Diverse studies have tried to identify the variety of reasons for delays in projects to propose methods to mitigate them via a delays analysis. Construction projects often suffer from delays due to various reasons, which can have a severe financial impact on the project. The analysis of the delay impact, the causes, and the effects of the delaying activities is complicated. A delays analysis requires an expert with extensive knowledge of construction projects, means, methods, scheduling, and developing a sound methodology to conduct the analysis.
Most of these delayed claims reach the expert after completing the project, and hence it becomes difficult to analyze efficiently. Experts have to verify schedules, events, sequence of work, changes during construction, and its delay impact.
This paper will address these challenges and the various delay analysis methods. One of the complications of delay analysis is that the delays can be caused by a few of these listed causes or a complex mix of these causes. Further time of delay occurrence and who caused what delay adds to the difficulty of the analysis. The impact of delays in the Construction Industry and methods to reduce consequences on business operations, stakeholders, and customers.
Below is a list of common delay causes encountered on construction projects:
- Errors and omissions in the contract documents
- Missing information
- Not having a phasing plan in the bid documents when the site work has to be done in phases
- Conflicting information that needs design revisions
- Owner-caused delays for reasons under their control
- Scope changes
- Limiting contractor’s access to parts of the site
- Unsolicited information’s in the contract
- The fear attitude of the owner-employee
- Cash flow
- A higher-level political factor that impacted the project’s progress
- Contractor-caused delays for reasons under their control
- Not having enough labor force on site
- Contractual problems between the prime contractor and subcontractors
- Cash flow issues
- Lack of proper planning and management of the project
- Poor bidding
- Delays for reasons beyond the contractor or owner’s control
- Out-of-state manufacturer’s shutdown
- A subcontractor going out of business in the middle of the project
- Unusual weather conditions
- Personality conflicts between the project’s team
- Unfortunately, sometimes the team makes the work atmosphere difficult, resulting in delays. In this case, each party blames the other for the delay.
Materials and Methods
One of the main steps in the delay analysis is to research the project’s documents to identify causes like those above that delayed the project. The methodology used in determining the impact of these factors is the heart of the difficulty of this type of analysis. Using the critical path method (CPM) scheduling provides analysts with the needed tools to conduct a proper analysis. The CPM method and the relevant software give the user the ability to tie the schedule’s activities by logical relationships by performing the following basic steps:
- Define the activities
- Assign duration for each of the activities
- Identify the predecessor and successor activities
- Allocate the proper relationships similar to those described above
- The software automatically performs the CPM calculations, displays the schedule, gives you the completion date, and identifies the critical and non-critical activities
- Update the schedule and clearly note the change in the completion date
- Manipulate the relationships and duration of activities to change the logic of the schedule to recover a delay and bring back the completion date to the desired date
- Insert a delay factor to the activity and immediately read the new completion date
- Identify the critical activities. These are the activities that do not have any room (float) for any delays. A 3-day delay on a critical activity delays the whole project by 3 days unless the revised logic of the schedule dictates otherwise
- Identify non-critical activities. These activities have different amounts of float
- A float of 20 days can delay this activity up to 20 days without impacting the whole schedule.
When the first submitted schedule is approved, it is considered a base schedule for future updates and delay analysis. That means the owner needs to carefully review the schedule and the critical path before approving the schedule.
Some of the elements that need careful review to follow:
- Verify that the start and completion dates of the whole project match the contract dates
- Check that the assigned durations are realistic
- Review the logical ties between the activities
- Look through the critical path and check what activities are critical
- Check to see if the schedule shows the phasing required
Other different methods that are commonly used to analyze delays are as follows:
- As-Planned vs. As-Built Method
- Impacted As-Planned Method
- Collapsed As-Built or “But For” Method
- Window Analysis Method
- As-Built Method
- Contemporaneous Method
As-Planned vs. As-Built method:
The expert analyst compares the dates and durations of selected activities shown on the as-planned schedule with the actual dates and durations on an as-built schedule and considers the difference to be the delay on the job. Thus, all delays are incorporated based on actual as happened, in the planned schedule to get the built-up schedule.
This is a very simplistic view of the delay claim because it ignores the following vital factors:
- The cause of the delays
- The timing of the individual delays, their impact on the schedule, and the ability to attribute the correct number of delay days to the correct, responsible party
- The impact of concurrent delays
- The fact that the logic and sequence of the as-planned schedule may have changed through the project due to numerous delaying factors
Impacted As-Planned Method:
In this method, the expert analyst lists the excusable delays (or delays where a time extension is owed to the contractor) and inserts the extended duration to the relevant activities. The analyst reads the revised completion date, calculates the days between this date and the as-planned completion date, and determines the number of days owed to the contractor. Thus, selected excusable delays are incorporated based on a number of days concept in the planned schedule to get the impacted schedule.
The sources of error in this method follow:
- It ignores the actual as-built schedule and events on-site.
- It assumes that the logic of the as-planned schedule reflects the reality on site.
- It ignores the inexcusable delays that may have been concurrent to some of these inserted delays, impacting the number of days owed to the contractor.
- Since the analyst is only using the as-planned schedule, this method doesn’t incorporate changes in logic and out-of-sequence work.
Collapsed As-Built or “But For” Method:
In this method, the expert analyst takes the actual as-built schedule and takes out the duration of all the excusable delays (delays rightfully owed to the contractor). This revision forms the collapsed as-built schedule. The analyst reads the completion date on the collapsed as-built schedule and considers this date to be the project’s completion date had the contractor not been delayed. The expert analyst calculates the days between the collapsed as-built and the completion date from the as-built schedule and considers these days to be the days owed to the contractor. Thus, selected excusable delays are incorporated based on a number of days concept the activity-wise in the planned schedule to get the impacted schedule.
The sources of error in this method follow:
- It depends on the as-built schedule to be accurate.
- The excusable delays removed from the as-built schedule are assumed to be excusable without a complete analysis of these delays, their causes, and concurrencies. That means subjective assumptions and judgments have been taken and need to be examined.
- It does not factor in how the sequence of operation changed, any acceleration that took place, and any recovery because the as-built schedule represents what happened on-site without addressing the causes and effects of delays along the way.
- In some cases, where an as-built schedule does not exist, the analyst recreates it based on their research. This product does not reflect the planned logic of activities or the planned critical path.
Window Analysis Method:
This method is based on analyzing the delay over the entire schedule, dividing it into windows with a selected duration, most commonly monthly. The analyst looks at the activities within the selected window and updates the activities, incorporating the delays within the selected window. Updating the selected window changes the as-planned schedule to an as-built schedule up to the end date of the selected window and becomes the basis for projecting the remaining activities from the end of the window to the completion of the project. Thus, selected excusable delays are incorporated based on a number of days concept the activity-wise in the monthly part of the original planned monthly schedule to get the impacted schedule.
The sources of error in this method follow:
- Need to have accurate as-built information on the start and finish dates of the windows
- Need for the original base schedule to be accurate
- Delaying activities outside the selected window that have an impact
This method is used in the absence of reliable schedules on the job. In this case, the analyst recreates a schedule based on actual information. The analyst determines the logical ties between the activities to form a retrospective schedule, which becomes the basis for analyzing the effect of the delays. Durations are given to the activities based on a reasonable time to finish the various activities. The delays are then inserted in the newly created schedule and then compared with the actual as-built durations to calculate the number of delay days. Thus, selected excusable delays are incorporated based on a number of day’s concepts in the activity-wise on the just prepared “post-completion envisaged schedule”.
The sources of error in the method are these:
- The analyst has to be very experienced in construction means and methods
- There are a lot of judgment calls by the analyst that needs to be examined
This is usually the preferred method of analyzing delays. In this method, the analyst looks at the schedule and actual site progress on the starting date of each delay and then inserts the delays in the schedule. The new completion date is compared to the original completion date to determine the delay days. This way, the impact of concurrent delays is incorporated, and the new critical path reflects the reality on-site and effects of the delaying causes.
The sources of error in this method occur when the analyst does not have the following:
- Good documentation to reflect the actual site progress
- Accurate schedule updates
In conclusion, the analyst has to select the best method to use for analyzing delay claims. Each approach has its advantages and drawbacks. Sometimes the nature of the case, available time, document availability, or budget consideration influences the method selection.
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