Civil engineers who are regularly engaged with architects or structural engineers may already be familiar with BIM, but for those who are involved in designing roads and highways, the process is a whole new world, but one that is highly relevant now and will continue to grow in importance.
BIM helps not just in constructing ‘buildings’ but also in building any sort of infrastructure. It is an integrated process built on coordinated and reliable information about a project from design through construction and operations.
BIM can be considered a thought process that governs work through various stages of the project in the shape of information that stays digital, consistent and coordinated. Hence, the chief benefits of BIM are that there is no duplication of information. It is a constantly updated centralised database model and streamlined flow of information from field (survey) to design and finally to construction and maintenance/operations.
BIM and civil engineers
Implementing a BIM process for road and highway design starts with the creation of coordinated, reliable design information about the project, resulting in an intelligent 3-D model of the roadway. The elements of the design are related to each other dynamically, not just points, surfaces, and alignments, but a rich set of information and the attributes associated with it.
For example, halfway through a roadway design project the profile may need adjustments to a vertical curve and the grades. By adjusting the profile, all of the related design elements update automatically, allowing the designer to instantly see the impact.
In this way, BIM facilitates evaluation of many more design alternatives. As part of the design process, civil engineers can leverage the information model to conduct simulation and analysis to optimise the design for constructability, sustainability and road safety. Finally, with a BIM process, design deliverables can be created directly from the information model. Deliverables include not only 2D construction documentation, but also the model itself and all the rich information it contains, which can be leveraged for quantity take-off, construction sequencing, construction stake-out, as-built comparisons and even operations and maintenance.
In the case of construction stake-out, digital points are added in the office to the information model and can be sent directly to total station equipment on site. This equipment has the ability, once coordinated to stake-out numerous points robotically removing the need to generate stake-out points from 2D CAD or paper drawings. This process allows a more efficient and accurate way to link the office to the site and through verification of the as-constructed, links the site back to the office.
The use of modelling, 3-D visualisation and analysis is nothing new for road and highway design professionals, but with traditional drafting-centric approaches, design, analysis and documentation become disconnected processes, making evaluation of what-if scenarios inefficient and cost prohibitive.
By dynamically connecting design, analysis, and documentation in a BIM workflow, most of the effort in a roadway design project is shifted back into the detailed design phase when the ability to impact project performance is high and the cost of making design changes is low. This allows engineers to spend more time evaluating what-if scenarios to optimise the design and less time generating construction documentation.
Machine guidance applications can benefit significantly from a BIM model, an object based model supports attribute meta data associated to work packages for specific machine types. High accuracy paving machines require parametric models, while earthmoving machinery can work will with surfaces, string-lines as well as parametric models.
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