Jim lists the steps required in the process of creating a scheduling network model, and describes each step. Jim explains that the first step is to define work activities on the construction project, which was done using the WBS.
- My next step in this ongoing planning and scheduling process is to develop what we call a network model. The idea here of network-based planning is that I want to develop a network that represents a time-oriented model of the project. How do I do that? Well, we already started. Step one was to define our activities and that's what we started in the work breakdown structure. The other steps look like this. Order those activities. Establish activity relationships and draw a network diagram.
Assign durations to the activities, and then I might also assign resources and costs. Then, I need to calculate early and late start and finish times. I'll use those to compute float values and then identify the critical path. Then, I can schedule activities start and finish dates. I want to address step five, that I said was assign resources and costs. This is a step that is not always used in the construction scheduling process, but it can really be helpful on larger projects to manage everything from equipment to cashflow.
I will say that I think assigning resources and costs is really only made useful when you are using software that helps manage this information. Scheduling software like Microsoft Project will let you include resources which could be things like equipment, into a schedule. When you assign one of these resources to an activity, the software then can help you identify potential conflicts that could occur if two activities are scheduled to use the same piece of equipment at the same time.
That brings me to another point. It's important to recognize that creating this network model is usually an ongoing or an iterative process on a construction project. As we follow these ordered steps using the activities we've identified, it's common to find conflicts that require steps to be reordered or activities to be adjusted. When we're all done creating this model though, it should be a really good representation of how the project will actually progress, otherwise it's not going to be used as a management tool.
Now speaking of using this as a management tool that does remind me that we're not quite done with step one yet, which was defining our activities. Our work breakdown structure gave us our construction activities, but I might need to go in and add some management activities and procurement activities. What I'm talking about here are really some things that may be hidden within those construction activities in the work breakdown structure, but I may want to pull those items out and list them separately if they're going to impact the schedule.
Let's talk about procurement activities first. I'm talking about things that I may need to order, particularly long lead time items that will impact my schedule if I don't get them ordered on time. Things like structural steel, reinforcing, some custom-built mechanical equipment, or elevator control panels. These are all things that might have to be fabricated specifically for this project, and if so, I need to identify them and get them on the schedule. My street improvement work used to really be impacted by the traffic signal poles of all things.
These were always custom-built for each job and they had to be hot-dip galvanized, which really just means that they took me at least 12 weeks to get. If the only item I had on the schedule for traffic signal poles was that one item near the end of the schedule, the project management team might not realize that this hardware needed to be ordered at the start of the project. Same thing goes with management tasks. If I have items and things that might have to be fabricated, that may also mean that I have to produce shop drawings that detail the fabrication.
Those shop drawings could take days or even weeks, and then they have to be submitted for review and approval before fabrication can even start. On my schedule, I want the shop drawings as an activity, actually I want two activities, one for producing the shop drawings, which is under my control as the contractor, and another item for reviewing the shop drawings, which is usually out of my control because the design team does this. So, why put it on the schedule like that? Because I want to visually show the entire construction team, the owner, the architect, the project managers, and the subcontractors, the affect that these drawings can have.
If I can't start fabricating the structural steel for the building until these are approved, they're in the critical path. I want the designer to know when they should expect to have these drawings and how long we expect it to take them to review. If they take an extra week or two for review, I need to be able to update my schedule and I want to illustrate where this delay took place. Now, I know it may seem as I'm talking here that I expect this network model to be a perfect schedule for the job, but I know that's rarely going to happen.
I do expect to revisit and revise this model as the project progresses, as we find scheduling constraints we didn't know about, change orders are issued, or as manpower and productivity fluctuates. I'll talk about keeping this network updated a little later. Right now, since we've completed step one, and we've now defined all of our activities and put them in a list, let's move to the next step and start creating that network model.
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