Andrew Agathangelou – Diales Delay Expert explores the various paths open to delay analysts.
In February 2017, China opened the longest elevated bike path in the world in a city in South-East China. The five-mile long, 16-feet wide bicycle-only pathway – dubbed ‘the winding viaduct’ – has been built in the city of Xiamen. It takes a very meandering path between the start and end points, in order to achieve the status of the longest elevated bike path in the world.
In the world of delay analysis, the use of retrospective techniques, which require the delay analyst to establish ‘longest path’ through the works, is becoming very common. In simple terms, the longest path can be thought of as the longest chain of connected construction activities which determine the overall completion date of the works. In this respect, the ‘longest path’ can also be considered to be the critical path, a term familiar with those who work in this field. It is generally accepted that for an event to cause delay, it must either lie upon the critical (longest) path, or directly impact another activity which lies upon the critical path.
A common feature of the various techniques used to establish the longest path through the works retrospectively, after the works are complete, is the ability to establish the path manually, by visual examination of the as-built programme, as opposed to using programme software.
The longest path between the start and finish points, on the as-built programme, is established by first examining the actual finish date and then determining which construction activities were directly connected to the completion date, or which activities were completed on the actual completion date.
The analyst then works backwards to the actual start date, examining numerous links in the chain of construction activities occurring between those dates in order to establish which took the longest. Thereby ultimately determining the actual completion date. This ‘longest path’ is often referred to as the ‘as-built critical path’.
This approach is becoming more common with delay analysts. Some experts deliberately avoid the use of programme software on the basis it is sometimes seen as a ‘dark art’. Disputes involving expert delay evidence are often distracted and undermined by arguments over the robustness of the baseline programme; whether it is correctly logic linked or whether it accurately reflects the true scope or sequence of the works. Perhaps this is due to results and analysis being overly reliant on an answer produced by programme software rather than by a detailed review combined with common sense and experience.
Like the elevated bike path in Xiamen, it remains to be seen whether manual inspection and establishment of the ‘longest path’ will catch on or become a passing fad. For those delay experts who refuse to use any kind of programme software, it remains the only method of establishing a critical path of some kind, essential to demonstrating that a delay to completion has occurred.
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