Chapter-7# Project Controlling and Scheduling

Transcription

1 Chapter-7# Project Controlling and Scheduling 7.1 Meaning of Project Controlling (PC) PC is concerned with the optimum use of the total resources of an organization to meet the technical, cost and time constraints of the project. The prime responsibility of a project manager in view of project implementation and control may be grouped in the following four categories. Theses activities are known as mechanism or steps of project control. These are: i. Routing ii. Scheduling iii. Dispatching and iv. Follow-up 7.2 Project Scheduling The project schedule is the tool that communicates what work needs to be performed, which resources of the organization will perform the work and the timeframes in which that work needs to be performed. The project schedule should reflect all of the work associated with delivering the project on time. Without a full and complete schedule, the project manager will be unable to communicate the complete effort, in terms of cost and resources, necessary to deliver the project. Project planning answers the questions What is going to be done? How? Where? By whom? and When? Scheduling deals with when on a detailed level. 7.3 The Scheduler The scheduler: A civil engineer, an architect, a computer whiz, a mathematician, a project manager, an artist, or a communicator? An increasing trend-in all industries- is to use computer software and other high-tech tools. These software packages cover the entire spectrum of all industries, including some generic types of software, such as word processors and spreadsheets that everyone uses. However, specialized software requires knowledge of both the software and the discipline. Scheduling is no exception to this rule. Let us distinguish among three types of knowledge that a scheduler must have: 1. Knowledge of computer software. 2. Knowledge of the principles of scheduling and project control. 3. Knowledge of the specific technical field, such as commercial building, industrial, transportation, and so forth. 7.4 How to Build a Solid Schedule Schedule compression is a common term in the practice of project management today. The project schedule is scrutinized regularly in the interest of staying on budget and getting the product or services to market. By creating a solid schedule at the start of the project, project managers can help curb cost overruns, resource shortages or excessive change requests. Here, a panel of project scheduling professionals offer seven tips for creating a solid project schedule. Lecturer, DBA, IIUC, website: 1

2 1. Realize the importance of the schedule. Project managers and the project management team often do not put enough emphasis on the schedule. However, a good schedule touches every Knowledge Area and process group of A Guide to the Project Management Body of Knowledge(PMBOK Guide). For example, if a potential slip in the schedule is identified, the project manager would address it through the project's issues and risks processes. Schedule changes can affect any area of the project and can have downstream impacts. In this manner, the schedule becomes the central focus and the foundational tool for managing the project. 2. Identify the availability of team members. A resource inventory is needed to plan the whole project and to decide which path you will take to execute the project. Who will be available to work on the project? Are there any holes or will any team member be stretched too thin? This is especially important in environments where budgets are tight and many organizations hesitate to take on more staff members. Once the project team has been established, ask for their input on the schedule to ensure it is reasonable. 3. Build the schedule around deliverables. It is human nature to want to build a schedule around tasks, but that method can cause problems. The flaw with that approach is that a scheduler cannot easily tell if a stakeholder change is actually within the project scope. Project schedulers should build the schedule around deliverables because they are tangible, verifiable and must meet predetermined standards to be complete. 4. Include regular milestones. Establish milestones within the schedule and check those milestones frequently. That way, if a project lasts for eight months, you do not get to month four and realize you are going to be late. If you miss milestones that occur in the first couple of months of the project, you know whether the project is on schedule. 5. Expect that the schedule will change. Realize that the schedule is not permanent because project tasks and stakeholder needs constantly fluctuate. The project schedule is really an assumption about what might happen and when. It is your job to continue to understand the reason for any variances and make appropriate changes to the schedule to meet the changing project landscape. This would include a contingency plan. 6. Have a process for managing change. Project managers must be willing to shift gears to help a project stay on track. Establish a Lecturer, DBA, IIUC, website: 2

3 threshold that triggers the change-control process. For example, if a proposed change would make the project more than a day late, the client or a change-control board must first approve it. However, be cautious against making changes out of scope. 7. Watch for hangers. A basic scheduling rule is that every task should have at least one predecessor and at least one successor. The obvious exception is the project start milestone, which has no predecessor, and the project complete milestone, which has no successor. When a task lacks a predecessor and/or successor, the task has a hanger, which is an unintended break in the project network diagram. The problem is that the forward and backward pass calculations will be incomplete and possibly wrong because each hanger results in a roadblock for critical path method calculations. 7.5 The Reason for Scheduling There are several parties involved in any project. They all need and benefit from project scheduling but from different perspectives. Following is a group of reasons for why project scheduling is needed, from two different perspectives: contractors and owners. Contractors need project scheduling to: a. Calculate the project completion time: In most construction projects, the general contractor, including subcontractors and other team members, is obliged to finish the project by a certain time specified in the contract. The contractor has to make sure that his or her schedule meets this time. Some contracts contain clauses for penalties for finishing the project later than contractually required and / or incentives for finishing earlier. Also, the schedule may show the stage of substantial completion, when the owner may start occupying and using the facility while the contractor is still doing some final touches. b. Calculate the start or end of a specific activity: Specific activities may require special attention, such as ordering and delivering materials or equipment. For instance, the project manager may want special and expensive equipment to be delivered just in time for installation. Long lead items may have to be ordered several months in advance. Delivery of very large items need coordination or a special permit from the city so that such delivery does not disrupt traffic during rush hour. The schedule must show such important dates. c. Coordinate among trades and subcontractors, and expose and adjust conflicts: In today s construction, the general contractor s role is mostly to coordinate among different subcontractors. The responsibility of the general contractor may be to allocate the time of use of a tower crane among subcontractors or just to ensure that adequate work space is available for all subcontractors. These tasks are in addition to coordinating logical relationships such as when a subcontractor s activity depends on the completion of another subcontractor s activity. For example, the drywall contractor cannot start until the farming has been done; once the drywell is installed, the painter can start painting; and so on. Lecturer, DBA, IIUC, website: 3

4 d. Predict and calculate the cash flow: The timing of an activity has an impact on the cash flow, which may be an important factor for the contractor to consider. The contractor must know his or her total spending in any month or time period. He or she may delay the start of certain activities, within the available float to make sure that the cash flow does not exceed a certain cap. e. Improve work efficiency: By properly distributing workers and equipment and having efficient materials management, the general contractor can save time and money. f. Serve as an effective project control tool: Project control must have a solid and sound base with which current performance can be compared. Project control is achieved by comparing the actual schedule and budget with the baseline schedule and budget. g. Evaluate the effect of changes: Change orders are almost inevitable, but well-planned projects may have few or minor change orders. Change orders may come in the form of directive, that is, an order to the contractor to make the change, or request for evaluation before authorization. This change may be an addition, a deletion, or a substitution. Change orders may have an impact on the budget, schedule, or both. Cost estimators estimate the cost of change orders, but schedulers calculate the impact of the change on the project schedule. It is the contractor s responsibility to inform the owner on such impact and obtain his/her approval on the change to the budget and/or schedule. h. Prove delay claims: Construction delay claims are common. Contractors must be able to accurately prove their claims against owners using project schedules. In most cases, only a critical path method schedule can prove or disprove a delay claim, which can be a multimillion taka one. Project owners and developers need project scheduling to: a. Get an idea on project s expected finish time: Before an owner demands that the general contractor complete the project by a certain time, he/she needs to make sure that this is a feasible and reasonable time. This tie is calculated by a CPM schedule prepared either by the owner or by the designer or other consultant hired by the owner. This time is also important to the owner, even before selecting a contractor, to conduct feasibility studies and financial planning. b. Ensure contractor s proper planning for timely finish: Owners may demand a project schedule from the prospective or bidding contractor, however, it is very important for the owner to review such schedule and make sure that it is reasonably accurate and realistic. Owner s approval of contractor s prepared schedule may imply a liability on the owner s side. c. Predict and calculate the cash flow: The owner is obliged to make timely progress payments to the contractor and other parties along the life of the project. Failure to do so not only may delay the project and/or incur additional cost but it also may-at certain point-be deemed a breach of contract. Lecturer, DBA, IIUC, website: 4

5 d. Serve as an effective project monitoring tool: Both owner and contractor must monitor progress of work and compare actual progress with the baseline schedule and budget. The contractors use this process to detect and correct any deviation and also to prepare progress payments. The owner uses process to verify actual work progress and contractor s payment request. e. Evaluate the effect of changes: Owners may desire or require change orders. In many instance, owners don t expect or fully appreciate the impact these changes orders may have on the schedule and/or budget. It is a wise idea for an owner to find out this impact before making a decision regarding such change order. It also recommended that owners analyze the contractor s assessment of the change order to make sure that it is fair and reasonable. f. Verify delay claims: Owners use CPM schedules to analyze, verify, and/or dispute contractors delay claims. Although most delay claims are initiated by contractors against owners, it is possible to reverse roles and an owner s claim against the contractor or, and/or have other parties involved. In either case, a CPM schedule is vital for the owner to prove his/her case. Other parties involved in the project may also need a CPM schedule, such as the designer, project management consultant, and financial lending institution. 7.6 Project Schedule Tools & Techniques The project schedule is the time-based and/or sequenced description of all of the project activities. The time element is one of the triple constraints that every project leader must contend with: scope, schedule, and resources/budget. There are a variety of techniques for both displaying the project schedule and analyzing the project schedule. Each technique focuses on a different aspect of the project. Depending upon the project objectives and major risks, different techniques should be used by the project leader. A brief description of each technique is listed below along with suggestions for when, and when not, to use them. The techniques for displaying the schedule are the Milestone Chart, the Task List, the Gantt Chart (Bar Chart), the Network Diagram, the Two Dimensional Task List, and the Calendar View. The schedule analysis tools are the Critical Path analysis, the Critical Chain analysis, the PERT analysis, the Resource Leveling analysis, and a variety of Schedule Acceleration Techniques. i) Milestone Chart The milestone chart is portrayed on a project time line. It displays only the key project milestones. These milestones are typically associated with some major element of project risk, such as passing a test or gaining approval from a regulatory agency. Each milestone is represented by a diamond or triangle. These milestones normally become major reporting points to senior management. Large complex projects may have hundreds or even thousands of tasks. Senior management usually does not want to receive status reports at that level of detail, yet they want something more than just altogether review at the end of a phase. The milestones provide interim reporting points. Also, when planning a complex project, task leaders can become overwhelmed with all the tasks they must do. Having a focused sub-project for each milestone gives those task leaders a framework for planning and tracking project activities. Lecturer, DBA, IIUC, website: 5

6 Project milestone schedules contain such information as: Project start date Project end date Other major milestones Data items (deliverables or reports) ii) Task List The Task List is the simplest of the schedule format tools, yet it can be the most powerful and useful tool with extended members of the project team. A Task List is just an action item list for the team member that contains all of the tasks that individual is responsible for completing. This provides a focus for the individual as to what they need to do. This format works very well with extended team members on large projects. In those cases, the project may contain hundreds of tasks but often the extended team member is only involved in a small number of those tasks. The extended team member can review their task list and understand what they must do on the project without going through the hundreds of tasks, searching for those requiring their effort. If the team has many extended team members with limited involvement in the total project, this technique usually is the best method for communicating and tracking scheduling of the work from those extended team members. iii) Bar Chart (Gantt Chart) A bar chart is a graphic representation of project activities, shown in a time-scaled bar line with no links shown between activities (Popescu and Charoenngam 1995, p. 96). The bar chart was originally developed by Henry L. Gantt in 1917 and is alternatively called a Gantt chart. It quickly became popular-especially in the construction industry on a time scale. On a bar chart, the bar may not indicate continuous work from the start of the activity until its end. For example, the activity Getting a Building Permit may be represented by a 2-month-long bar. However, most of this time is a waiting period. Likewise, a Concrete to cure. Noncontinuous (dashed) bars are sometimes used to distinguish between real work (solid line) and inactive periods (gaps beween solid lines) (Callahan, Quackenbush, and Rowings 1992). Bar charts have become a vehicle for representing many pieces of a project s information. Many variations of bar charts have evolved; some simply show the start and end of each activity (Figures 2.1 and 2.2), some are loaded with resource or budget numbers (Figures 2.3 and 2.4), and others compare the as-planned schedule with the as-built schedule (Figure 2.5). Using Primavera Project Manager (P6) software (Recently acquired by Oracle), we can show activities with interruptions as continuous bars or as necked bars (Figure 2.3). Since bar sharts basically use the x- axis only (to depict time), the y-axis is used (in addition to showing individual activities) to represent a variable across time, such as man-hours (Figure 2.4), budget (Figure 2.5), percent complete (Figure 2.6), and so forth. This variable is usually shown as a curve superimposed on the bar chart. In Figure 2.5, S curves (also called lazy-s curves) represent the percent on extrapolation from the as-built curve. Lecturer, DBA, IIUC, website: 6

7 Figure 7.1: Bar chart for placing a simple slab on a grade iv) Basic Networks A network is a logical and chronological graphic representation of the activities composing a project. Network diagrams are basically of to types: arrow networks and node networks. Arrow networks were more popular in the 1960s and 1970s, then precedence diagrams became the choice for network scheduling. a) Arrow networks Arrow networks are also called the arrow diagramming method(adm), activity on arrow (AOA) networks, or the I-J method (because activities are defined by the from node, I, and the to node, J) b) Node Networks Node networks are also called activity on node (AON) networks. In node networks, we use a different notation for representation: a node represents an activity. Nodes are connected with arrows that represent the logical relationships. There is no need in the node diagram for dummy activities. A scheduling novice can draw a node diagram much more easily than an arrow diagram. For aesthetic reasons only, we like to start any network with one node and end it with one node. Doing so many require one or two fictitious activities in node diagrams that start or end with more than one activity. We call these activities PS (Project Start) and PF (Project Finish), displayed as diamond-shaped nodes. B D A E v) 2-D Task List The 2-Dimensional Task List is only needed C occasionally. However, in those situations it both simplifies planning and tracking while improving the ability of the project manager to manage many of the project tasks effectively. This technique is used for scheduling and tracking a large quantity, or batch, of items through the same set of project tasks or activities. The 2-D task list is a matrix with the vertical side being a list of the items in the batch and the horizontal being the set of tasks. The planned date for task completion of Lecturer, DBA, IIUC, website: 7

8 each item through the set of tasks is set in the corresponding box of the matrix. As a task is completed, normally the background color of the cell in the matrix is changed so that it shows completion. This change in color allows the project manager to quickly see when one item in the batch starts to fall behind or when many items in the batch become bottlenecked at one step in the set of tasks. vi) Critical Path Method (CPM) The Critical Path method is used to determine what the shortest time is to complete the project, or a phase of the project. The method analyzes every possible sequence of tasks based upon the network diagram to determine which sequence is the longest. This sequence is called the critical path because it sets the minimum time in which the project can be completed. A caution when using critical path it assumes that you have all the resources you need at all times. This is seldom a valid assumption, so the minimum time indicated by the critical path is seldom actually achieved on a project. To determine the critical path, the network diagram is created for the project with the maximum amount of parallel task as your risk sensitivity can tolerate. Each task duration is estimated, assuming the task will have the desired resources available when needed. With the durations and relationships from the network diagram, calculate first the earliest possible start date and finish date for each task. Then using the calculated project finish date, determine the latest possible start and finish date for each task that still supports that date. This set of calculations is normally done by project management software. The sequence of tasks with identical dates for early start and latest start are the critical path. The tasks have no float or slack a one day delay on one of these tasks immediately translates into a one day delay on the project. 7.6 Quantitative Problems: Problem # 1 Find below a number of activities along with their required completion times: Activities A B C D E F G H I Duration (day) Immediate predecessors A A, B -- B, E F C, D G, H Required: a. Draw a Gantt Chart. b. Find out slack for each activity (total slack) c. Show the Critical Path. d. How many days will it take to complete the project? Problem # 2 Find below a number of activities along with their required completion times Activities A B C D E F G Immediate - - A A,B - C,E,D F predecessors Duration (weeks) Lecturer, DBA, IIUC, website: 8

9 Required: i. Draw a Gantt Chart ii. Show the critical path iii. How many days will it take to complete the project? Problem # 3 For a small project of 12 activities, the details are given below. Activities A B C D E F G H I J K L Dependences B,C A C E E D,F,H E G,I,J K Duration(days) Required: i. Draw a Gantt Chart. ii. Find the critical path and iii. Find earliest occurrence time, latest occurrence time, critical activities and project completion time Problem # 4 You are given below a table showing activities, their required sequence, and time requirements for the new introduction project. Activity Description Immediate Predecessor Time Code Activity (Weeks) A Organize Sales Office B Hire Salespeople A 4 C Train Salespeople B 7 D Select Advertising Agency A 2 E Plan Advertising Campaign D 4 F Conduct Advertising Campaign E 10 G Design Package H Set-up Packaging Facilities G 10 I Package Initial Stocks H, J 6 J Order Stock from Manufacturer K Select Distributors A 9 L Sell to Distributors C, K 3 M Ship Stock to Distributors I, L 5 Required: a. Identify different paths in the network showing critical path. b. Find out slacks of each path. c. How many weeks will it take to complete the marketing operation? Lecturer, DBA, IIUC, website: 9

10 Problem # 5 A project consists of eight activities with the following relevant information: Activity Immediate Estimated duration(days) predecessor Optimistic Most likely Pessimistic A B C D E F G H A B C D,E F,G Required (a) Draw the PERT network and find out the expected project completion time. (b) What duration will have 95% confidence for project completion? (c) If the average duration for activity F increases to 14 days, what will be its effect on the expected project completion time which will have 95% confidence? For standard normal Z= , area under the standard normal curve from 0 to Z= 0.45) (d) What will be the probability of the project completion on or before 27 days? Lecturer, DBA, IIUC, website: 10