Throughout the evolution of the construction industry, both owners and builders have been looking for an ideal planning methodology, which allows them to effectively control the entire development of their projects and, thus, lead them to success. This ideal solution will not be presented, but, on the other hand, a more effective alternative, while adding a new variable – location.
“It is one thing to know about the location-based theory and its associated methods, it is another to know how to use that knowledge to build effective schedules for a project and to both plan for production efficiency and provide confidence.” – Kenley and Seppänen
As advocated by Kenley and Seppänen in the book “Location-based Management for Construction”, there is a difference between knowing location-based planning methods and knowing how to use them properly, achieving perfect planning, while at the same time controlling the production of the entire project. Companies in the sector continue to rely on CPM (Critical Path Methods) methods, generally via Gantt charts, despite being aware of their strong limitations.
Gantt charts were developed solely for planning workload, deadlines and responsibilities in a generalized way, and are perfectly suited for these roles. The problem is that these diagrams describe the process in a single location. That is, this method was not designed to plan and monitor multiple teams in different workplaces, although that is the purpose for which it is mostly used. In this context, the Line of Balance (LOB) appears as a solution to the main limitations of the traditional method, thus presenting new features: multiple locations, representation of the continuity of tasks, visualization of dependencies, resource movements and team planning, as well as the respective productivity. The main variables of this methodology are indicated in the following diagram.
DURATION + QUANTITY + LOCATION
Main variables of LOB theory.
Concept
In general, the Line of Balance can be defined as a graphical planning methodology that represents, in a single view, all the activities and locations of a work. Next, a figure showing the graphical representation of this method is presented. The vertical axis represents the project locations, the time on the horizontal axis and the lines represent the activities. The slope of the lines reveals the productivity of the activities, and the greater the slope, the greater the yield.
As an example, consider the three tasks represented below, in a typical Gantt chart, referring to a generic job.
This planning methodology, due to the ease of visualization and analysis of the work, drives an optimization in project management by resorting to changing the productivity of activities, continuity of work and better use of work locations throughout construction.
These changes may imply a variation in the productivity of the team(s) and/or a change in the composition and/or number of the work team(s). In the image below, the tasks were converted to the Line of Balance representation and optimized, proving the result of applying the assumptions of this method (continuity and similar production pace), obtaining a reduction in the total duration of the work without increasing the risk.
As can be concluded, this change in production implies a change in costs, resulting from the variation in the number of resources and their time allocation. In this context, it is important to highlight the fact that the balance sheet platform makes it possible to clearly manage all these resources and their respective changes. In short, the balance line allows you to compress the duration of the project, analyzing in the same view all activities and dependencies and gaps between them.
Software
Currently, this methodology is already integrated into BIM construction management software that considers both quantities and costs, which are linked to the locations where the modeled elements are located.
This article will focus on the potential of the software that is, from the point of view of ndBIM, not only the most complete but also easy to use: Vico Software's Schedule Planner. As this software is one of the constituent modules of Vico Office, it allows users to integrate the quantities, taken from the BIM model, with the respective resources and different locations, allowing the elaboration of highly detailed and optimized planning.
4D Planning results from the symbiosis between the 3D geometry of the BIM model and the optimization of the resources associated with it, the quantities being extracted from the geometry, allocated in the different areas of the project. From this point on, in the LOB view – Vico Flowline view –, it becomes feasible to change the sequence of tasks and locations, as well as the composition and size of the teams, the productivity and respective costs, the division of tasks (Split) and the introduction of slack (Buffers). By creating this optimized planning, it is possible to minimize – or even eliminate – interruptions and restarts, reducing the inherent risk and still preserving the continuity of the work.
The integration of the model, quantities, locations and budget is fundamental, taking into account the growing demand from building owners regarding planning that considers both the variation in costs and resources, throughout the different phases of a work. Thus, this methodology allows teams to plan the cost at a given point in the project and compare it with the current cost of the part of the work that has already been completed.
In order to achieve the true BIM 4D, the Schedule Planner not only allows the initial planning of the work in an efficient way, but also presents excellent tools for controlling the production of the work. It is possible to change to the control mode and, through the Schedule Task Control Chart view, enter the deadlines and amounts/percentages, effectively executed, in each location, for each activity.
This information is exposed in a control matrix where it is possible to visualize the tasks on the horizontal axis, the locations on the vertical axis and in each cell the planned start and end dates and the actual start and end dates or percentage executed. This information is transposed into a color code for easier visualization and analysis (explanation of colors in the image caption).
In this way, a representation of three scenarios is obtained: the planned, the real and the foreseen. The forecast is calculated based on the information entered on the work performed (quantities and time), which gives rise to real productivity applied to the work still to be done, in addition to taking into account existing dependencies. The tool also generates alarms and warnings for critical areas of the work, allowing the user to more closely control the tasks that could delay the total duration of the project.
The use of real productivities throughout the work to calculate the forecast is a big difference compared to Gantt tools, such as, for example, MS Project, which do not consider this data. In this way, the balance line allows for a better forecast of the end date of the project as well as the execution over time of all quantities of activities.
Vico Office also features a feature capable of creating a 4D simulation of the project, where it is possible to view, on video, the entire construction process of the work and the respective timetable due to the full integration of the model with the planning tool.
The 4D simulation is one of the automatic deliverables of projects planned with Vico Office. The 3D components of the model are directly linked to the budget, which in turn is associated with tasks with location information, worked on in the planning tool. In this way, the different tasks are grouped into 4D Groups that allow changing the behavior of the elements for visualization in the 4D simulation. This structure is represented in the diagram below:
The video results from the geometry of the model, the quantities per location and the productivity of the teams, introduced in the Schedule Planner, with the video speed adjusted by the user. This tool is extremely useful, as it acts as a facilitator and communication element with the owner, subcontractors and other stakeholders in the construction process, enabling a better perception of the work program. Likewise, it is also an important tool for quality control of the planning created on the balance line, allowing the user to verify, in 3D, if the order of execution of the works by location is feasible.
Last but not least, the Schedule Planner generates a vast array of graphs and reports, with all the forecast information, actual and planned, in terms of dates, productivity and resources, which can be easily interpreted by all those involved in the work or exported to Excel for data editing. You can see an example in the following image.
At the same time, resource histograms can be created (as shown in the following figure), by task or by resource, work cash-flow graphs, reports of existing time margins, quantities per location, work progress, tasks, etc.
Benefits
By implementing a project management system based on LOB theory, you can achieve a series of significant advantages, as seen below:
- Reduction of 10% in the total duration of the work: decrease achieved by the optimization that the LOB functionalities make possible;
- Planning optimization: allows you to manage durations, risk, continuity, predict cost peaks and reduce conflicts between critical activities;
- Ease of use: being an easy-to-use methodology, it makes the process faster;
- Value creation: less time spent on creation and more time for communication, creation of databases with task history, productivity and resources, among other tasks;
- Improved project control: software functionalities lead to more effective monitoring and control, which may imply an additional reduction of 10% in the total duration of the work;
- Greater continuity of work: by minimizing interruptions and keeping teams working longer, productivity can increase by up to 20%;
- risk reduction: this decrease is guaranteed by the more predictability of the method, achieved by planned margins, start dates of subcontractors' work, milestones, among others;
- Ease of creating simulations, changing tasks and dependencies: by allowing the simulation of different alternatives, it increases the rigor of the chosen solution.
- Durations oriented by actual quantities and productivities: Task duration is calculated scientifically and automatically.
Percentages taken from the book “Location-Based Management for Construction” (Kenley, R.: Seppännen, O., 2010)
Process
The LOB methodology, integrated into a BIM process, contrary to what professionals in the sector might initially think, is, after a first contact, simple to understand and analyze, resulting in a logical work development, accompanying the natural course of the preparation of the work.
The process begins, as a rule, with the preparation of the BIM model in order to automatically obtain quantities by location for the Schedule Planner. After the model, the sequence of procedures for preparing the planning should follow, in general terms, the structure presented in the following scheme:
Implementation
The implementation of a new methodology always faces some obstacles, highlighting people's natural reluctance to change and lack of familiarity with the process and tool. The adoption of the Line of Balance implies a paradigm shift in planning. The processes followed religiously for generations are outdated and, in the opinion of ndBIM, should be enhanced by a new methodology and, consequently, by new technologies.
A construction project involves multiple players in different phases who need to work as a team to lead the work to its success. The methodologies and tools in use in a company must be accepted and understood by everyone, under penalty of inefficiency and loss of information, and cannot be imposed on everyone as a software purchase package. The strategy must go through a prior diagnosis of the company, knowing the teams, their skills, experience and profile as well as the current processes in use by all. With this data it is possible to start implementing a new planning methodology, as well as any upstream processes for effective use.
There is no generic implementation solution applicable to any case. Processes and technology can be purchased and/or developed. However, without People's motivation and understanding this will not be effective.
Conclusion
Although there is still a predominant use of CPM diagrams associated with constructive planning, there is already some awareness of the intrinsic potential of the methodology presented here and, as such, its acceptance by companies should be growing, due to the success that some stakeholders have already proven.
Using the Line of Balance makes it possible to create a work program and optimize it without increasing risk by incorporating the locations, quantities, costs and productivity of the work. The control tools incorporated in the software that support it allow a superior forecast of the work to be carried out based on real productivity which, combined with the unit cost values, allows an excellent update to the financial schedule until the end of the work, in a simple and automatic way.
The Line of Balance is a solution for everyone who wants simple and quick planning, with a real optimization process, which really provides data for the construction management to make decisions. It allows the clear identification of conflicts and critical areas in the development of the work, as well as the management of gaps between tasks. It also presents all the information in compact views, contrary to the current industry standard of using Gantt charts, meaning that the work program can really become useful information for all stakeholders without much effort.
ndBIM can help you to implement this methodology in your company by providing a training program, in methodology and technology, in addition to providing adequate monitoring for success. Access the best implementation advice achieved by many 4D implementation cases! If you don't want to incorporate these skills, we can also provide you with 4D services, in a back office, like your partners!
