| Date | 24 May 2006 |
|
|
| Judgment | |
|
|
| The Issue | The collapsed as-built method of delay analysis requires a logic linked as-built programme to be established from which identified delays are then subtracted to establish a revised completion date as a consequence of their removal. |
|
|
| Implication |
This approach relies on as-built information and is therefore an approach that considers what actually happened rather than what might have happened and is often the appropriate method for retrospective delay analysis. |
printIn this the fourth in my series of articles on delay analysis, I consider the collapsed as-built method of delay analysis. This is an approach to modelling delay that relies upon the use of the as-built programme and is therefore generally limited to retrospective delay analysis. The method This is a popular CPM based method that in essence subtracts delays from the as-built programme and as a result determines the earliest date that the contractor could have completed, but for the delay events relied upon. This requires first the identification of the as-built dates for the construction activities in sufficient detail for a meaningful identification of delays to be made. These as-built start and finish dates can then be stored in the programme software which allows static bars to be created which reflect the as-built programme but without logic. The next task is to identify the actual logic relationships to create a logically linked network such that each activity has scheduled start and finish dates that match the as-built durations already identified.  Delays are then added to the programme as separate activities by identifying those parts of the as-built durations that are periods of delay. This can be seen in the first part of the programme above. It may be possible and appropriate to identify contractor caused delay as well as Employer’s delay (EOT events) in order to analyse potential concurrency as in the example above. The delays are then collapsed out of the as-built programme, and there are various approaches to determining the effect of each event. The delays can either be collapsed sequentially from the end of the project to the start, or all the delays can be removed with a single collapse and reintroduced sequentially from the start to see what effect each has on the completion date. In the example above it can be seen that there is potentially a concurrency situation. The as-built critical path indicates that the delay to activity 2 (for which the contractor is responsible) is driving the completion date, but say that this was the work to remedy a defect discovered upon completion of the work to activity 2 on 1 February leading to the subsequent completion of the activity on 7 February. Further, say the delay to activity 4 for which the employer was responsible was a variation to work that had been otherwise completed on 25 January leading to procurement of additional materials and completion of the work on 6 February. It could then be argued that the employer’s delay came first and at that time event 2 was on programme. The effect of collapsing the employer and contractor delays out in this situation would result in the conclusion that in fact at the time of the start of the employer delay to activity 4, this delay was critical thus causing a delay to completion of 3 days for which the Contractor should receive an extension of time. The subsequent contractor’s default caused a further delay to completion of 1 day. In order to show this, both delays have been collapsed out to determine the collapsed as-built completion date and the employer event has been added back to demonstrate the effect on the completion date. Selection criteria This method requires good as-built records and may be the appropriate approach where the planned programme either does not exist, or is a poor descriptor of the project. It may also be appropriate where regular progress has not been reported against the programme, or where progress data is neither reliable nor consistent. The method is often the most appropriate where the situation requires the retrospective analysis of delay (i.e. when a dispute arises after completion of the project). Issues One of the difficulties of the technique is the process of logically linking together each of the as-built activity bars in a way which is meaningful for the subsequent collapsing process. It is preferable for this to be informed by careful proper factual research including the advice of the factual witnesses who were involved at the time. A particular difficulty often arises when dealing with concurrent activities, namely finding that as the events are collapsed out of the as-built programme, other, perhaps insignificant, events are left that took longer than planned and that are preventing the programme analysis from collapsing. These may have to be more fully explained and then collapsed out as well. After all the events have been removed the resultant collapsed as-built programme should be checked carefully to ensure that it is in fact workable. A further issue is that the as-built programme is the result of all of the events that have occurred on site and it may be difficult to extract from that what were the true consequential effects on the programme of a single event. Advantages Its principal advantage is that it takes as its starting point the as-built programme, and it considers events in the context of the as-built sequence rather than the planned sequence of events. The method also has the appeal that the resultant collapsed as-built programme will retain any culpable delay, or at least events that took longer than planned which cannot otherwise be explained by identified delay events, as well as any differences in sequence and timing of activities from the planned programme. This removes the argument often made against the as-planned impacted method that delays measured against the planned programme ignore the fact that the contractor did not in any event comply with his own planned durations and was in culpable delay. Compared to time impact analysis, this technique is cheaper and relatively simple to undertake and its comparative simplicity is also an advantage in terms of presentation. It is particularly well suited to projects of a linear sequential nature. Disadvantages The method has a number of drawbacks, the greatest of which is the difficulty in establishing retrospectively the as-built logic. Others include the criticism that when identifying periods of delay other work to an activity might have been going on at the same time, and the subjective nature of arguments such as that by removing an event causing delay other options could have been available to the contractor. There is no question that in a complex situation where there are a lot of events, high degrees of concurrency, and where perhaps the as-built programme is not sufficiently detailed, then this method of analysis can be difficult to apply and it may not therefore be appropriate.
CJ-0620
|
|||
|
© Brewer Consulting |
|||
 |
|||