In this video, Jim explains the process of assigning durations to each of the activities in the scheduling network for the sample construction project. He also discusses the importance of assigning accurate durations.
- At this point in the process, we've defined our items, we've ordered our items, and we've modeled the relationships. Now, we have to assign a duration to each activity. Of course, this is one of those magical mystery numbers that can make our schedule look like it works, or not. And, that's always the million dollar question on a construction project, which is, how long is this going to take? To answer this, you might do things like use historical data if you have that available. That could be your own company's historical data, or it could be from an industry guide like RS Means that gives typical production rates for lots of different types of work.
If you're self performing the work, you may have accurate productivity rates for different activities that you can apply to the quantities on this project. Keep in mind though, that you may need to confer with your field personnel or your field supervisors. If you're sub-contracting the work out, you may want to talk to the sub-contractors and get their input on the durations that they anticipate for their activities. You want to be as accurate as possible here and not just throw out numbers. If you really believe that an activity is going to take 15 days, it really doesn't do any good to cut out three days just to make the schedule look better or to make it hit a certain target date unless you can justify why you took the days out.
Remember, we're trying to create a useful schedule. One that tells us when each activity will start so that we can schedule crews, and equipment, and sub-contractors. When it comes to estimating durations, it will obviously pay to get input from experienced personnel. In order to continue on and create the actual schedule you have to assign durations to every activity. At this point, you can also assign resources and costs like I talked about earlier. The assignment of resources and costs to a schedule is a great way to make the schedule an even more powerful management tool.
But it is a topic that is a little beyond the scope of this course. Right now, we just want to get the schedule built. And as long as we have all of our durations assigned, we can do that by continuing on to the next step of calculating early and late start and finish times.
This course identifies the steps needed to develop a proper plan, and demonstrates how that plan is transformed into a construction schedule. Throughout the course, instructor Jim Rogers shares examples of his own successes and failures in the areas of construction planning and scheduling, so as to lend real-world context to the concepts he covers.
- Types of schedules
- Planning versus scheduling
- Work breakdown structure
- Developing a schedule
- Creating a network model
- Assigning durations, costs, and resources
- Identifying the critical path
- Letting the software do the calculations
- Checking and updating the schedule
- Scheduling's impact on productivity