4 types of logical relationships or dependencies
i am reviewing a schedule that has a total of relationships and are . Also, from construction perspective, SS relationship increases the. In a project network, a dependency is a link amongst a project's terminal elements. The A Guide to the Project Management Body of Knowledge (PMBOK Guide) does not define the term dependency, but refers for this term to a logical relationship, (Project work started) SS (Project management activities started). Start to. PDM defines 4 Logical Relationships to represent Project Dependencies. This post to describes Start to Start (SS) Relationship. Start to Start is one of the 4.
Fortunately, Primavera P6 Professional can highlight activities that match the respective filter criteria.
File:Activity-on-node diagram showing SS relationship drag miyagi-marugoto2012.info - Wikimedia Commons
In this way the scheduler views the entire project and focuses in on highlighted activities that require review. We have in Figure 1 our demonstration project. We first want to display predecessor and successor details to support review of the FF relationships. In the columns feature dive into the lists category and select predecessor details and successor details, Figure 2. Figure 2 Move them over to the selected options, Figure 3.
Figure 3 The schedule with predecessor and successor details is displayed in Figure 4.
If we look closely we can spot each activity that has either a FF predecessor or successor. To highlight our FF associated activities select the filter feature and create the filter displayed in Figure 5.
Figure 5 The parameter in this filter is either predecessor details or successor details.
Start-to-Start - Project Management Knowledge
This filter captures all activities that have predecessor or successor details that contain the abbreviation FF. Figure 6 When we select OK all activities that have either a FF predecessor or successor are highlighted in blue, Figure 7. Now we can quickly see to inspect each instance of FF relationships in the schedule and consider possible replacement with a FS relationship. If other types of relationships are used, they shall be used sparingly and with full understanding of how the relationships have been implemented in the scheduling software being used.
Ideally, the sequence of all activities will be defined in such a way that the start of every activity has a logical relationship from a predecessor and the finish of every activity has a logical relationship to a successor".
Microsoft recommends to use SF dependency for just-in-time scheduling. There are three kinds of dependencies with respect to the reason for the existence of dependency: Causal logical It is impossible to edit a text before it is written It is illogical to pour concrete before you dig the foundations of a building Resource constraints It is logically possible to paint four walls in a room simultaneously but there is only one painter Discretionary preferential I want to paint the living room before painting the dining room, although I could do it the other way round, too Early critical path -derived schedules often reflected only on causal logical or discretionary preferential dependencies because the assumption was that resources would be available or could be made available.
over use of SS relationships?
Since at least the mids, competent project managers and schedulers have recognized that schedules must be based on resource availability. The critical chain method necessitates taking into account resource constraint-derived dependencies as well.
Leads and Lags[ edit ] Dependencies can be modified by leads, and lags. Both leads and lags can be applied to all 4 types of dependencies.
PMBOK defines lag as "the amount of time whereby a successor activity will be delayed with respect to a predecessor activity".
When building two walls from a novel design, one might start the second wall 2 days after the first so that the second team can learn from the first.