Lecture - 1
Building Blocks for Planning
In order to understand construction planning, it is first important to have a preliminary understanding of projects.
1a. Introduction to Project Management
Projects are unique endeavors with a specific beginning and end. Differences will exist between any two projects. Consider the case of two similar small-scale residential buildings. Differences can arise in soil conditions, interior design, selection of contractors and so on. As a result, projects are 'learning impaired' - it is very difficult to translate knowledge gained or learnings from one project directly to another, due to the inherent differences across projects. This is in contrast with 'processes' that are followed in the manufacturing and other industries, that are repetitive and where a learning curve often results in improved performance over time.
While there are a number of project-based industries, the Architecture-Engineering-Construction (AEC) industry stands out both in terms of the size of projects undertaken (costs of construction projects are extremely high - even a small residential tower can easily cost Rs. 50 Crore), as well as the organizational complexity of executing these projects. The construction industry is highly fragmented and as a result, a number of different organizations are involved in executing a construction project ranging from design firms, consultants, main and subcontractors, vendors and so on. Given the challenges in coordinating amongst these agencies, the process of managing construction projects is highly complex.
Planning therefore plays a critical part on construction projects. Effective planning helps practitioners anticipate challenges and deal with them early on in a project, where the amount of money expended is low, and the flexibility of making an intervention is high. As the project progresses, changes are more expensive to make and budgets are often depleted, and as a result course corrections are not possible. It is for this reason, that considerable attention must be directed towards the planning process in construction projects.
1b. Work Breakdown Structures
Once a project has been awarded, the planning process can begin. The first task is to identify the various activities to be executed on the project. Once this is done, detailed construction methodologies for each of these activities should be identified. Once the methods are fixed, the resource requirements for each activity corresponding to these methods can be ascertained. Based on the productivity of the resources available (or chosen), durations for each of the activities can be calculated. Simultaneously, relationships between activities can also be fixed. These are the basic building blocks of creating a project plan.
The first and most important task, therefore, is to develop a detailed list of activities to be executed on the project. This is known as a Work Breakdown Structure (WBS). All other planning steps follow directly from the WBS, and therefore if the WBS is inconsistent or not comprehensive, then it is likely that a planning or execution failure will occur later on in the project. Normally, when developing a work breakdown structure, planners tend to think mainly of engineering activities. These are activities such as excavation, casting foundations, casting slabs and so on. While these are a vital part of the planning process, other kinds of activities or tasks must also be included in the WBS. These tasks can be grouped under the following categories
- Procurement of Materials
- Procurement of Equipment
- Preconstruction activities (e.g. procuring permits, insurance etc)
- Post-construction activities (e.g. commissioning, housekeeping etc)
Procurement of materials includes placing purchase orders, testing samples and so on. Procurement of equipment involves renting or purchasing equipment, transporting it to the project site and so on. Pre-construction activities range from obtaining the necessary permits to building approach roads and temporary structures, while post-construction activities relate to site clean-up, commissioning the structure and so on. These are all vital activities for which planning is needed. For instance, if a particular material has a long lead time, the purchase process must be carefully monitored. It therefore follows that this process must also be carefully planned, and therefore the set of activities relating to the procurement of this material must be made a part of the WBS for the project. A comprehensive and useful WBS that can guarantee good project performance will therefore feature activities within the above categories in addition to engineering activities.
1c. Bar Charts
Once a detailed WBS has been established, construction methods can be fixed, resources can be estimated and durations as well as activity relationships can be set. Once these preliminary planning activities are done, the most simplistic way of representing a project plan is through the creation of a Bar Chart, also known as a Gantt chart (named after Henry Gantt who is credited with developing this tool).
Most construction planners and engineers are very familiar with bar charts. As shown in the slides, a bar chart consists of a set of activities listed vertically one below the other. On the horizontal axis runs the projects timeline starting from the planned start date up until the planned finish date. Each activity is then represented as a 'bar' under this timeline. The bar starts from the planned start date of the activity and continues up until the planned finish date of the activity. Activities in the bar chart are listed in increasing order of their planned start dates and bars are drawn to scale, such that an activity whose bar is twice as long as another's can be said to take twice the time.
While representing activities in a bar chart, it is very important to note that a bar denotes an activity that is continuously performed. Therefore, when an 'excavation' activity is shown for a duration of, say, 15 days, the expectation is that the activity is performed continuously over 15 days. If on the other hand, the plan is to excavate two areas for 5 days each with a gap of 5 days in the middle, then this should be represented as two separate excavation activities in the bar chart.
Other kinds of information can also be represented in the bar chart. For instance, the person in charge of each activity can be show next to the activity. The status of the activity can also be shown using pre-determined symbols. The progress of an activity can also be shown by shading a portion of the bar in proportion to the actual percentage of the activity that has been completed. Running a vertical line through the chart on any given day can give a quick view of the activities to be performed on that date.
Bar charts possess several advantages and disadvantages. On the one hand, bar charts are simple tools, easy to create and offer a simple visual picture of how the project will be undertaken. This can be understood by a number of stakeholders including laborers on site. However, on the other hand, bar charts with large numbers of activities become very complex to read and interpret. Further, the relationship between activities is not explicitly represented in a bar chart. Therefore a person reading the bar chart will need to understand the logic used by the planner to understand the impacts to the plan if there is a delay in any given activity. These make bar charts highly difficult to use in large complex projects. However, they may be quite useful when projects are small and relatively routine in nature. Alternatively large projects can be broken into small sub-projects, within which bar charts can be used.
In the next chapter, we attempt to understand how these limitations of bar charts can be overcome through the use of other planning tools.