A linear bar chart is a type of bar chart that has been developed and created by the author. It is particularly well suited for repetitive elements in projects, such as the inte- rior finishes in a multistory office building. A linear bar chart is also useful for repetitive projects such as homes or multiunit housing projects. Similar to the standard bar chart, the linear bar chart is also based on the network logic diagram. There is no current soft- ware on the market that creates this type of bar chart. For project management teams who are not computer oriented, it may be an ideal method of planning and scheduling the project.
The linear bar chart is created from a logic diagram. Therefore, the first step is to cre- ate the logic diagram.
Figure 12.12 is a logic diagram of the interior finishes for one floor of a small office building. The critical path activities are bolded. Notice that Rgh. Mech. has 1 day of inde- pendent float and Floor Coverings and Finish Mech. have 2 days of shared float.
The next step is to create the linear bar chart showing the schedule information, as shown in Figure 12.13.
Chapter 12 • Creating Bar Charts and Tabular Reports from Network Logic Diagrams 117
Inst. Studs Rgh. Elect.
3 3 0 3 3 6 Drywall 4 6 10 Floor Coverings 2 17 15 Finish Carpentry 2 12 10 Paint 3 15 12 0 3 0 3 0 6 6 0 10 10 0 12 12 0 15 Finish Elect. 5 20 15 Floor Complete 0 20 20 0 20 15 20 0 20 Rgh. Mech. 2 5 3 2 19 17 Finish Mech. 1 18 17 2 20 19 1 6 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Inst. Studs Rgh. Elect.
Rgh. Mech.
Drywall Carpentry Paint Finish Electrical
Floor Cover F./ Mech.
FIGURE 12.13 A linear bar chart based on the logic diagram in Figure 12.12
The critical path is the first line of activities with the bolded bars end-to-end. If there are multiple critical paths, those additional critical activities are drawn attached to the bottom of the first critical bar activities. The duration can be determined by comparing the individual activity bar with the time scale on the top. Float is shown by the multiple horizontal lines. Shared float is shown by placing the activity bars that share float end-to-end and then showing the shared float after the last activity as in
Floor Cover and F. Mech. Independent float is shown by locating that activity all alone
as in Rgh. Mech. The resulting bar chart is called a linear bar chart because the activi- ties’ bars are aligned in a linear rather than vertical fashion as in the case of a standard bar chart.
Many managers would feel comfortable giving the linear bar chart to subcon- tractors because it shows both the activities with shared float and the activities with independent float. Consequently, it is less likely that a subcontractor would think that the shared float belongs to his or her activity alone and, therefore, would misuse the float.
The linear bar chart takes on additional power when it is used in a master schedule for the construction of repetitive activities. A master schedule of the interior finishes in a four-story office building could be created as shown in Figure 12.14.
Each floor level appears as a single bar in this linear bar chart schedule. The floor lev- els are offset by 5 days because the longest critical duration is 5 days. This provides for a schedule where the crews could go from floor level to floor level without having any crew scheduled to be in two places at one time.
The schedule could be updated by hand using a highlighter to show progress on each bar where progress has been made. If this schedule is mounted on a wall or bulletin board, a string with a weight on the bottom (like a plumb bob) could be tacked on the time scale representing the current day, and then progress could be noted by comparing the highlighted activities with the position of the string. If each floor level bar was printed on a separate piece of paper, that long, narrow piece of paper could be moved to the right or left to update the schedule in comparison with the string representing the current day.
The linear bar chart can be updated and scheduled by hand quite easily. There are no software programs that can create this linear master schedule from the CPM infor- mation input into the computer. The linear bar chart is most easily made by using a spreadsheet program such as Microsoft Excel. The master linear bar chart schedule works well with repetitive projects such as units, floor levels, houses, buildings, or
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Inst. Studs Rgh. Elect.
Rgh. Mech.
Drywall Carpentry Paint Finish Electrical Floor CoverMech.F./
1st Floor
Inst. Studs Rgh. Elect.
Rgh. Mech.
Drywall Carpentry Paint Finish Electrical Floor CoverMech.F./ 2nd Floor
Inst. Studs Rgh. Elect.
Rgh. Mech.
Drywall Carpentry Paint Finish Electrical Floor CoverMech.F./
3rd Floor
Inst. Studs Rgh. Elect.
Rgh. Mech.
Drywall Carpentry Paint Finish Electrical Floor Cover Mech.F./
4th Floor
FIGURE 12.14 There is a separate linear bar chart for each floor level in this four-story office building schedule
FIGURE 12.15 SureTrak Project Manager network logic diagram for the warehouse project
apartments. The updated master schedule would show the current status of the project and precisely which activities are ahead of or behind schedule. If this master linear bar chart schedule is located in a highly visible place, it puts subtle pressure on everyone to adhere to the schedule.