Midterm - Construction Planning and Scheduling PDF

MIDTERM INTRODUCTION To Quantity take-off, Estimating, and Quantity Surveying INTRODUCTION Quantity Take-off, Estimating, and Quantity Surveying are three interrelated processes that form the backbone of the construction industry. They play a crucial role in ensuring the successful planning, execu...

MIDTERM INTRODUCTION To Quantity take-off, Estimating, and Quantity Surveying INTRODUCTION Quantity Take-off, Estimating, and Quantity Surveying are three interrelated processes that form the backbone of the construction industry. They play a crucial role in ensuring the successful planning, execution, and completion of any construction project. QUANTITY TAKE-OFF It is the process of extracting quantities from drawings and specifications. It involves using measurement techniques to determine the dimensions of various elements and calculating their corresponding quantities. Accurate quantity take-off is essential for: Estimating: Providing the data needed for estimating the project costs. Quantity surveying: Creating a detailed bill of quantities. Material procurement: Ensuring that the correct quantities of materials are ordered. 4 COST ESTIMATING Involves predicting the total cost of a project. This includes direct costs like materials, labor, and equipment, as well as indirect costs such as overhead, profit, and contingency. Accurate estimating is essential for: Financial planning: Determining the budget for the project and securing necessary funding. Bid preparation: Submitting competitive bids for tenders and contracts. Risk management: Identifying potential cost overruns and developing strategies to mitigate them. 5 QUANTITY SURVEYING It is the process of measuring the quantities of materials, labor, and equipment required for a construction project. It involves using standardized measurement techniques and conventions to create a detailed bill of quantities. Accurate quantity surveying is crucial for: Material procurement: Ensuring that the right number of materials is purchased to avoid shortages or excess stock. Cost control: Tracking the actual costs incurred against the estimated quantities to identify potential cost deviations. Contract administration: Managing variations and claims arising from changes in the project scope. 6 SUMMARY OF COMPARISON: Feature Quantity Take-off Cost Estimating Quantity Surveying Extracting quantities Predicting project Purpose Measuring quantities from drawings costs Detailed Scope Overall project Specific quantities measurements Bill of quantities, Output Bill of materials Cost estimate Detailed unit price analysis 7 A well-prepared estimate and bill of quantities provide valuable insights into the scope of work, resource requirements, and potential constraints. This information can be used to create a realistic project schedule that allocates appropriate time and resources to each task. By understanding the estimated costs and quantities, project managers can identify critical path activities and prioritize tasks accordingly. This helps in ensuring that the project is completed on time and within budget. CONSTRUCTION PLANNING AND SCHEDULING INTRODUCTION One of the most important responsibilities of construction project management is the planning and scheduling of construction projects. For many years, efforts have been made to plan, direct, and control the numerous project activities to obtain optimum project performance. Because every construction project is a unique undertaking, project managers must plan and schedule their work utilizing their experience with similar projects and applying their judgment to the particular conditions of the current project. CONSTRUCTION PLANNING Construction planning encompasses the initial phase of project management, where project objectives, requirements, and constraints are defined. Key considerations in construction planning include site analysis, risk assessment, and the development of strategies to address potential challenges. CONSTRUCTION SCHEDULING A construction project schedule involves the creation of a detailed timeline that identifies when specific tasks and activities will be executed throughout the project lifecycle. 11 Planning is the “what” you will do, Scheduling is the “how” and “when” you will do everything included in your plan. 12  USING PROJECT PLANNING AND SCHEDULING DURING ALL FIVE PHASES OF CONSTRUCTION: Construction Phase Plan Project Area 1. Concept and Initiation — This is where you evaluate the overall project and identify Planning and define objectives, feasibility, and if it’s the right fit for your business. 2. Planning — Here, you get into deeper details about how you’ll get a job done. This covers everything from creating the full scope of work and budget to crew planning and Planning gathering all the information you’ll need to build a schedule. 3. Execution — This is when you get to work. The schedule is the master document to Scheduling stay on track and communicate regularly with your crews and subcontractors. 4. Performance and Monitoring — All ongoing work needs to be monitored and reviewed to ensure things are getting done as planned. Your schedule gives you a Scheduling framework to review past activities and adjust for the future. 5. Project Close — Once all aspects are delivered and signed off, the closeout tasks in Scheduling your schedule will ensure your client is happy and ready for a smooth handoff. 13 SCHEDULING INVOLVE FOUR MAIN STEPS: 1. Performing breakdown of work items involved in the project into activities. 2. Activities representation/relationships 3. Identifying the proper sequence by which the activities should be executed. 4. Estimating and assigning the resources, time and cost of individual activities. 14 1. WORK BREAKDOWN STRUCTURE A WBS is a deliverable-oriented grouping of project components that organizes and defines the total scope of the project. Any work not in the WBS is outside the scope of the project. It is used to develop or confirm a common understanding of project scope. Each descending level within the WBS shows an increasingly detailed description of the project deliverables. ❑ Task level: A task is an identifiable and deliverable major work which can be performed without major interference from other tasks. ❑ Work package level: A work package contains an identifiable, constable and controllable package of work. ❑ Activity level: An activity is a subdivision of a work package and is defined as a work which has a definite start and end and consumes resources and time, and which is measurable. 15 16 2. ACTIVITIES RELATIONSHIP Relationships are defined from the predecessor to the successor activity. Four types of dependency relationships exist: A. Finish to start (FS): The successor activity can begin only when the current activity completes B. Finish to finish (FF): The finish of the successor activity depends on the finish of the current activity. C. Start to Start (SS): The start of the successor activity depends on the start of the current activity. D. Start to Finish (SF): The successor activity cannot finish until the current activity starts. 17 18 3. SCHEDULING TECHNIQUES USED IN CONSTRUCTION MANAGEMENT: A. Gantt Chart B. Network Analysis a) Project Evaluation and Review Technique (PERT) b) Critical Path Method (CPM) 19 SCHEDULING TECHNIQUES USED IN CONSTRUCTION MANAGEMENT: A. Gantt Chart A project management tool that illustrates work completed over a period of time in relation to the time planned for the work. It typically includes two sections: the left side outlines a list of tasks, while the right side has a timeline with schedule bars that visualize work. Advantages: A simple format and readily understood at all levels of management It can provide a quick, visual overview of a project in convenient way to monitor job progresses, schedule equipment and crews. 20 SCHEDULING TECHNIQUES USED IN CONSTRUCTION MANAGEMENT: A. Gantt Chart Disadvantages: Interdependencies among activities are difficult to show. The bar chart itself doesn’t provide a basis for ascertaining which activities are critical and which are floaters. It is not an adequate planning and scheduling tool because it doesn’t show a detailed, integrated and complete plan of operations. Can't tell what will be the effect of a delay today will have on the timing of future activities. 21 GANTT CHART How to create a GANTT chart GANTT charts incorporate four steps into the process: 1. List tasks: Use a work breakdown structure to identify all the tasks and subtasks needed to complete the work. 2. Arrange your timeline: Determine the start and end date for each task, and draw a horizontal bar on the right side of the chart to set the duration. 3. Set project milestones: Add key dates, deliverables, or deadlines to your Gantt chart as milestones. 4. Identify dependencies: Draw a dependency line between related tasks to link them to each other. 22 SAMPLE GANTT CHART: 23 SAMPLE PROBLEM: ACTIVITY DURATION (DAYS) PREDECESSOR Using the details A 3 None shown below, build B 3 A a Gantt-chart to find the project’s C 5 A total duration: D 4 B E 5 B F 3 C G 3 D H 3 F I 6 F J 2 G K 11 G L 2 K 24 SAMPLE PROBLEM: Project Total Duration: 26 Days 25  Abbreviation PERT CPM SCHEDULING Project Evaluation and Review Technique Critical Path Method TECHNIQUES USED What does It Mean? IN CONSTRUCTION MANAGEMENT: PERT is a popular project management technique that is applicable when the time CPM is a statistical algorithm which has a certain start and end time for a project B. Network Analysis required to finish a project is not certain Difference PERT vs CPM Developed to handle unpredictable activities, such as research Developed to handle predictable activities, such as construction. and development. Probabilistic, with activity durations Deterministic, assuming that activity estimated as optimistic, pessimistic, or durations are known and clearly defined likely Nodes used in the diagram are events, and The diagrams look similar, but the boxes, the arrows between them are the tasks. or nodes, are the tasks themselves. Focuses on the activity (milestones), and so Task focused, and so is better when is excellent when looking at the project considering the tasks from the point of from the point of view of the project view of the people completing them. 26 customer. TERMS When working with PERT/CPM charts, one should also be familiar with these related terms and concepts: ❑ Activity: A work item identified for the project being scheduled. ❑ Event: An event is used to signify the beginning or the end of an activity and can be shared by several activities. An event can occur only after all the activities that terminate at the event have been completed. ❑ Node: circles or rectangles representing project milestones and major events. ❑ Line/Arrow: Shows the required order of tasks in a project or process. 27 PERT VS CPM 28 PERT How to create a PERT chart PERT charts incorporate four steps into the process: 1. Define all tasks that must be completed. 2. Identify all dependencies between the tasks, that is, the order in which those tasks must be performed. 3. Draw the nodes that represent the events and milestones, and then draw the vectors that represent the tasks, using arrowed lines to show the sequence and dependencies. 4. Identify the completion time for each task. 29 PERT Basic patterns for arrow diagrams: 1. Basic Activity: Activity B cannot start until Activity A is completed. 2. Burst Activities: Activity B is immediately followed by Activities C and D, which may be performed concurrently. 30 PERT Basic patterns for arrow diagrams: 3. Merge Activities: Activity G cannot start until both activities E and F have been completed. 4. Cross Activities: Both activities H and I must be completed before activity J or K can start. 31 PERT Basic patterns for arrow diagrams: 5. Dummy Activity: Both Activities A and B must be completed before Activity C can start; however, the start of activity D depends upon the completion of activity B alone. The dash-line arrow is considered a DUMMY ACTIVITY, having no duration and used to show the restriction. 32 PERT Basic patterns for arrow diagrams: ADDITIONAL RULES: - The network must be continuous. - The Network must have definite No activity should be disconnected. (No dangling) points of beginning and finish. - There should not be a loop formation in a network, No activity should lead back to previous activity “No looping”. 33 PERT When determining completion time, there are three-time estimates considered: ▪ Optimistic time: Minimum time it takes to complete a task. ▪ Pessimistic time: Maximum time it takes to finish a task. ▪ Most likely time: Best guess of how long a task will likely take, assuming no problems arise. 𝑂 + 4𝐿 + 𝑀 𝐸𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑇𝑖𝑚𝑒 = 6 34 SAMPLE OF ESTIMATED TIME: The following table shows the tasks, dependencies, and estimated times for each task and the calculated Expected Times: TASK OPTIMISTIC MOST LIKELY PESSIMISTIC EXPECTED PREDECESSOR IDENTIFIER TIME (O) TIME (M) TIME (P) TIME (TE) A NONE 4 5 12 6 B A 2 3 4 3 C B 6 8 22 10 D C 4 6 8 6 E C 3 4 5 4 F E 2 4 6 4 G D,F 4 6 8 6 35 H C 5 7 15 8 SAMPLE PROBLEM: Develop a network diagram for the project specified below: 36 CPM How to create a CPM chart CPM charts incorporate four steps into the process: 1. Define activities and tasks and list them in sequential order. 2. Calculate the estimated time for completing each task on the list. 3. Define dependencies by deciding which tasks are related to others and which require other tasks to be finished before they can start. 4. Create a chart or map that shows the relationships between dependencies. Add the estimated time for each task in a dependency sequence. The sequence with the longest time frame is the critical path. 38 CPM Basic recommendations on drawing diagram: 1. The activities in the node diagrams are preferable to be drawn as rectangles instead of circles. 2. Don’t connect from top or bottom. Sides only. 3. Don’t combine relationship lines. 4. Design from left to right in chronological order 39 CPM Basic recommendations on drawing diagram: 5. Minimize line crossing. 40 SAMPLE OF SIMPLE CPM CHART: 41 42 CPM The critical path method consists of a series of calculations to determine the duration of tasks and the critical path. The primary metrics are: 1. Earliest start time (ES): The earliest possible date you can start an activity considering the dependencies 2. Earliest finish time (EF): The earliest possible date you can complete an activity considering its ES and duration 3. Latest start time (LS): The last possible date you can start an activity before causing a significant project delay 4. Latest finish time (LF): The latest possible date you can complete a task based on its LF and duration 5. Task duration (t): The total amount of time it takes to complete an activity 43 CPM The critical path formula has two parts: 1. Forward Pass: used to calculate the ES and EF. 2. Backward Pass: used to calculate the LS and LF. 44 CPM 1. Forward pass The ES of the first activity on any path will always be 1 since it indicates the start, i.e., the first day of your project. The ES of all other activities equals the earliest endpoint of the preceding activity plus 1: ES = EF of preceding activity + 1 The EF equals the sum of ES and the duration of the activity minus 1: EF = ES + t – 1 45 CPM 2. Backward pass The LF of the last activity on any path will always be the same, as it indicates the end, i.e., the last day of the project. The LS of an activity equals the difference between LF and the duration of the task plus 1: LS = LF – t + 1 The LF of an activity equals the LS of the succeeding activity minus 1: LF = LS of succeeding activity – 1 46 CPM OTHER TERMS IN CPM: Float/Slack: The float or slack represents how long a non-critical task can be delayed without affecting the entire project timeline. Critical tasks don’t allow delays, so their float score is automatically 0. There are two types of float: A. Total float: The amount of delay that doesn’t affect the project completion date (LS-ES OR LF-EF) B. Free float: The amount of delay that doesn’t affect the start date of the succeeding task (ES of succeeding activity – EF of current activity) 47 CPM OTHER TERMS IN CPM: Critical Path: It represents a series of activities for which each activity is a Critical activity (zero float time) Critical Path Drag: is the amount of time that an activity or constraint on the critical path is adding to the project duration. Critical Activity: any delay on the start or finish of a critical activity will result in a delay in the entire project. 48 SAMPLE PROBLEM: The following details are available regarding a project: TASK PREDECESSOR DURATION Determine the critical path, the IDENTIFIER critical activities and the project A NONE 10 completion time. B A 20 C B 5 D C 10 E A 15 F A 15 G C,F 5 H D,E,G 20 49