What is sequencing activities

SS — Start to Start — an activity must start before next can start. For example, laying of foundation pillars can start only after digging of the foundation has started. SF —Start to Finish - an activity must start before next can finish, this is the rarest and should be avoided. An example is: install of new oil pipeline must start before shutting off the old pipeline can finish.

The most popular method used for sequencing is the Precedence Network Diagramming method. Activities are connected in such a diagram, thus showing their sequence from the start to finish of the project. Some of them may be sequenced even in parallel or with overlap. Optional or discretionary preferred or soft logic — this is due to best practice or desire. The project schedule development uses the outputs from the processes to define activities, sequence activities, estimate activity resources, and estimate activity durations in combination with the scheduling tool to produce the schedule model.

In the sequence activities data flow diagram, every activity and milestone except the first and last should be connected to at least one predecessor with a finish-to-start logical relationship and at least one successor with the finish-to-start or finish-to-finish logical relationship.

Sequencing can be performed by using project management software or by using manual or automated techniques. Moreover, the schedule management plan identifies the scheduling method and tool to be used for the project, which will guide how the activities may be sequenced. Drywalling, 4. The last three tasks, windows, roofing, and landscaping, might be at the bottom of the list, but they are dependent only on the framing 2. Mandatory vs. Discretionary Dependencies Until now we have dealt only with mandatory dependencies , which is when the task relationships are physically absolute, or mandated by contractual or legal requirements.

There is a bonus for early completion. External vs. Internal Dependencies Dependencies also fall under the categories of Internal vs. Internal Dependency: A task relationship between two tasks within the same project. External Dependency: A task relationship between two tasks within different projects.

Leads and Lags Sometimes there need to be gaps between tasks. A lead time is the amount of time that a task can be advanced relative to its relationship with a predecessory activity.

For example, landscaping can begin 5 days before the framing is complete. This would be an FS relationship with a lead time of 5 days. A lag time is the amount of time between tasks before a task can begin. For example, framing cannot begin until the concrete foundation has cured for 10 days.

This would be represented with an FS relationships between Pour Foundation and Framing, with a lag time of 10 days.