How Can Heavy Civil Projects Take Advantage of 4D Construction?

Engineers, construction managers, and contractors are leveraging 4D construction modeling to help keep projects profitable and on schedule, but adoption for civil construction is lagging behind building and plant.

As 3D building information modeling (BIM) continues to be the preferred technology-enabled process for design delivery, construction firms have looked for ways to leverage these 3D BIM models for downstream construction workflows. Now, engineers are incorporating 4D modeling into their workflows. The concept adds a time dimension to 3D CAD models that enables teams to analyze the sequence of events on a timeline and visualize the completion of construction tasks. This concept can be extended to “nD,” where additional dimensions represent other types of information added to the 3D model context.

Engineers, construction managers, and contractors are leveraging 4D construction modeling to drive significant value in workflows that once involved a great deal of risk and many inefficiencies during the construction phase of a project. Some examples include:

• Model-based scheduling and simulation. It is far more efficient to build virtually first than to find mistakes in the field. A 4D model allows planners and construction staff to visualize the construction sequencing, including staging (for example, cranes, material storage, and site access). The 4D model helps identify errors in the plan and optimize the path of construction. It is also a better way of communicating the plan to the entire construction team.
   
• Model-based quantity take-offs (QTO) and estimating. A model-based approach in which means, methods, quantity calculations, and cost codes are linked to model objects, enabling more accurate estimates, rapid iteration if designs change, and the incorporation of cost in the project plan optimization. With this information, organizations can put together more accurate tenders.
   
• AR/VR and model-based field inspection and progress tracking. A geo-referenced construction model can be brought into the field, with field staff using web and mobile apps to provide data access and capture in the field with the 3D model as context. The process ensures that field staff, for example, are collecting data about the correct constructed asset because they use its model object (virtual representation) as a reference for the task they are completing.

The bottom line is this: Developing a construction model from the design BIM model to drive 4D workflows results in projects that are more likely to be on time and profitable.

The Current Situation within Heavy Civil Projects

So, if 4D construction modeling is this useful, why is it not used on every project, and why do we see only very little adoption on civil (horizontal) construction projects? It is often easier for construction teams to leverage model-based workflows when they have the design model. This is not always the case, and specifically for civil projects this happens less often (than on building or industrial plant projects), because infrastructure owners (for example, departments of transportation) do not specify 3D models as the design deliverable to contractors. That is changing, however, as countries like the UK drive BIM specification and as design/build delivery models gain acceptance.

Also, unlike building or plant BIM models, civil design models are not very usable for 4D. And, that has been the case since the first 4D software tools became available in the last decade. Building and plant models are delivered with a high degree of componentization and related engineering information. For example, a building model includes objects such as doors, windows, walls, lights, pipes, and so on, that are very discrete and can be directly connected to a construction schedule.

Civil models are not componentized in this way, and therefore require secondary processing steps to turn model objects into constructible components. For example, a 25-mile civil roadway/corridor model is often one long object, unless split by a bridge or interchange. This type of model object is not a constructible component since it does not represent how that 25 miles of road surface, aggregate, barrier wall, and curbing will be constructed. As a result, it cannot be directly connected to time or cost, which has been a dilemma for the past decade and has required construction firms to rebuild the models into many model objects within the design authoring tools. This presents an obstacle to adoption, since it requires a high degree of knowledge of complex design modeling solutions.

A Solution that Enables 4D Civil Construction

Many civil construction firms have had to take matters into their own hands, employing virtual design and construction (VDC) engineers that were proficient in civil design modeling software or attempting to develop their own in-house solutions. Bentley Systems, a developer of civil design and engineering software applications, seeks to change that. Bentley has horizontally expanded SYNCHRO Pro, its 4D modeling solution, to now address civil projects.

Specifically, Bentley’s SYNCHRO 4D offering has expanded its new SYNCHRO construction portfolio to address the above issues. SYNCHRO 4D includes a modeling environment purpose-built for construction firms that enables them to:

• Navigate any model (civil, industrial, or building) easily, including aggregate models.
   
• Split model objects, including civil models, into constructible components. This includes splitting of meshes and solid model objects along alignments, object edges, and within polygons. The process allows engineers to easily create models that are constructible based on project phasing (construction work areas) or means and methods (work packages).
  
  
  Break down big projects into smaller pieces — constructible components for estimating and planning.
   
• Apply construction data to the new model objects, which retain their relationship to the original parent model object. This data includes work breakdowns, schedules, resources, cost codes, and quantity calculations. The result is a construction model that enables downstream workflows such as model-based QTO, 4D scheduling and simulations, production work planning, and progress tracking in the field.
  
  
  Assign cost codes and work breakdown structure including quantities, resources, and structured data.

Now, all project types and all model object classes can be part of 4D construction modeling workflows. And, it’s about time this became easier for heavy civil construction professionals.