4D BIM for Construction


Posted by Jacqueline Chen on Oct 29, 2015 3:00:00 PM

Several months ago, I was involved in a complicated heavy highway project which included the reconstruction of multiple State roads, the preservation of several bridges, the replacement of partial MSE retaining walls underneath ramps, the replacement of two sign structures and upgrades to existing traffic signal systems, not to mention traffic switches, closures and detours of ramps, intersections, overpasses and pedestrian walkways. I recalled that my morning started with a review of drawings (296 pages, half-size) with a construction manager who had over 25 years of experience. We were requested to provide a draft of the design schedule along with a PS&E submission by end of the following week. Seven revisions were done after, and a “what if” analysis was performed to estimate open to traffic time of one major ramp and predict project finish dates with different notice-to-proceed dates.



Import your design and data digitally to create a 4D model

The other project I was recently involved with was to schedule the decommissioning and demolishing of a plastics plant. A high-level schedule was populated to cover all front-end design and decommissioning activities including materials purge, asbestos abatement, power lockout, water and steam shutoff, etc. The enormous project site was divided into 14 areas and the draft of the baseline schedule was over 32 half size pages in total. The Client also required monthly schedule updates of construction progress.

A similarity that I found between these two unrelated projects and all of the large scale projects with complex conditions that I worked on before was that they made life harder for schedulers and planners, and I hated to admit that I nearly felt lost after many revisions or updates of a zero-D Gantt chart. With that being said, unless schedulers have years of solid construction management knowledge and are talented with extraordinary spatial imagination capabilities (imagining sequence construction activities to show a 230 ton crane moving on a trestle and extended fingers to set 150’ long girders for a new bridge with over 10 spans adjacent to an existing bridge without having a crane staging plan), even after the design is done in 3D, schedules are still being created in a way in which they have no visual access to the entire project. What makes it worse, is that many schedulers are not involved in most of the communication and coordination of meetings, and not enough time is left for them to understand the project and finish the schedule - and yes, we are living in a world where everyone needs everything ASAP. When they rush their work, they are probably uncertain whether their schedule will work, even if they’ve gone through the logic step by step or had a senior coworker do a QA/QC review for them to make sure plans match design. Being able to foresee the construction and sequencing of all work seems to be a minimum requirement.

An ideal workflow to maximize the strength of your 3D models is to have them reorganized and provided in a logical construction sequence-(group 3D geometry by phase, level, etc., or even WBS) in addition to having them organized with traditional design disciplines or CAD levels. Meanwhile, schedulers and construction managers can participate in updating and optimizing the 4D model- sharing their insights, and driving the planning process. Later on, iteration demos and review meetings are conducted, questions can be answered and concerns resolved while participants are  able to see first, predict and adjust with full utilization and exchange of information. This is exactly how industry leaders are implementing and streamlining their 4D planning processes and fully utilizing their 3D design data.

As engineers, we give our utmost to get it done, get it done right and on time - this demands for our plan to be validated before construction. You are assured that your project will be delivered after you walk out of the project coordination meetings; nothing will keep you awake during night because you know exactly what will be delivered, installed and inspected for the next two weeks (when, where and how). What I am trying to say here is: be more proactive with your 3D model data, use it, re-organize it and move to the next stage, digitally so that you can gain the benefit of todays advanced digital efficiencies. Do NOT waste it.



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