3 METODOLOGÍA
3.6 Tabulación de los datos de la encuesta
The critical path should not be a surprise. Don’t overlook your common sense and con- struction experience. The critical path or paths should be where you would expect them. Also check the near critical path, the paths or strings of activities with a small amount of shared float. Are the near critical activities about as you would expect them? Again, don’t get so tied into the computer and the calculations that you overlook your common sense based on experience.
Milestones
Are the project milestones (major achievements) about where you would expect them? Think of the project in big chunks. For example, on a commercial building project think of the following: Is the project duration about right to get from the excavation to the completed foundation? Is the duration from the foundation to the finished structure about right? Is the duration on course for all the interior rough-ins? Is the duration accurate for the amount of time scheduled for all the exterior finishes? the interior finishes?
Procurement
Has the schedule included the key items of procurement? Double-check, especially the items that have a long lead time. Should they be included as part of the schedule? Think of past projects where procurement items have created problems and make sure those items are taken care of. Make sure the critical path activities receive their materials just prior to the installation of those materials. Materials delivered to the job site too early incur damage and possible theft. Check to make sure the procurement activities do not consume all the float shared with other construction activities, making those other activities critical.
Time of Year
Double-check the activities that must be done during a particular time of year. Will it be too cold or too hot for the seasonal activities? If temporary heat must be provided, it might be a good idea to make it part of the schedule so that it is not overlooked. Is special weather protection needed during part of the construction process? Will it be necessary for some activities to be accelerated to make sure weather-sensitive activities are completed prior to bad weather?
Float Paths
Check the paths or strings of activities that have large amounts of float and see if that is really the case. Do those activities actually need to be completed prior to the start of other activities? Do you want to show that much float, or could you finish that part of the project and lock it off, or get the punch list items done in that area and then make that area off-limits? When a path or string of activities share float, it is not a bad idea to increase their activity duration in order to share that shared float. Take the pressure off those activities. However, save some of the shared float in case future problems arise.
FIGURE 11.4 A highway overpass project schedule with crane activities color-coded
Organize to Simplify
Is there any way you can reorganize the schedule to simplify it or make it communicate better? Ways to simplify include listing all the activities for one area together on the logic diagram; scheduling the activities in order from top to bottom—for example, the roofing activities would be on the top of the diagram and the footings and foundations on the bottom; showing floor levels from the bottom to the top as the building is being completed, or in reverse sequence as long as they are grouped together; with highway or lineal construction, showing the mile mark- ers or other things to consider to make the schedule appear more organized and easy to follow. Color-Code Some Activities
Would color-coding of key activities help the schedule? Having each trade represented by a specific color? Or showing a specific color for each activity that requires a particular piece of equipment, person, or other key resource? Would the schedule communicate better if a specific color was used to identify each inspection?
Figure 11.4 shows a portion of a highway overpass schedule where the activities that use the crane are highlighted by the darker colored activity box. Having the crane activities stand out helps in evaluating the schedule to make sure it is realistic in its use of the crane.
Chapter 11 • Reviewing and Analyzing the Schedule 107
Application
1. Go back to the warehouse project you scheduled in earlier chapters, double- check the items discussed in this chapter, and record changes made. Was the review worth it? Is the reviewed schedule better than the original schedule?
2. Make a checklist of activities where an improper sequence caused quality prob- lems. Keep this list and keep adding to these activities as you manage projects. Then you can consult this list on future
schedules to make sure you will not expe- rience those problems again. If you are a student and have not had sufficient expe- rience to do this, interview an experienced project manager for this information. 3. Follow the same instructions as for activ-
ity 2, but focus on issues relating to safety. 4. Look at your warehouse schedule and con- sider cutting two weeks off the schedule. How would you do it to cause the least negative effect on quality, costs, and safety?
Conclusion
The management team must review and analyze the schedule before communicating it to the subcontractors and workers and anyone else involved in the project. The team should ask themselves these questions as they review the schedule: (1) Does this activity really need to be done before each of the following activities can start? (2) What other activities should take place before this activity can start? Managers must also review the activities and logic relationships to ensure that the working conditions are safe and that all activities will be done in the proper sequence to maintain high-quality standards and keep costs at a minimum. If a schedule is too long or goes beyond contract completion date, or there is a need to decrease congestion at the job site,
managers have the option to either compress or expand the schedule using various methods. Throughout the project, managers need to con- stantly assess such factors as durations, procure- ment, the weather, float paths, and schedule organization in order to maximize their success.
Many major problems on construction proj- ects are traceable to poor planning. Reviewing and analyzing the schedule will eliminate many potential problems. It does take a few minutes to double-check but it is worth the time. Remember, it is easier to erase on paper than to remove concrete and welds. Let’s eliminate the old say- ing, “There is never time to do it right but there is always time to do it over.” Schedule and plan to do it right the first time.
108
INTRODUCTION
The network logic diagram forces the management team to think through the project in detail and then the diagram communicates that thinking and planning to all involved in the project—provided they have been taught to read and understand the logic diagram. This is a major problem with CPM networks. The typical field workers have had no train- ing in reading logic diagrams. They see the logic diagram as a confusing bunch of arrows, boxes, and way too many numbers. When field workers, and many times managers, hear the word “schedule,” they automatically think of a bar chart, not a network logic diagram. Bar charts are the default schedule that most people think of, but they lack the detailed information and clarity of network logic diagrams. Plus, as a bar chart is updated and the schedule falls behind in an area or two, the manager must rethink the future schedule based on what has been done. However, with CPM scheduling the updated future activi- ties are automatically adjusted based on the logic diagram.
How do we overcome this problem? The answer is to plan the project using CPM and then print bar charts or even tabular reports on the computer to communicate the schedule to those who would prefer simpler scheduling methods. This chapter will take the power of the CPM network logic diagram and create a bar chart using that detailed