are two kinds of concurrent delays. There are delays which occur at the same time to two different activities and there are the delays which occur at the same time to the same activity. It is the latter which causes the problems.
If delays act on different activities, it is easy to deal with the situation by inputting the delays, one at a time, into the contractor’s programme and noting the effect. This can be done using computer software. It is only the delays which are grounds for extension of time which must be entered. Contractor’s culpable delays are ignored. One court commented that:
. . . it is agreed that 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.
This must be a correct view where the two concurrent delays operate on different activities and, as noted earlier, computer analysis easily deals with this situation by ignoring all delays which are not relevant events.
True concurrency is when the causes of delay operate at the same time on the same activity. To take a simple example, a contractor may have difficulty in obtaining labour to lay paving, but the architect may also be delayed in providing the necessary drawings showing the layout of the paving. The courts have not adopted an entirely consistent approach. Indeed, the guidance one might expect from the courts has not been very helpful. Sometimes, what is known as the ‘dominant cause’ approach has been advocated. One court has asked ‘. . . what was the effective and predominant cause of the accident that happened, whatever the nature of the accident may be’. It has been said that the test is that of the ordinary bystander. Yet again, a court has suggested that the architect might simply apportion the responsibility for delay between two causes. As to how that is to be done, the court concluded that the basis must be fair and reasonable. A sensible view of concurrency was given in a later case:
However, it is, I think, necessary to be clear what one means by events operating concurrently. It does not mean, in my judgment, a situation in which, work already being delayed, let it be supposed, because the contractor has had difficulty in obtaining sufficient labour, an event occurs which is a Relevant Event and which, had the contractor not been delayed, would have caused him to be delayed, but which in fact, by reason of the existing delay, made no difference. In such a situation although there is a Relevant Event, ‘the completion of the Works is [not] likely to be delayed thereby beyond the Completion Date.’ The Relevant Event simply has no effect upon the completion date.
True concurrency is fortunately rare. In most instances, where delays occur to the same activity, they are consecutive.