Slack

Slack is the number of days between the earliest and latest time that a Work Order can be started without delaying the Project. In the above example, the Foundation Work Order takes 20 days and the Sewer Work Order takes 25 days. The Foundation Work Order has 5 days Slack.

Critical Path

A Critical Path is any path between the Start and End points that has zero Slack. A delay on any Work Order on a Critical Path will cause the Project to complete later. In the above example, the top path is obviously the Critical Path. A Project can have multiple Critical paths of the same duration.

Duration

Duration can consist of either Working Time or Elapsed Time. Working Time is the actual time on the job while the Elapsed Time may include time waiting for other events to occur. In the above example, time should be allowed for the foundation to cure after the workers have left the job. Elapsed Time will always be greater than Working Time.

Working Time is calculated from the Work Order Planning. Planning provides for the entry of Crafts, the number of workers for each Craft and the estimated number of hours for each Craft. For example, 3 Mechanics for 15 hours. These estimates are used by the Scheduling System to ensure that the required Human Resources are available for the scheduled time period. Scheduling works in tenth of an hour increments. Project Management works in increments of 1 day. Time will be rounded up to the nearest eight hour day. For example, 3 Mechanics for 15 hours and 1 Carpenter for 20 hours would result in an estimated Work Order Duration of 3 days (20 hours rounded up to nearest eight hour day). All three Mechanics are assumed to be on the job for the same 15 hour period. The Duration field on the Work Order is automatically updated to reflect Working Time.

The Duration field can be manually increased to reflect Elapsed Time. It cannot be set to less than the calculated Working Time.

Work Orders with Duration, in the case where there is no planned labor, are used by the Project Management System to create Elapsed time activities in the Project matrix. Since there is no planned labor, these Work Orders cannot be scheduled.