Kirsty Hogg, technical BIM lead at Cundall, and Coral Butler, senior BIM manager at Mace, discuss how an Autodesk-based federated model and a cloud-based reporting system ensured better collaboration between the consultant and the contractor and materially improved the workflow of a recent project.
A federated solution
Looking to improve the problem solving and communications for the third phase of a three campus data centre project, Kirsty Hogg from multidisciplinary engineering consultant Cundall got together with her counterpart, Coral Butler at international construction company Mace, bringing the contractor into the design process at a much earlier stage than previously considered.
The federated model was developed in Autodesk using Revit as the main modelling software with Navisworks to interrogate the Revit model. As an assembly of models from other relevant disciplines, including architecture, civil engineering, landscaping, underground and structural, M&E, public health, security and data services, the federated model was able to house information useful to a variety of other disciplines in a single, connected workflow.
Hogg explains: “Ideally the earlier the engagement with the technology, the better the model. If we can involve the other disciplines, asking them what software they are using and the information they need, before the 3D model is started, the information can be built into it from the beginning. Having software conversations earlier makes the model more bespoke and useful.”
Supported by a cloud-based reporting system – based on a not-so-simple spreadsheet template – the federated model was used to identify a range of problems, such as physical clashes and workflow issues, early in the design process and therefore reduce any remedial work required and the resulting budget and time issues.
“We’re able to head problems off before they go to fabrication—that’s saved everyone time, money and grief,” says Hogg.
Designers, contractors, clients, and other stakeholders were able to follow the changes over time and the model could be used to produce detailed reports for coordination meetings.
Explains Butler: “Because we put in details such as materials, we were able to see the finishes and colours and create virtual reality walk-throughs. These were so much easier to present to clients and subcontractors, who could see the finishes required.”
Efficient and detailed
During the project, it was found that feedback from the field could be entered extremely efficiently into the model, improving its accuracy and consistency across the site.
As a 3D model, it was also particularly useful for showing the space available, so, for example, clearance zones could be established for air flows or to allow room around equipment for maintenance or cleaning. For a consultant this might not be important, but to the facility maintenance team, it was vital.
Consistency – with all the disciplines using the same model and families – was much improved especially as certain parameters could be “set” across the site. For example, clearances for steelwork could be set to avoid them being impacted by concrete pouring or beams. Or, for foundations, potential loading issues were addressed by putting in “worst case” scenarios.
The federated model encouraged engineers to be more interactive with other disciplines, by almost literally joining up the dots.
Explains Butler: “By allocating matching IDs to any element that came up through the floor slab and each internal system that was due to fit on to it, it was easy to identify which system had to fit where, and identify any potential conflicts.”
Security fencing was another example of how a relatively small addition to the model had big benefits. Normally done only in 2D, it was included in the 3D model, allowing clearance zones for the foundations to be shown in relation to where the other services were due to run.
A 1.7m “exclusion zone” was established for all fences, foundations and posts, across the project. Navisworks could then be used to search for the zones and see what, if anything, was conflicting with or impeding them.
Comments Hogg: “This is the first time we’ve used this idea for anything other than access zones, but it’s identified and prevented so many clashes that we’ll definitely take it forward to other projects.”
Leaving a legacy
With the early engagement of the contractor with the design process, the information the federated model contained was more detailed, relevant and valuable. So, rather than throwing away the model, the collection of historical data could be handed straight to the contractor, who used the model going forward so avoiding having to start modelling again at each build stage.
Once the project had been handed over, the ability to keep the model and the reporting gave a large but accessible amount of legacy data. In addition to a smoother handover, this large-scale knowledge transfer provided support for sub-contractors who could see when and how a decision had been made.
Butler says: “Designing and building a project should be one unbroken process. There should be an ongoing relationship rather than just a brief handover!”
Head in the clouds
The design of the online reporting system stemmed from what data could be extracted from the federated model and how it could be interrogated.
Butler admits: “I supplied the bare bones of a Google template and now it’s grown into a beast.”
The level and comprehensiveness of the information available in the reports meant that actions could be drilled down into extreme detail, for example by contractor or by room. Everything could be measured and it was simple to identify which teams had outstanding actions and quickly identify problems such as lack of resources or training.
Reports could be generated in the most relevant format, such as charts, graphs, colours, which helped reporting to other consultants. For example, a report to the architect could be broken down by zones to give them a clear and precise breakdown of clashes within each zone.
One unexpected result of the intensive use of the federated model and the reporting was an improved consistency of modelling across the whole team. Because the report could extract details of which had more or fewer clashes, subcontractors could reassess how well or poorly their own models or coordination were doing, and encouraged them to review the quality of their own work.
“Building relationships is key; the model and reporting has the ability to make the workflow more transparent and efficient, but should not be used to play the blame game or finger pointing. Respect fosters open discussion and better problem-solving,” says Butler.
The reporting continued from design stage to construction which gave an audit trail throughout the project’s build life.
What next?
Architects have traditionally taken the lead on BIM design, but the drawback is usually that the software they use is more tailored for the architects’ needs than an M&E consultant or contractor.
“Perhaps the BIM process would be better led by a consultant with a broader knowledge of what other disciplines are likely to need in their models,” says Hogg. “Architects tend to leave out elements because they don’t know what M&E consultants can put into the model, leading to later problems.”
The software of BIM is progressing rapidly; already Autodesk 360 is building into its new versions some of what Hogg and Coral had been doing manually such as inputting values. Contractors, consultants and architects are earnestly either upskilling their workforce or recruiting BIM trained staff. But something is missing.
Butler explains: “It takes time – and time at the front end of a project – to build in the design elements. Even though adding solutions to the beginning avoids paying for remedial works later, many companies are either unwilling to invest the time (and increase the expense when fees are tight) or are not investing in the levels of BIM skills required to make their models more intelligent – and more able to create a design that can be built to time and to budget – without overruns.”
Hogg concludes: “We’re pushing the boundaries. We know there is more scope for this to be expanded, yet to do so would need a change in the fee structure to allow more time for early integration and to develop ideas and collaboration.”
The benefit in applying BIM in pre-construction with the contractor’s early input, and in the increased collaboration and knowledge sharing that it provokes, is obvious in the federated model’s ability to identify problems before they become problems, improve communications, smooth the workflow and create a legacy of useful and useable data that can help across all the stages of the build.
As the best way to keep the client happy is by progressing their project on time and on budget, using BIM to foster the early collaboration between the consultant and the contractor should be more “business as usual” than “a nice to have”.
