Hint of the Month - January 2025

How to decide on project activity sequencing relationships?

 

 

Most popular activity sequencing relationships in a project schedule are Start-to-Start (SS), Start-to-Finish (SF), Finish-to-Start (FS), and Finish-to-Finish (FF). Choosing the relationship between two activities in the schedule is not arbitrary. The type of relationships connecting activities, and any lag or lead durations between them, will directly impact the performance and overall duration of project completion, and could consequently impact on overall costs of the project. For example, an SS relationship with a lag time can be used when two activities can be executed in parallel, but the second one depends on partial delivery of the first at its beginning, so instead of waiting for the full activity duration of the first one to complete, the second activity can start after a certain lag time as soon as the first activity is started and began to deliver, which leads to much saving of time of the overall project schedule. Similar reasoning can be applied to deciding on when the other types of relationships can be used.