Delay Analysis Techniques
The goal of delay analysis is to calculate the construction project delay and work backward to try to identify how much of it is attributable to each party (contractor, owner, or neither) so that time or/and cost compensation can be decided.
Excusable versus Non-excusable Delays
Construction delays are basically either excusable or non-excusable. Claim that whether a delay is non-excusable or excusable depends on the clauses in the contract. It’s noted that standard construction contracts specify types of delay that will allow the contractor to an extension of time. For instance, in some construction contracts, unusual or unexpected weather conditions are not considered as excusable and so these contracts don’t allow for any time extensions.
An excusable delay, in general, is owing to an unforeseeable event beyond the contractor’s or the subcontractor’s control. Here below some delays resulting from the following issues are known as excusable:
1-General labor strikes,
4-Differing site conditions or concealed conditions,
5-Unusually severe weather,
6-Lack of action by government bodies, such as building inspection.
Compensable versus Non-compensable Delays
In some studies, claim that an excusable delay can be classified as “excusable compensable” and “excusable non-compensable”. It’s stated that compensable delays are caused by the client or the engineer. The contractor is typically entitled to an extension of time or recovery of the costs related to the delay, or both. Factors that are specified in the construction contract resulting in delays such as differing site conditions, changes in the work, access to the site are some examples of compensable delays. According to excusable delays may be compensable.
Excusable non-compensable delays are normally beyond the control of either client or contractors such as unusual weather conditions, natural disasters, wars, national crises, floods, fires, or labor strikes. They add that usually the main contractor or subcontractor is entitled to a time extension, but no additional compensation.
If a delay is compensable or non-compensable basically depends on the issues of the contract. The contract determines the types of delays in detail and for which delay the contractor is entitled to an extension of time or monetary compensation.
Types of Delay Analysis Techniques
Delay analysis is an analytical process that should be employed with construction project documentation along with collected data from the project site. Delay analysis method selection depends on the variety of factors and the available records.
There are five commonly used delay techniques:
– Impacted as-planned method
– Time impact analysis method
– Collapsed as-built or but-for analysis method
– Windows analysis method
– As-planned versus as-built (Total time) method
1-Time Impact analysis method
The analyst determines the amount of construction project delay resulted from each of the delaying activities successively by calculating the difference between the project finish date of the schedule after adding each delay and that prior to the addition.
2-As-Planned vs. As-Built
Under this method, all delaying events (EC, EN, and NN delays) encountered on the construction project are depicted on the as-built time schedule. The difference between the as-planned and as-built finish dates is the amount of time for which the claimant will request for compensation. The critical path is determined once in the as-planned and again in the as-built time schedule. This technique and the net impact technique utilizing the bar chart are similar in that they all show the net effect of all claimed delays.
This method measures the impact of the delays on the contractor’s as-planned CPM time schedule. The different delays are formulated as activities and added to the as-planned network in a chronological order showing the effect of each delay at a time and demonstrating how the construction project is being delayed. The amount of delay equals the difference in end dates between the time schedules before and after the impacts. The technique can be used for the analysis of delay during and after the project finished. Delay analysis of the sample project using this technique was carried out by sequential addition of the delays to the as-planned time schedule.
This delay analysis technique involves interim assessment of delay on updated schedules at specific periods of the construction project. This window analysis is similar to the “snapshot technique”, “contemporaneous period analysis”. First, the total project duration is divided into a number of time periods (snapshots or windows) usually based on major changes in planning or major construction project milestones. The time programme within each window is updated to reflect the actual duration and sequence at the time of the delay while the remaining as-planned time schedule beyond the window period is maintained. Analyses are performed to determine the critical path and the new end date. This new end date is compared with the as-planned finish date prior to this analysis to give the amount of delay during that window period.