Calculate Critical Path in Open Workbench

You can calculate critical path in Open Workbench (OWB). Critical path is a set of tasks in a project for which any delay or expansion lengthens the project or causes project deadlines to slip. The critical path determines the project's earliest finish date. Autoschedule uses the critical path value to determine the tasks that drive the project deadlines and constraints. The critical path is calculated using the dependency sequence and task duration. If you decide to schedule subnets, a separate critical path is calculated and displayed for each subnet and for each task that does not have dependencies.
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You can calculate critical path in Open Workbench (OWB).
Critical path
is a set of tasks in a project for which any delay or expansion lengthens the project or causes project deadlines to slip. The critical path determines the project's earliest finish date. Autoschedule uses the critical path value to determine the tasks that drive the project deadlines and constraints. The critical path is calculated using the dependency sequence and task duration. If you decide to schedule subnets, a separate critical path is calculated and displayed for each subnet and for each task that does not have dependencies.
To calculate the critical path, autoschedule your project or select
Tools
,
Critical Path
. You can view the project's critical path in a CPM Network view.
How Open Workbench Calculates Critical Path
Open Workbench calculates a project's critical path using a two-step process. The following rules govern how this two-step process is conducted:
  • Tasks that are part of the longest duration chain are on the critical path.
  • Project finish date is the sole reference date used to calculate both the early and late schedules.
  • Float can be zero, lesser or greater than zero.
  • Task status has no bearing on dependency violations or the critical path calculation.
  • A task that is not on the dependency network cannot have an early schedule or late schedule; hence, it cannot be on the critical path.
  • Resource constraints do not affect the critical path calculation.
To arrive at the critical path, the application performs two passes through the dependency network.
The First Pass
The first pass works forward through the network to determine the early start and early end dates for each task in the network, and calculates the longest duration path through the network. The project's reference end date is the project's defined finish date. If you did not define this date, the end date is the early end date of the last task in the network or, if there is more than one branch, the latest of the early end dates of the last task in each branch.
To calculate the early start date for the task's successor(s), the application starts with the first task in the network and adds the task's duration to the start date. Adjustments are made for gaps or overlaps by adding or subtracting from the duration. The early end date is calculated by adding the task's duration to the early start date. The application repeats this process for each task in the network.
The successor of a
Start-Start
dependency has the same early start date as the predecessor. The successor of a
Finish-Finish
dependency has the same early end date as the predecessor.
The Second Pass
The second pass works backward through the network starting from the project finish date to determine each task's late start and late end date. The last task of each branch of the network has a late end date equal to the project finish date. To calculate the late end date for a task's predecessor(s), the application subtracts the task's duration from the project finish date. Adjustments are made for gaps or overlaps by adding or subtracting from the duration. The late start date is calculated by subtracting the task's duration from the late end date. The application repeats this process for each task in the network.
The predecessor of a
Start-Start
dependency has the same late start date as the successor. The predecessor of a
Finish-Finish
dependency has the same late end date as the successor.
Calculate Float
Open Workbench calculates the float for each task by subtracting the early start date from the late start date.
Float
is the number of days that a task's initiation or completion can be delayed without adversely affecting the project finish date. Float is calculated using the following formula: Late Start - Early Start. Tasks with a float of zero (0) appear on the critical path.