Construction Scheduling

CONSTRUCTION SCHEDULING

Construction scheduling can be defined as the process of listing all the activities to be carried out with the planned start and completion dates. It is an entire blueprint which shows how the project will be executed and the sequential relationship among the various activities or operations in a project so that work can be carried out in an orderly and effective manner. The schedule outlines project milestones and tracks project progress to keep everything on time and on budget. It's the backbone of a successful project management for construction. The steps involved in construction scheduling are:

❖ The project is divided into number of operations and the sequences of these operations can be derived after knowing their relationship properly.

❖ The quantity of work involved in each operation has to be calculated. besiver an

❖ The time required for completion of the project and different activities are to be calculated.

 

CLASSIFICATION OF SCHEDULING

In general, construction scheduling is classified based on two aspects:

Resource-oriented scheduling is one of the most thoughtful construction scheduling methods. As the name suggests, this scheduling technique focuses on identifying the resources available for the construction projects and utilizing them efficiently to avoid wastage while ensuring timely and effective completion. It also reviews the resources, the parties and activities that will need the resources, and the particular time at which it will be required to manage the process efficiently. In time oriented scheduling, the prominence is on determining the completion of the project with the given priority relationships among the activities. Most scheduling software is time-oriented, although practically all of the programs have the capability to introduce resource constraints. Scheduling can be further classified into different types according to the requirement for which it is done. The various types of construction schedules can be listed as follows:

❖ Construction Material Schedule

❖ Labor Schedule

❖ Equipment Schedule

❖ Financial Schedule

❖ Control Schedule

❖ Organization Schedule

❖ Summary Schedule

 

METHODS OF SCHEDULING

Construction scheduling can be done depending on the nature of the project. The various methods of scheduling are discussed as follows:

❖ Gantt chart

❖ Q Scheduling

❖ Last Planner System

❖ Line of Balance

❖ Work breakdown structure

❖ Critical Path Method (CPM)

❖ Program Evaluation and Review Technique (PERT)

Gantt chart:

Henry Gantt (1861-1919), an American mechanical engineer, designed the Gantt chart. Gantt chart is a common construction scheduling method which utilizes the bar charts to depict the plan and the progress of the project. The unique aspect of this scheduling technique is that it highlights the dependency of one task or activity on the other to be completed efficiently in the given time. These are also known as bar charts. A Gantt chart helps in scheduling, managing, and monitoring specific tasks and resources in a project. The chart shows the project timeline, which includes scheduled and completed work over a period. The Gantt chart aids project managers in communicating project status or plans and also helps ensure the project remains on track.

The above figure shows a bar chart which has 6 distinct activities A, B, C, D, E and F which are to be performed in 7 weeks. The chart can be explained as follows:

❖ Activity A is the first activity and it extends upto 2 weeks.

❖ Activity B and C can be started simultaneously, since they are independent of each other.

❖ Activity D can be started only after completion of activity A.

❖ Activity E starts when activity B is completed.

❖ Activity D and E completes in the same time.

❖ Activity F is the last activity and it starts after completion of D and E.

❖ Total duration of the project is 7 weeks.

*Q Scheduling: Quantitative scheduling, also known as Q scheduling, uses bar charts to visualize resource quantities and the locations in which the resources will be used. It is a different type of construction scheduling method. It focuses on scheduling the materials and equipment used in the project. It provides a clear description of the materials used and required in the project through a bar chart. This type of scheduling essentially provides support against delays due to improper material management. It is one of the least common scheduling methods in construction. It is only used when tasks are repeated, but variable quantities of resources are used.

❖ Last Planner System: The last planner system is a unique scheduling method that is more like a planner than a method or tool. The last planner system bridges the gap between the teams or workers. It also devised a construction project schedule to not miss out on the important details. It (atnavel smoothens the communication to follow the schedule efficiently and complete the project on time. It is also termed as Pull planning. This scheduling technique establishes vital project milestones, like the project completion date, then works backward to outline the steps to achieve each milestone quickly and efficiently. The defining features of pull planning are strong collaboration and the backward timeline.

❖ Line of Balance: Line of balance (LOB) is another common construction scheduling method. This scheduling method is usually implied in projects that include repetitive activity. The balance scheduling method measures the cost, time, and project completion plan and ensures nothing falls behind the schedule. These type of schedules are very uncommon but are sometimes used when a construction project consists of highly repeatable and similar tasks. These are most commonly used for roadways, pipes, and other horizontal construction projects. For repeated work activities, they allow for intensive cost and time optimization, and it is also much easier to change and update line of balance schedules. LOB is a management control process for collecting, measuring, and presenting facts relating to time, cost, and accomplishment. It shows the process, status, background, timing, and phasing of the project activities, thus providing management with measuring tools that help:

❖ Comparing actual progress with a clear objective plan.

❖ Examining only the deviations from established plans, and gauging their degree of severity with respect to the remainder of the project.

❖ Receiving timely information concerning trouble areas and indicating areas where appropriate corrective action is required. is opsig anbla

❖ Forecasting future performance.

Scheduling with LOB

For preparing a line of balance schedule, the following procedures should be adopted:

❖ Prepare a logic diagram.

❖ Estimate the man-hours required to complete each operation.

❖ Choose buffer times which will guard against the risk of interface between operations.

❖ Calculate the required output target in order to meet a given project completion date.

❖ Complete the LOB schedule.

❖ Examine the schedule and assess possible alternatives to bring about a more 'balanced' schedule.

Advantages of Line of Balance (LOB)

The benefits of using the LOB technique are

❖ A better understanding of the amount of work taking place at a certain time in a specific place.

❖ Optimized resources for a large number of repeated work activities.

❖ Allows easier cost and time optimization analysis.

❖ Easy to modify, update and change the schedule.

❖ Better management of subcontractors and resources.

❖ Identifies issues in advance.

Work breakdown structure:

The Work breakdown structure (WBS) is the tool that is used to record and communicate the project deliverables and sub-deliverables as well as the accomplishments and sub-accomplishments. In any construction project, the various activities that make up the project have to be clearly identified. The process of breaking the project into easily identifiable major systems, their sub systems and discrete activities is called the work breakdown structure. WBS is a visual, hierarchical and deliverable-oriented deconstruction of a project. It is a helpful diagram for project managers because it allows them to break down their project scope and visualize all the tasks required to complete their projects. All the steps of project work are outlined in the work breakdown structure chart, which makes it an essential project planning tool. The final project deliverable, as well as the tasks and work packages associated with it rest on top of the WBS diagram, and the WBS levels below subdivide the project scope to indicate the tasks, deliverables and work packages that are needed to complete the project from start to finish.

Types of WBS

Based on whether we want to divide the project in terms of time or scope, there are two main types of WBS:

(i) Deliverable-based WBS: A deliverable-based WBS initially breaks down the project into all the major areas of the project scope as control accounts, and then divides those into project deliverables and work packages. Many construction specialists favor a deliverable-oriented (or product-oriented) WBS, which revolves around tangible deliverables, not processes. In construction, the elements of a deliverable-oriented WBS are physical components of the building or interim deliverables that you need in order to produce pieces of the building. Interim deliverables can include plans and specifications. The components of a deliverable-oriented WBS are nouns rather than verbs, because this particular structure focuses on the physical products of a project rather than on processes.

The advantages of a deliverable-oriented WBS:

❖ It simplifies the process of cost estimating.

❖ It allows us to see the total work scope.

❖ It clarifies the relationships among elements.

❖ It can be used during all project phases.

❖ It's easier to modify as the project changes.

❖ It supports earned value management.

(ii) Phase-Based WBS: Alternatively, a phase-based WBS divides construction into steps or stages. This kind of WBS focuses on the processes you require to achieve the deliverables. Verbs rather than nouns appear in this type of WBS. This kind of document is also known as a process-oriented, task-oriented, or activity-oriented work breakdown structure. A construction manager divides the project into its component gojni i activities. In the graphical representation of a phase-based WBS, these qactivities often proceed in chronological order. The phase-based WBS ΤΟΥ 101 2sharose in part to ease the transition from a deliverable WBS to a project schedule. Planners translate the deliverables into activities and milestones, then create a project schedule network diagram. This diagram, which consists of boxes and corresponding arrows indicating the flow of work, is the basis of the project schedule.

Types of WBS Schedule

The various types of work breakdown structure schedule charts are discussed below:

❖ Work Breakdown Structure List: It is also termed as an outline view. This is a list of work packages, tasks and deliverables. It's probably the simplest method to make a WBS, as per the requirements.

❖ Work Breakdown Structure Tree Diagram: This is the most commonly seen type of WBS. The tree structure illustration of a WBS is an organizational chart that has all the same WBS elements of the list such as phases, deliverables, tasks and work packages. It represents the workflow or progress as defined by a diagrammatic representation.

❖ Work Breakdown Structure Gantt chart: A Gantt chart is both a spreadsheet and a timeline. The Gantt chart is a WBS that can do more than a static task list or tree diagram. The Gantt chart helps to link the dependencies and set milestones or a baseline. This is the most common version in project management software.

Steps to Create a Work Breakdown Schedule

To create a WBS for a construction project, there are six simple steps to be followed:

❖ Define the Project Scope, Goals and Objectives - Project goals and objectives set the rules for defining the project scope. Project scope, team members, goals and objectives should be documented in the project charter.

❖ Identify Project Phases & Control Accounts - The next level down is the project phases: larger project activity statements are split into a series of phases that will take it from conception to completion. Control accounts can also be created, which are task categories for different work areas which can be tracked.

❖ List the Project Deliverables - Project deliverables should be listed and the work needed for those project deliverables are also noted (sub-deliverables, work packages, resources, participants, etc.).

❖ Set WBS Levels - The WBS levels make the work breakdown structure as a "hierarchical deconstruction of the project scope”. The final project deliverables are to be started and all the deliverables and work packages needed to get there from the start.

❖ Create Work Packages - The deliverables are split down into every single task and subtask that is necessary to deliver them. These are then grouped into work packages.

❖ Choose Task Owners - With the tasks now laid out, it can be assigned to the project team. Each team member will be provided with the work management tools, resources and authority they need to get the job done.

❖ Critical Path Method: The critical path method is one of the most common construction scheduling methods, and it is also called a critical path analysis. This type of schedule is developed by creating a network diagram highlighting the sequence of tasks and projects following the specific path. The CPM creates a schedule based on critical activities, which must be completed before another activity can begin. Once critical activities are identified, they are scheduled in sequence to determine the least amount of time a construction project can be completed.

❖ Program Evaluation and Review Technique (PERT): The program evaluation and review technique is one of the most critical construction scheduling methods. This is because it pays more attention to analyze all the individual project activities. In other words, PERT evaluates and reviews the project's activities in progress and evaluates the time duration in which they will be completed.

 

USES OF CONSTRUCTION SCHEDULING

The main uses of construction scheduling can be listed as follows:

❖ Construction scheduling gives information regarding the quantity of work, labour, machinery, equipment etc required for a particular period.

❖ The progress of the work and the expenditure can be checked and duly adjusted.

❖ The project can be completed systematically and effectively.

 

 ADVANTAGES OF CONSTRUCTION SCHEDULING

The major benefits of construction scheduling are as follows:

❖ The resources required at various phases of work execution can be listed and duly procured thereby preventing the shortage and overbuying of resources.

❖ The alternative methods of work execution can be evaluated and the most feasible alternative can be selected.

❖ The work progress can be well monitored and evaluated.

❖ Construction scheduling delivers the starting and completion dates of each activity and thus optimization of resources can be managed.

❖ It prevents undue delay and extension of time.

❖ It helps to complete the entire project within the planned approved budget preventing cost overrun.