Start to Finish Relationships - to use them, or not?
In Primavera P6, driving relationships appear on the Gantt Chart as solid Finish -to-Start relationships make it easy to separate driving from. this is not true there is no advisable reltionships in p6 the reltionship between activities put as per the logic sequences of work and the finish to start relationship . As Primavera P6 used PDM method for scheduling so these relationship types In finish to start relationship, start of successor activity is controlled by finish of.
In this relationship one activity cannot finish until another related activity has finished. A possible example from the research industry is that documentation cannot complete until experimental testing described by that documentation has finished. In this not so common relationship one activity cannot finish until another activity has begun.
An example is the use of a generator that cannot cease until the power is activated.
Primavera P6 Relationships Explained - projectcubicle
Lag and Leads Lags and leads have a significant impact on the length of the schedule. A lag describes a required time between activities. In the FS relationship this means that the second activity cannot commence until a scheduled period of time has elapsed after the completion of the first activity.
The most common example is concrete, in which a lag is inserted between activities to allow the concrete time to cure before the successor activity can proceed. After the lag time period has expired then the second activity of installing framing on the concrete flooring can commence.
P6 Milestone Activities With Invalid Relationships | Plan Academy
A lead has the opposite effect on the schedule. A lead is the amount of time that an activity can start before the completion of the first activity. Many schedulers refer to lead as a negative lag.
- P6 Milestone Activities With Invalid Relationships
- Understanding Driving Relationships
- Start to Finish Relationships – to use them, or not?
It is worth noting that leads are not typically recommended and are often avoided by experienced schedulers. Fast Tracking Many times a scheduler will organize activities in a series format where activities are performed one after the other with pure FS relationships. However, the scheduler should consider whether these activities could be performed in parallel.
Fast Tracking is used when the scheduler decides to take risks and schedule activities in parallel, even though it is better to do them sequentially.
A simple example would be to start construction before design is finished. These risks are taken to keep the project on track or to have a chance to finish earlier. Crashing What do you do when fast tracking is not an option?
How do you compress the schedule in these situations? Well, if the project does not have strict cost constraints the scheduler could add additional resources to certain activities to complete them faster. Extra crews are added to a task to increase daily output and, therefore, complete the task faster without changing the required serial relationship between project tasks. This invariably results in increased costs.
Why Finish to Start is the most advisable relationship to be used in Primavera P6 ?
Other examples include applying different technologies to accelerate critical tasks, or changing work calendars to make Sunday a working day or have teams work additional hours. Crashing is often applied to critical activities and it also makes sense to look at activity drags. Crashing almost always increases cost.
In finish to start relationship, start of successor activity is controlled by finish of predecessor activity.
Types of Relationships in Primavera P6
For example you can build foundations of a building after you have done excavations. Or you can test a software after you have developed it.
In Finish to Start, relationship arrow originates from finish of the predecessor and finishes at start of the successor. It only means that start of successor activity is controlled by finish of predecessor activity. In FS relationship, successor activity can start before the finish of predecessor activity if lead is applied to successor. This type of relationship is mostly used in the schedule.
If you are confused about exact relationship between activities then go for FS relationship. Start to Start or SS: In start to start, start of successor activity is controlled by start of predecessor activity. For example when a project starts then project management activities are also started with it. Or you can start leveling of concrete when pouring of concrete is started.
It only means that start of successor activity is controlled by start of predecessor activity. In SS relationship, successor activity can start after the start of predecessor activity if lead is applied to successor.
For example, if construction of walls and plaster on these walls are connected with SS relationship, then to start plaster, some portion of the walls must have to be completed. Finish to Finish or FF: