Advanced Knowledge

When speaking colloquially in project management about a project network diagram, we are actually referring to the so-called Activity-on-Node (AON) Network. Every activity is visualized using a node – and therefore the name. The arrows, however, symbolize the logical relationship. Network diagrams contain predecessors and successors. However, this does not mean temporal dependencies, but logical ones. In the standard visualization of the arrows the tails leave the predecessor on the right-hand side whereas the arrowheads enter the successor on the left-hand side. When we want to calculate a network diagram there are calculation operations that take place only within one single activity node. The logical relationship between this activity node and other activities does not matter. So, the start time plus the duration always equals the finish time, and vice versa the finish time minus the duration always equals the start time.