Construction Managers Embrace 4D BIM for Safety
Read ENR/Tom Sawyer's article on 'how construction companies are using SMC in new ways to assess site safety.'Jobsite safety is an ongoing challenge. As preplanning gives way to activities and construction moves through its phases, the site, crews, equipment and logistics erupt into dynamic flow. Keeping the workforce and public safe as the project swirls through its cycles requires that managers be vigilant analysts, aggressive contingency planners, flexible adjusters, great communicators and effective safety trainers. Contractors say having a clearer picture of how the project will unfold is key to reducing safety risks; four-dimensional building information modeling helps reveal them. Such models create animated sequences that show a structure's components—including permanent and temporary works, major equipment and laydown areas—according to the timing of the project schedule, typically the fourth dimension in the model. Planners say 4D BIM helps them coordinate schedules, eliminate conflicts and confusion, improve training and enhance safety by design. The models can help head off spatial conflicts and safety risks that otherwise might go undetected. But useful models must be updated frequently. "It's not an easy process," admits Scott Kerr, principal BIM integrator at London-based Balfour Beatty Construction Services, which has maintained a 4D model through the life of a complex terminal expansion project at London's Heathrow Airport. The terminal is set to open June 4. The firm used the project's Autodesk Revit 3D model with Autodesk's Navisworks Timeliner, a schedule animation program, to build its 4D model. Timeliner assigns "exclusion zones" to scheduled activities and equipment locations, represented as objects in the model. Balfour Beatty updates the model and schedule regularly and runs the 4D simulation each week to create 14-day and 42-day "look-ahead" views of currently planned activities. Timeliner's conflict checker searches out clashes in space and time between equipment and trades. Activity locations are color-coded in its model, such as structural steel erection flagged for overlapping the exclusion zone for concrete placement. "When we synchronized the schedule with the model we got that flag," says Kerr. "Potentially we have an issue; something has to give." "I definitely think the value and benefits outweigh the effort," Kerr adds. "You have to manage the process, the changes and the things that come from left field, and the model can help you understand all of that—but it's a moving beast." Technology Developments Contractors, construction management firms, academics and software vendors are working on ways to improve and enhance 4D scheduling techniques. They include automated programs that check 4D models for risks and safety-code violations, based on rules such as those prescribing clearance dimensions, equipment specifications or labor allocations.
In New York City, Jennifer Downey, an architect who manages support services for Turner Construction's Integrated Building Solutions group, is collaborating with city building officials, participants in the autocodes project of research group Fiatech and the developers of Solibri software's Model Checker—a program that analyzes design models for dimensional compliance with building codes and regulations—to flag safety issues during construction.The Model Checker software runs against a BIM database of thousands of elements in a model tagged with the project's OmniClass Construction Classification System, or Uniformat, numbers. This identifies an item, such as a men's room—classification number 13-23 17 11—and the associated regulations that apply, such as Americans with Disabilities Act compliance dimensions. The Model Checker flags unclassified objects, as well as objects that fail to meet regulations. Downey has been modifying Solibri templates to set up runs for construction projects in their various phases, such as excavation or steel erection. She is tagging construction site objects in the model—such as slab edges, openings, gates, flaggers, materials storage points, portable toilets, and fire and life-safety features—to which rules apply on a construction site.
"There is a very long list of requirements for jobsite safety from different international and local authorities, as well as Turner's own requirements," Downey says. "I took the standard rule set and modified it to be safety-related. We have identified 137 items that could be reviewed in a modeling environment."In the process of modeling, participants can obtain quantities for safety materials, such as linear feet of edge-protection netting. One early payoff is in verifying the correct placement of fire extinguishers of the proper classifications—which are to be positioned within 75 ft of one another in plain sight, provide full coverage of every floor and be located within 10 ft of stairways. "For something as simple as fire extinguishers there are a lot of requirements that come into play," Downey says. Running the Model Checker against the model with fire extinguishers in place verifies their correct placement in the plans.
Mojtaba Taiebat, a Georgia Tech University researcher now at DPR Construction, also is developing rules that could be used with compliance-checking software such as Solibri for job-hazard review and to flag potential falls by analyzing openings in unfolding 4D models.Taiebat proposes his checker be used as part of a collaboration between designers and constructors in an integrated project-delivery format as early as the conceptual modeling stage, as part of a "design for safety" concept. He says a detailed schedule is not required at that stage, but modeling work locations, scaffolding, formwork, material delivery paths, openings and edges would be. "The model represents contributing factors of fall hazards and prone-to-error conditions," he explains. Once those factors are simulated and shown to the integrated project delivery team, hazards can be reduced through design alternatives, changed construction methods or altered scheduling, based on the team's experience. The Great Communicator? And then there are managers who say when teams of designers, contractors and subs watch planned work unfold on screen together, they are motivated. As they see objects representing equipment and materials coalescing through time, managers not only pick up on previously hidden conditions such as conflicts between unrelated activities, but they also understand and resolve issues in advance. "When you look at the site and say 'here is what it's going to look like next week and here's what's going to happen,' people are going to watch a video because it's cool," says Ken McBroom, chief scheduler at McCarthy Building Cos. Inc., Newport Beach, Calif. McBroom cites a hospital project on which he used 4D project management software Synchro Professional to animate the critical-path method schedule. That is when his plumbing contractor realized that planned roadwork would block a critical delivery, which was quickly rescheduled. "The plumber is not looking at the schedule of the curb-and-gutter guy. It's not his problem," says McBroom. "That happens a lot because two things don't seem to fit together." But in a 4D visualization, they do. "It is difficult and time-consuming to communicate a complex construction plan using traditional tools," adds Steve Moore, southern district planning manager for TIC, a Kiewit Corp.-owned heavy industrial contractor. "Safety personnel do not have time to study stacks of drawings or a 5,000 line-item schedule. It gets even more complicated to visualize the plan as field conditions constantly evolve and change during the project," he says. "[But] 4D gets everyone up to speed on a complex project very quickly, with detailed imagery." Moore says safety now plays a larger role in planning before the project goes to field. He says it is surprising how a safety manager can view a 4D construction plan in a totally different way than the rest of the team. "They are instantly visualizing the required fall protection, dropped-object hazards, eye-wash station locations, etc.," Moore says. "We now get detailed and substantive feedback from our safety department during early construction planning, which shapes the way that we approach our projects." On one recent powerplant project on which TIC used Synchro for 4D modeling, Moore says "the 4D model made it clear that our scheduled plan was not factoring in safety." Activities were being scheduled literally on top of others, he notes. When corrections were made the project ended up taking much longer than originally planned. "If these 4D safety observations had been fed back into the schedule from the beginning we would have had a much greater grasp of the sequence and duration of this work," Moore says. "With 4D, we can now catch these issues in our schedules years ahead of their occurrence, allowing us to create better and more realistic plans from the beginning." Jay Mezher, director for virtual design and construction at Parsons Brinckerhoff, says leveraging 4D BIM for safety follows an innovation trail he has seen with the use of computational fluid dynamics for modeling ventilation in tunnels, and evacuation modeling. Widening Use Doug Rowe, general manager of builder Lend Lease's integrated project group, says the company routinely uses 4D BIM to model and simulate detailed safety and logistics plans during risk analysis throughout projects. He predicts that as the technology becomes more user-friendly, 4D BIM for detailed installation simulations will become more common "and will clearly drive safer and more productive workflows on all construction projects over the coming years." McCarthy's McBroom says better 4D planning not only makes jobs safer but also communicates planned activities better to all stakeholders in a project, including the owners and the public. "Planning on the fly is the same as not having a plan," he says. "That's just reacting. When you are trying to plan on the fly … that's usually when something goes wrong." McBroom says one scenario in which he intends to use 4D modeling to enhance safety is during mixed-skin construction on multi-story buildings. The company just finished one such project. It tracked the day-to-day work locations on the face of the building of construction trades workers doing masonry, framing, panel installation and glazing with color markers on isometric 2D plans day after day. He said he realized as they wrapped up the project that modeling those locations using 4D would help ensure that no activity violated one of McCarthy's fundamental safety rules, which is that if crews are working overhead, nobody is underneath. "The application of 4D to that is perfect. I don't have to look at a CPM schedule and try to imagine where every crew is; I can look at the [4D] representation of the model at any point in time and see what crew is working on what level. That would be a great application of 4D and safety," McBroom says. Safety, Translated Experts say visualizations can be very effective for communicating life-safety information—especially to non-English speaking workers. Ricardo Khan, director of integrated construction at Mortenson Construction, is working with Caroline Clevenger, an assistant professor at Colorado State University, to draw site- and task-specific bilingual visual training tools directly from 4D models of planned activities. They are starting with scaffold erection, with its significant fall hazards, and are visually drilling into the activities to train novice and non-English speaking construction workers, whose injury rates far exceed other categories. Clevenger notes also that Hispanic construction workers are twice as likely to be injured on the jobsite as non-Hispanic workers. She says research suggests the higher injury rate is due, in part, to language and cultural barriers on site. "I would like to see future efforts of 4D modeling begin to focus on a micro level," says Ryan Poropat, a Mortenson superintendent who recently used 4D tools on a sports and entertainment center in Buffalo, N.Y. Their efforts are in line with another 4D BIM- related mission of Jason Reece, a Balfour Beatty research and development leader based in Fairfax, Va. He has studied the industry's long-running failure to communicate critical safety knowledge about construction risks, such as trenching. Like Clevenger and Kahn, Reece sees an opportunity to improve training through BIM-enabled visual storytelling, which, combined with personal stories about real incidents, can help create "the written, audio and visual hooks that make information stick," he says. Creating realistic visualizations of high-risk scenarios in the context of the work, and then showing how hazards should be mitigated, is a powerful way to leverage technology for safety, Reece says. He suggests that if safety trainers take advantage of BIM and visualization to improve safety-related storytelling, their training will have more effect. "Create the mental hooks for the information; that's how people remember and how you are going to change safety culture," Reece says. Stories are information. "If you want to use BIM for safety you have to learn what makes a good story and what makes ideas stick." Full article here: http://enr.construction.com/technology/bim/2014/0602-Dynamic-Models-for-Safer-Sites.asp?page=2