GANTT - Set Manual Start Date + Define Predecessors (for the same task)

DamianK

// Current situation

Currently, adding (1) manually a start date for a specific task AND (2) defining certain predecessors for the same task is not possible

// Problem Description

Let's imagine, we have the following two tasks to plan:

• Task 1: Starting at day 1 and a duration of 10 day
• Task 2: Starting at day 15 and a duration of 10 day, predecessor is task 1

--> Currently I have three options to implement this

• Option 1 (Don't use the predecessor function): Task 1, manually set start date to day 1 & Task 2 set manually start date to day 15. ---> Problem: When I have to extend Task 1 to a duration of 20 days, Task 2 remains as it is.
• Option 2 (Use the predecessor function): Task 1, manually set start date to day 1 & Task 2 set predecessor as task 1. ---> Problem: Task 2 starts directly after Task 1, i.e. at day 10 and not day 15 as it should be.
• Option 3 (Use the predecessor with lag function): Task 1, manually set start date to day 1 & Task 2 set predecessor as task 1 with lag 5 days. At the beginning this looks good. However, when I have to extend the duration of Task 1 to 15 days, Task 2 starts only at day 20, because the "lag" is still added, despite it is no longer relevant.

// Requirement Description (Solution):

It shall be possible to manually define a start date of a specific task but still allow the definition of predecessors. Therefore, in the background, such a task should always have (1) the manually defined start date and (2) a automatically calculated start date (based on the predecessor). Now, the system should always check which of these two dates is "more in the future" and only display this one as actual start date of the specific task in the Gantt.