It has been a while since I last discussed Eli Goldratt’s Critical Chain and project management, but there is one more element to Critical Chain Project Management that I haven’t touched on.
Critical-path analysis assumes that a task is either dependent on another, or it’s not.
But what if two tasks require the same limited resource? What if they require the same expert’s time, or the same expensive piece of machinery? The two tasks aren’t dependent on one another, but they can’t be performed in parallel.
Suddenly our wonderful critical-path analysis goes out the window, and we have to tinker with the schedule until our resource isn’t in two places at once.
With a toy problem, this is easy enough to do by inspection. With a larger program, let a computer do the work.
Of course, if you don’t have this all plotted out ahead of time, you find out the hard way that Task B is wildly behind schedule, and that your critical path has shifted from Tasks C and F to Tasks B and E.
It’s no wonder why project leaders build a lot of safety into their schedules…