Concurrency has been bugging me for years. Ever since I looked at actual bars on competing critical paths on the Ground Transportation Centre dispute between HKAA v MTRC. 

​

Despite many delay analysis text providing many different views on how concurrency should be dealt with, there is still no prescribed method to make its determination. There are many if's and but's to be considered before setting out parameters to place rules for determining concurrency. However, whilst there are many permutations that can be made, if parties can agree to a pre-prescribed methodology within their contracts before a contract commences, a great deal of the confusion and argument can be removed and then concurrency can therefore be reasonably and persuasively defined with a degree of certainty all can agree upon.

​

I have read many text on concurrency  and now consider that "parameters" need to be set out with respect to EOT clauses within contracts, before any determination is embarked upon. If so, a more certain  determination can be made. 

​

In general a good understanding of the following would help:

​

1. An understanding of what the difference is between an as-built critical path determined from a dynamic contemporaneous analysis as opposed to one determined via an as-planned v as-built determination and, from reference to the contract, which one should be used. 

2. The difference in what is meant by a literal approach as opposed to a functional approach to the impact of the competing events on an activity that resides on the as-built critical path where they both cause a delay to the progress of the works, simultaneously, which results in a critical concurrent delayed effect to the date for completion. 

3. What is meant by dominant cause theory, however, this is not so much about delay analysis, it is more to do with liability for a competing event and was that event a dominant cause of not (effective cause). If one is more effective or dominant than the other competing event then concurrency does not exist. Therefore one has to be able to distinguish, as to what is said to be of competing events, is that are they of equal causative potency. This I suggest, is probably the most difficult to define and maybe not one for the delay analyst (it certainly would not be for the delay expert to decide in a formal dispute, he/she could only say competing events were concurrent and for how long they were concurrent and what delayed effect they caused to the date for completion). 

​

I have found the following text helpful in my understanding of concurrency and how it should be determined: 

​

​

​

​