4D Scheduling; The Future of Planning? The purpose of this paper is to provide the reader with an understanding of the concept of 4D Scheduling, how and where it is used, whether it is currently of benefit to the construction industry and can it revolutionise planning in a positive manner for small, medium and large scale construction Projects. What is it? 4D Scheduling is a Programme which allows the Project Plan to interface with 3D software and build a live model which displays the Project Progress in real time.
The 4D planning tool is used at Tender and Preconstruction stages, kept live throughout the project and reviewed upon completion to assess Project Success. To understand how the Programme interfaces and accurately reflects progress we first need to define and understand Building Information Modelling. Building Information Modelling is a building design and documentation system based on coordinated, reliable, high quality information.
This system enables the design and construction teams to create and manage information about a project consistently and reliably across the scope of the project. This information is stored in a unique model which ensures the information is coordinated, consistent and complete. Traditionally Building Projects were illustrated with manually created drawings, information was added to these illustrations by using motes and specifications. As CAD technology progressed this system became automated, though the output remained the same.
The visibility which the BIM provides to all Project Team members contributes to the overall success of the Project through better coordination, improved accuracy and an ability to make informed decisions earlier in the Project. 4D BIM uses 3D CAD or 3D modelling and links individual 3D parts or assemblies with the project delivery timeline to add time; the fourth dimension, to the BIM. This management technique vastly improves the project management and delivery of construction project of any size or complexity. 4D Scheduling/Modelling
A 4D model incorporates a 3D/BIM with a Project Schedule so that all Stakeholders can visualise the sequence of Construction. The model may be created to varying levels of detail, from high level zone analysis during the design phase( this can be useful for allowing foremen, area owners and Health and Safety agree on areas of responsibility and ownership), to detailed breakdowns for use by subcontractors so they can coordinate their own activities during construction of a project. This same model can be updated and maintained through the duration of the project based on an updated schedule and 3D model.
The 4D elements are created by linking pre made 3D components to an activity in the Project Schedule. For example Task 1 is to erect 400m of Perimeter fencing. For every 10% which is completed on the Project Schedule, 40m of fencing will appear on the graphic. One aspect of 4D scheduling which is of particular aid to Planners is that it allows them to visualise a related sequence of activities in the construction process which may not have always instantly have occurred to them, such as changing location of traffic lanes and set down areas as buildings appear on a large site, or the changing locations/restrictions of swing space for cranes.
Like an actual event or construction stage these non visual type activities require both start and end dates in the schedule linked to 3D components so that they can be visualised in the model. 4D Scheduling in the Project Life Cycle; Though one of the most attractive uses of 4D (which I will detail later in this report) is at the bidding stage, there are three main stages of utilisation for the 4D model, Design, Tender and Construction. Design; 4D models can be used to determine , different configurations to Lay Down areas, Compound ownership, and Swing space for cranes to optimise the Project Layout and Project Schedule.
The model will allow for multiple alternatives which can be assessed in detail at relatively low cost. It can also allow the designer to provide alternatives to the original brief which can show how to crash the project schedule, and the effect can be shown visually with workflows , or the impact of external traffic to the site during peak hours can be assessed. Tender/Bidding; The 4D model is fully utilised at this stage to demonstrate the Contractors ability to understand, direct and execute the brief and instil confidence in the client that the Project will be delivered on.
The fact that time is linked to the 3D model allows the client to see the growth of the project and how all external factors have been taken into account and considered. It also generates a wow factor and allows the Contractor to stop and breakdown in detail different tasks at any stage of the presentation. Construction; 4D models can be used for several aspects of Construction, its Coordination and regular milestone reviews. From identifying and communicating where, how and when different trades will operate, to understanding the traffic, site and workflow processes.
The model can be used on site for progress reviews and compared to as built/scheduled plans, by the management for both milestone reviews, and indeed for claims purposes also. The overall model & Schedule can be broken down into individual components for communication between main and subcontractors, and also used for communication between subcontractors themselves. Where possible the Main Contractor will allow the subcontractor access to the schedule so that they can visualise, communicate and update as required. Another valid use of the model during the construction phase. Project Team & Implementation D modelling/Scheduling is a combination of both the design and the schedule, so it is crucial to have various members of teh Project team on board to design, schedule implement and maintain the process. The first step is deciding who will create the model and who will provide teh inputs. Typicially teh team can be broken down and defined as follows; 3D Modeller; Generates teh 3D model and updates as per design requirements. Scheduler; Generates the project schedule, timeline and provides updates. 4D Modeller; Links the 4D model, provides guidance to both the Scheduler and 3D Modeller for updates.
Project Stakeholders; Provide inputs on their own requirements and constraints at different stages of the project. Project Manager; Though the Project manager does not require direct operational input or control of the 4D Model, they need to consider and understand a number of crucial factors; Software Integration; Some 4D Software may only support certain formats of schedules and models. The project team should be confident that the 3D model and the supporting schedule are compatible and can be imported to the relevant 4D software.
Interface Issues; It is not a necessity for all stakeholders to create and edit the 4D model but it is beneficial for all stakeholders to view teh progressing model. Stakeholders may be allowed to view only teh required aspects of teh model which affects their work. This can be done by creating basic video files or animations that can be viewed by basic media players. Thus reducing teh outlay for smaller subcontractors on expensive software packages or licences where they may not be entirely required.