Join Bonnie Biafore for an in-depth discussion in this video Paying more to shorten a schedule, part of Project Management Foundations: Schedules.
If the project finish date is more important than the budget, spending money to shorten the schedule is an option. This is known as crashing. Most common crashing technique is adding more resources to a task. This approach is effective, up to a point. If you add too many resources, work starts to slow down as people get in each other's way. Other options for spending more money include paying for overtime, paying fees for faster delivery of materials. Or paying for more expensive people, who can complete work quicker.
Like any technique for shortening the schedule, the tasks you want to crash are on the critical path, because they're the ones that directly determine the duration of the project. First look for the longest tasks on the critical path. Crashing can increase the risk for those tasks. For instance, when you hire unfamiliar workers. That's why it's good to keep the number of crash tasks to a minimum. Crashing part of one long task duration might cut all the time you need out of the schedule. By crashing longer tasks, you don't have to crash as many of them. After you have crashing candidates, evaluate those tasks to find the ones that are most cost-effective.
The trick is to find the tasks that offer the lowest cost for each week they shorten the project's schedule. Let's look at how this works using the sample project. Suppose the stakeholders say the project needs to finish a week earlier. The first step is to find the longest tasks on the critical path. In this view, the task list is filtered to show only the critical tasks, and they're sorted from longest duration to shortest. It turns out that write content and edit content are linked start to start, so shorting write content doesn't shorten the schedule.
So the tasks from edit content to layout employee handbook are the best candidates. They have durations from ten days down to four days. Crashing the schedule with shorter tasks might mean crashing more tasks. For example, if tasks are one day in duration and you crash them to half a day, you'd need to crash ten tasks. The next step is figuring out the most cost-effective tasks to crash. That means estimating how much each candidate can be shortened and how much it will cost.
From that, you can calculate how much it costs to crash per day. The crash table here shows crash info for the five candidates from the sample project. The candidates are sorted first by the crash length, so you can see the tasks that shorten the schedule the most. Then they're sorted by cost per day, so you can pick the most cost effective candidates. In this case, the first three candidates shortened the schedule by five and a half days. Total crash cost is $2000. In comparison, if you crashed revised content through layout employee handbook, the schedule would be five days shorter, but the crash cost would increase to $2600.
So, let's see what happens to the schedule when we crash the first three tasks. Here is the schedule before crashing. The project finish date is December 31st. After changing edit content to seven and a half days, review content to three days and revise content to three days, the project finish date changes to December 24th. Five work days earlier. If the project still needs to be shorter, repeat these steps, starting with reexamining the critical path.
That's because you need to make sure that the next task to crash is also on the critical path. If the finish date is more important than the price tag Crashing tasks is an effective way to shorten the schedule
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- Identifying the work that needs to be done
- Adding milestones
- Delaying or overlapping tasks with lag and lead time
- Assigning resources
- Balancing workloads
- Adding buffers and baselines to the schedule
- Uncovering and correcting out schedule problems<br><br>
- The PMI Registered Education Provider logo is a registered mark of the Project Management Institute, Inc.