Sometimes there are activities that should have a delay between them. For example, you prime the walls and then you need to wait 24 hours for the primer to cure before you can begin painting the walls. This “waiting time” is called lag time. Lag time is considered positive time, because you are moving the successor tasks farther away from the predecessor task in the project.
The inverse of lag time is called lead time. Lead time is when you allow two activities to move closer together and even overlap. For example, let’s say you were remodeling a huge hotel ballroom. You believe it’ll take five days to prime all of the walls in this ballroom. You wouldn’t necessarily need all of the walls primed before you could begin the activity of painting. We could sequence the activities as finish-to-start but add lead time to the painting activity to overlap the priming activity.
While lead time allows activities to overlap there’s another possibility for larger projects called “fast tracking.” Fast tracking allows entire phases of a project to overlap. You might see this in larger construction projects where the foundation of a building isn’t completed all the way around but the skeleton of the building is being constructed just steps behind the construction phase. The problem, and danger, with fast tracking is that it increases risk in the project. If there’s a problem with the first phase deliverable it’s likely to impact all of the phases that have overlapped it.
Finally, the most practical approach to speeding up a project’s completion it to “crash” the project. Crashing means that the project manager will add labor to the project work in order to complete it first. This is fine as several assumptions are true:
- The work is effort-driven. Effort-driven work means that the completion of the work can be reduced by adding additional effort to the activities. A task to pull network cable through a building can be completed faster with eight electricians than with four. Activities such as testing, some construction, and manufacturing are of fixed duration – which means no matter how much effort you apply it’ll still take the same amount of time to complete the task.
- The skill set is capable of doing the work. A project manager can throw more labor to effort-driven work, but if that labor doesn’t know how to complete the work it won’t be completed any sooner if at all. Competency is an input to crashing the project.
- The law of diminishing returns is acknowledged. Just because you can add labor to the activities to complete them faster doesn’t mean it’s good business to do so. At some point it’s not going to be cost effective to add eight network engineers to pull network cable, because of the cost of the labor in ratio to the profit the network job offers. The law of diminishing returns also governs that work will take some amount of time, regardless of the effort, to complete. You can’t add labor exponentially and finish the work in seconds.
- You have the money. Crashing increases the costs of the project, because of the added labor. Many project managers don’t have to worry about paying for the labor of the project team, because the parent organization pays for the labor. Project managers that do have to consider the labor costs or project managers that work with contractors know that the more effort a project team adds to the project the more the effort is going to cost. Time is, as they say, money.
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