Construction Delays and Other Claims - Construction Project Scheduling and Control - page 351

which the contractor plans to perform the work and the owner's acceptance of that
plan. The 2007 version of the AIA A201 General Conditions document requires the
contractor to submit a schedule that complies with the contract completion date. Most
contract forms used by public and private owners today also require a schedule pre-
pared by the contractor and accepted or approved by the owner. Such schedule, once
adopted as the baseline schedule in the contract, becomes a very important document
because it constitutes the yardstick for measuring any variation if it is properly updated
and maintained. Because of a lack of knowledge or experience, negligence, or other
reasons, many contractors commit errors or submit faulty schedules. Following is a
list of some of the frequent scheduling mistakes that some contractors commit.
1. Baseline schedules that don't show logic : Some contractors use spreadsheets or
simple bar charts as schedules. Spreadsheets are not scheduling programs,
and they are used merely like color ribbons to indicate when the contractor
intends to start and finish each activity without showing interdependencies.
When an activity is delayed or shifted, there is no mechanism to reflect the
impact of this delay or shifting on other activities.
2. Baseline schedule with dates rather than logic : Some schedules, even if they are
built using scheduling programs, use “events” rather than “activities.” For
example, instead of showing “Excavation” as a 20-day activity, the schedule
shows two milestones (events): “Start Excavation” and “Finish Excavation.”
There are several problems with this approach. Some contractors use con-
straints to “fix” the date of an event. This negates the introduction of logic
in the schedule. This approach also deprives the control manager (on both
the contractor's and the owner's side) from evaluating the percent complete
of that activity.
3. Overuse of constraints : Instead of logic ties, the contractor “schedules” activ-
ities by assigning start and finish dates to them, usually by the use of “Con-
straints.” Similar to the previous example, activities “get nailed” with such
constraints and cannot react to logic and other changes. Often in construc-
tion, activities get delayed, omitted, or adjusted, or they finish early. Such
changes can have an impact on succeeding activities but won't show if activ-
ities are constrained. 14
4. “ Erasing footprints ”: A contractor may build or update the schedule as the
project progresses without keeping a copy of the original or previous updates.
This schedule will be an “as-built” schedule. It shows how the project was
actually built, not how the contractor intended to build it. This conduct leaves
no footprints to track and no baseline to compare the progress to.
5. Unrealistic baseline schedules : Some contractors don't realize that a baseline
schedule that is approved by the owner may be a legal and binding document.
14 Some computer programs introduce different types of constraints: some are subject to logic, and some
override logic.