Digital modelling today lies at the heart of construction disciplines, from the design phase to the operation of a building. Every day, engineers push the boundaries of its use to get to grips with and carry out tasks more efficiently than they did previously with more "traditional" means. But what about the construction phase? What would the digital model contribute to planning, for example? Egis, currently construction manager for the restructuring and extension of a historic building at the Pays de Morlaix hospital, in partnership with the architecture firm Lazo&Mure, wanted to test this innovation, which now bears a name: 4D scheduling. Here, we shed some light on this ingenious software solution that helps achieve better control over work planning and, moreover, improves communication with all stakeholders.
What’s 4D scheduling?
A 4D schedule associates the 3D digital model with the works schedule. This operation is carried out on 4D planning software (Navisworks, SynchroPro in our case, etc.), linking up a compilation of digital mock-ups in IFC format with a schedule drawn up on Microsoft Project or Primavera, for example. Once the data has been imported, the role of a "4D planner" is to assign the objects of the 3D model to the corresponding tasks on the schedule. Next, the planner works on the rendering: defining the appearance of the objects at the time of construction (these elements appear in green in the video), camera movement, definition of a time scale, etc. The rendering can take the form of a PDF (one view per month, for example) or an MP4 (video format).
4D: a new tool to meet the demands of increasingly restrictive projects
At a time when the proportion of refurbishment projects is increasing compared to new-build projects, and construction site environments are increasingly restricted, 4D planning provides a new response to these challenges.
The 4D planning approach is particularly well suited to projects with several phases, to those taking place on an occupied site (in order to manage all the flows) or to projects with an educational purpose or on which the project owner wishes to communicate.
In Morlaix, all contributors draw benefits from 4D
In Morlaix, the works planning for the new extensions is totally different from that of the heavy refurbishment work, in terms of both construction methodology and services. In addition, the extension and refurbishment works are carried out in parallel, which complicates the task of planning and the clarity of a Gantt chart, traditionally produced under Microsoft Project to visually represent the progress of the various activities (tasks) that make up a project.
This is what led Egis to produce and circulate a 4D schedule in the form of a 2-minute video in MP4 format to all the project's internal stakeholders (contractors, project owner, etc.) and external stakeholders (media, internal communication within the hospital) in order to improve understanding of the project schedule.
The video is a dynamic and entertaining way of representing a schedule for a project management office. Easier to understand than a Gantt chart with several hundred tasks, the video reassures the project owner and explains in a simple manner the sequencing and schedule designed by Egis. Also through the video, the project owner is also more comfortable communicating internally and externally on the key stages of the project up to handover.
The 4D schedule allows companies to view the entire project at a glance. It helps to anticipate the circumstances in which the work is performed (in particular how to access the work area at the start of a task) and the interactions between the different trades. The video encourages active and fruitful exchanges between contractors on the schedule during site meetings.
For Egis as a planner, better visual and spatial understanding of tasks makes for a better organised worksite and therefore reduces simultaneous jobs and optimises the work of contractors. With 4D planning software, it is easier to update the schedule and immediately visualise the reorganisation caused by a change. This supports the planner's work.
In a planning, scheduling and coordination assignment, the 4D schedule is the natural next step for a planner to incorporate the BIM approach.
On the principle of 4D planning, it is possible to add other "dimensions" to the digital model. These can be of any nature (production cost, energy consumption, carbon footprint, etc.). The use of the digital model for construction projects is clearly only in its early days!