Before I get started, I want to let you know that the following is based on my experience with three software packages. While the basic concepts are the same for most software in this category, the specifics of how they work may be different.


Constraints


Last month, I told you that using floating tasks is the best way to build a schedule. However, some tasks may need restrictions. In a schedule, these restrictions are called constraints. While allowing a task to remain floating, constraints limit the start or end date. Each software package has its own particular set of constraints, but the two basic constraints are “no earlier than” and “no later than.” For example, your schedule shows that the utility conduit can be finished by Aug. 1 without affecting the completion date. However, the utility company requires the conduits be installed by July 1. This is where we would use a “finish no later than” constraint to force the task to end on July 1.


While it can be tempting to use many constraints, they can cause problems in your schedule. Constraints are somewhat invisible because they are a property of the task and are not shown on the Gantt chart. I prefer using milestones, which can be more self-explanatory. Properly labeled milestones tell you why they are present on the schedule. For instance, I always make “notice to proceed” my first milestone. The name makes it clear that it is a fixed date and records the fact that I was authorized to start the work on that date.


Resources


Let’s assume you have created all of your tasks, made all of the links and adjusted your durations to comply with the completion date. The question now is: do you have enough time to actually complete the work? This is when the software’s ability to assign resources to the tasks can be used. (Resources are workers, material, equipment, etc.)


The first requirement is to define your calendars, if you have not already done so. This is where you can set up workdays, work hours and holidays. Most programs come with predefined calendars, so all you have to do is fine-tune them. You can also set special schedules, such as working on a weekend. 


The next step is to create a resource for each type of worker you anticipate using for the project, such as foreman, journeyman and apprentice. You should also set the cost per hour for each worker and the maximum number of workers available for each type.


After defining the calendar and resources, it’s time to assign resources to each task. You need at least three pieces of information to add a resource to a task, and, depending on the software you’ve selected, several more options and parameters may be available. The three basic items are duration, number of workers and number of hours. Often, you only need to enter two, and the software will calculate the third. Optionally, you can also add costs for material, subcontractors, etc.


Managing the schedule


Now, let’s assume you have completed your schedule. All the kinks have been worked out, and it looks like you can finish the project on time and under budget. You can now use the software to track your project’s progress. Start by saving a “baseline” copy of the original schedule for use in comparisons when the schedule changes. Next, the software allows you to amend the number of hours used, the actual completion percentage and the amount of other resources used. As you update the progress, the software will calculate projections and show revised completion dates and resource requirements.


One of the greatest benefits of a fully loaded schedule (one with resources added) is the ability to predict the effect of changes, such as delays, change orders, weather and late material deliveries. When you add these events to your schedule, the impact on the completion date is immediately shown. This allows you to plan your reaction to the change, rather than react when it is too late to do anything. One of my favorite uses of scheduling software is charting the effect of unapproved change orders. I can easily see the repercussions ripple throughout the schedule, so I can prepare a detailed delay claim letter.


As these last two columns have shown, managing a detailed schedule can be time-­consuming. However, the rewards can be well worth it. I once had a boss who was always puzzled by my ability to know everything about my projects at the weekly meeting. I knew about my projects because I updated and studied all of my schedules regularly.