Highlights. What one procedure affects every construction project, no matter where it is or what size it is? The answer is scheduling, and to help you get a good handle on the complex subject, Jennifer J. Chapman shares the scheduling expertise she gained in nine years as a civil engineer. This article discusses in general terms how a schedule comes to be and how—and why—it is updated. Always wondered about some of those mysterious terms like “float” and “late start date”? Wonder no more; this article tells you what they mean. Finally, the article also illustrates the many ways in which an accurate, updated schedule proves invaluable on any construction project.

What Is the Construction Schedule?

Public owners starting a construction project have a powerful tool available to use in managing their construction projects: the construction schedule. A properly created and updated schedule gives the owner specific information on the status of the project.

Depending on how the contracts are set up, the construction manager or general trades contractor creates and updates the construction schedule. Computer software for this task may be Primavera, Microsoft Project, or something similar.

Most public construction projects use the critical path method (known as “CPM”) to create and update the schedule. The CPM is defined as a mathematically based algorithm that uses at a minimum the individual activities, the durations for the activities, and the dependency among the activities to create the schedule.

As construction progresses, updating the schedule shows the progress on each activity. Updating the schedule creates a tool of great importance to the owner. Why? Because it lets the owner know any changes to a red-letter date, the project completion date.

What Are the Steps for Creating a Schedule?

Milestones. The Front End Documents set forth the specific scheduling requirements and who is responsible for managing the schedule. During development of these documents, the owner needs to work with the architect and construction manager to develop the milestones for the project. Milestones are activities that are significant events for the project. They are project specific. Some examples are “contractor to submit shop drawings for long-lead-time equipment,” “dried-in” (the weather-tight date for the building), and “project completion.” Also, if the project is to be turned over to the owner in phases, a milestone for the completion of each phase should be used.

For renovation construction projects of an occupied facility, the owner, architect, and construction manager should develop milestones related to the dates and number of days the different areas of the facility will be available for construction. The expertise of the architect and construction manager helps the owner to develop milestones specific to the project.

The Baseline Schedule. Once contracts have been awarded to the prime contractors, the next concept a public owner needs to understand is the development of the baseline schedule. The baseline schedule is the original schedule produced after contracts have been awarded to the prime contractors. The Front End Documents set forth how long the prime contractors have to submit their information for the development of the baseline schedule, and also the length of time they will have to review, comment on, and accept the baseline schedule.

The owner, architect, engineer, construction manager, and prime contractors all play a role in the development of the baseline schedule. The owner’s role is to give input regarding owner- furnished equipment and furnishings, durations for move-in, and any other impact the owner will have during the construction of the project.

For a renovation construction project, the owner should also be sure the baseline schedule incorporates any time necessary to move furnishings out or protect equipment before the contractors start their work.

The prime contractors and construction manager have the primary role in the development of the baseline schedule. The prime contractors supply the construction manager (or the general trades contractor) with a list of all the activities necessary for the completion of their scope of work, the durations for each activity, and the predecessor and successor activities for each activity. The predecessor activities are the activities the contractor needs completed before its own activity can start. The successor activities are the activities that can be completed after the contractor’s activity.

It is also becoming more common for the prime contractors to be required to provide information on their resources for each activity. The resources for the activity are the manpower and equipment necessary to complete it. A schedule that incorporates these is known as a “resource-loaded schedule.”

The construction manager (or general trades contractor) takes all of the information from the prime contractors and owner to develop the baseline schedule. A draft baseline schedule is given to the architect, engineer, owner, and prime contractors for review, comment, and acceptance.

Some Important Terms

When the owner receives the baseline schedule, understanding a number of scheduling terms will help to make the schedule make sense. Duration, critical path, float, early start, late start, early finish, and late finish are the next new terms for an owner to understand.

• The duration of an activity is the number of work days it should take the contractor to complete it.

• The critical path is the sequence of activities with the longest overall duration. Activities on the critical path cannot be delayed without delaying the project completion date. There are zero days of float for activities on the critical path. By definition, an activity with float is not on the critical path.

• Activities not on the critical path have float, defined as the number of days an activity can be delayed without affecting the project completion date.

• The early start date is the first available date an activity can start.

• The late start date is the latest date an activity can start without impacting the critical path. Note: For activities on the critical path, the early start date and late start date are the same.

• The early finish date is the date an activity should finish if it is started on the early start date and completed within the permitted duration.

• The late finish date is the latest date an activity can finish without impacting the succeeding activities. Note: For activities on the critical path, the early finish date and late finish date are the same.

Once the owner understands these key terms, its personnel can properly communicate with the architect, construction manager, and prime contractors about the schedule.

How Is the Schedule Used?

Most construction documents require the schedule to be updated at least monthly. This means the prime contractors give the person updating the schedule the dates they started an activity and the percentage of completion for each incomplete activity. For completed activities, they give the completion date.

This information is put into the computer software, and an updated schedule emerges. This will allow the owner to know if the project is on time. The updated schedule allows the construction manager or general trades contractor to know if a prime contractor is falling behind schedule, if any of the prime contractors are using the float, and how the activities on the critical path are progressing.

As the schedule is updated, the activities on the critical path often change. For example, if a non-critical activity takes longer than its duration and uses up its float, it will be pushed onto the critical path. During construction, this can happen for many reasons, like weather delays, a delay in the fabrication and delivery of steel, or a prime contractor’s not having the necessary manpower on site to complete its work in the allotted time, causing another prime contractor to be delayed. This explains why it is critical to keep the schedule updated. Frequent updating allows for the close monitoring of the activities that are on the critical path or within a few days of being on the critical path.

The schedule should also be used during the weekly coordination meetings. The person managing the schedule can print a one- or two-week “look ahead” schedule. A “look ahead” schedule shows the activities scheduled to start or finish in the next one or two weeks. The “look ahead” schedule should be discussed at the coordination meetings so all of the prime contractors know the work that is upcoming and can coordinate with each other.

The person managing the schedule should also incorporate all change order work. If the change order adds or subtracts days to the contract and changes the completion date, this information must be updated on the schedule. Of course, such a change requires signed change orders; it cannot be accomplished merely by slipping the new date into the schedule.

By incorporating the activities, durations, early start date, and resources for change order work, the person managing the schedule will know how to plan so that the change order work will have a minimum impact on the critical path. Having a resource-loaded schedule is also key to effective management of the prime contractors because the owner and construction manager (or general trades contractor) should know if the contractor has the necessary manpower and equipment at the job site to complete the activities within the required duration.

If the architect, owner or construction manager sees that a prime contractor does not have the resources available on site to complete the activity, they can give notice to the prime contractor. The key information in this situation is to have the prime contractor’s resources incorporated into the schedule, allowing for proper management of the prime contractors.

A properly updated schedule can also be used effectively to defend the owner against delay claims by prime contractors. For example, if prime contractor A informs the architect or construction manager that it is being delayed in performing its scope of work by prime contractor B, the architect or construction manager can examine the schedule to see if the activities are on the critical path or close to falling on the critical path. If the delayed activities are on the critical path, the architect or construction manager should take steps to have prime contractor B finish its work so as not to impact prime contractor A. The architect or construction manager will need to work within the guidelines of the Front End Documents regarding supplementation of a prime contractor’s work. By taking steps to work with prime contractor B, the owner can reduce its exposure for a claim by prime contractor A.

In this example, if the activities are not on the critical path and are not close to falling on the critical path, the owner should have a very good defense against prime contractor A because there is no impact on the completion date.

A resource-loaded schedule can also assist the owner to defend against acceleration claims by a prime contractor. For example, if prime contractor A has a claim for additional cost to accelerate its work, the schedule should show if the work accelerated is on the critical path. Using the resources associated with each activity, the architect can make a comparison between the planned resources from the baseline schedule and the actual resources used to complete the activity. This information is critical to defending the owner against claims.

Summing It Up

The construction schedule is a valuable tool to inform the owner on the status of the project. It can help the owner with planning: when to order owner-furnished equipment and furnishings and have them delivered, when to schedule move-in, and when to train its personnel on operating the equipment. The schedule also plays a key role in managing the prime contractors and defending against claims. Best of all, with a properly updated schedule, there should be no surprises about the project completion date.

Next month, as a follow-up to this article, we will shine a spotlight on a particular procedure for scheduling that is growing in popularity: Lean Scheduling.