Digital Platform based Shop-drawing assessment
Construction Information Management has been an interest of mine for a good 30 years.
Over this time I become a fairly competent BIM implementer and had been involved with some pretty large projects all over the world. While I missed the glory of the almighty BIM projects supported by the BIM-cream of the industry and stayed out of the limelight of the mega-ambitious and fake attempts to speedily BIMitize the global industry , I’ve had the pleasure of delivering some very cool and cutting-edge stuff.
While BIM is all about the ‘I’ of the Information, BIM or no BIM, when it comes to Construction Information Management, one issue keeps failing to get enough attention.
In the attempt of fixing the industry in one big swoop is, the workflow of producing and managing shop-drawings by numerous construction participants based on design documentation in a pretty archaic way seems to be generally overlooked..
This is the case even in the majority of otherwise BIM-mandated projects, though a parallel, quasi-sophisticated modeling workflow may exist, for ‘show’.
The shop-drawings, that end up used for building off are still, more often than not, 2D based drawings (regardless of their origin) and get assessed and approved (or rejected, corrected and then approved) by client-appointed parties, in a tedious, long-winded way before they are let to proceed to construction.
Regardless of the skills and qualifications of the assessors, or even time spent on these exercises, experience shows, that there is an unfortunately large number of issues buried within these shop drawings, that do not get unearthed in the assessment process and end up going to the construction to be resolved on site.
Luckily, there exist an approach practiced by some on the fringes of the BIM fraternity that helps with this issue.
This particular approach, described below is also shown graphically here: http://www.slideshare.net/zolnamurray/3-dplus2d-rev2
The way construction projects usually work, (design – tender – build, for example) the contractor submits the shop-drawings, the technical team, either the design consultant or someone independently appointed by the client, assesses, comments and returns for amendments or approves for implementation.
The process is linear and mostly broken over disciplines.
The various assessor engineers typically work with flat (2D) PDF or AutoCAD files, and consider individual sheets, marking them up or adding comments. Sometimes, but not always they overlap various sheets from their own disciplines (digitally or just over the window glass) and sometimes, but not always they cross check information against other disciplines.
Due to the large number of shop-drawings, each assessor is pressed to process each sheet in the shortest possible time and there rarely are processes in place to capture typical issues that may impact on future packages.
The results are often missed technical problems of spatial coordination or the nature of ‘under developed-design’ that will have to be resolved on sites at more cost and time delays than necessary.
While a truly functional BIM would probably fix these problems, the strategy described here is by no means a ‘pure BIM approach’ but rather a ‘hybrid’ one.
For the example to explain the methodology on, a set of buildings is used, part of a development completed a couple of years ago, where the number of shop-drawings created went into thousands. (in fact close to or OVER 20 thousand! Or was it 35.000+?)
It is also important to state, that the concept works on both very small and extremely large projects.
The process starts at the point where shop-drawings get created and submitted by contractors for assessment.
The assessment team (appointed by the client) is expanded from the usual cocktail of specialist-engineers with a new position, that of the Virtual Assessment Model Manager.
This person will work closely with all the individual discipline engineers, but also manage the Platform, the center feature of the Digital Project Environment.
At the outset of the project, the Manager sets up the ‘ghost structure’ within the platform. This structure has the digital equivalents of the key spatial drivers of the ‘real’ project, grids, stories and the positions of section and elevation lines matching the ones on the drawings.
The main elements of the ghost framework are grids, sub-grids, section-elevation lines and stories. These combined define the 3 dimensional skeleton of the project. It is important to understand that these elements are intelligent objects, not just lines, circles and text.
It is the digital skeleton of the building and it is critical for it to be as accurate as it is possible.
The next step is to feed onto this Digital Platform the shop-drawings as they become available. There is no hard rule on the order of imports, but it is logical to follow that of the construction’s needs, so starting with foundation drawings makes sense. As the shop drawings arrive, the Model Manager places the sheets within the ‘correct place’ of the Virtual Environment on the Digital Platform. Plans over the appropriate grids, elevations, sections in the right planes, specific details in their original positions.
The Model Manager, given the correct software has numerous tools to assist the work with large number of drawings, going into hundred and even thousand, including filters, layers, views and work spaces.
While not all drawings can be placed in a specific spatial position (i.e. typical, generic details, schedules etc) there is always area within the Digital Environment for these to be stored and referenced from.
The Model and the Digital Platform are continuously available to all assessors, so they can review these drawings almost as soon as they have been placed within the Platform. Drawings from one discipline can be referenced to each other or against other discipline straight from the beginning of the populating of the Digital Environment.
Parallel with the placement of received shop-drawings, the Model Manager creates the virtual model of the building(s) itself on the Platform, constructing it up in a similar sequence to that of the real construction. This developing model is another feedback to the accuracy and completeness of the shop-drawings and provides up-to date information to the assessors to act on in a timely manner.
The beauty of the Platform is that one can have numerous buildings in one file or closely referenced to each other as well as it all been centrally located and updated.
Should there be contractor supplied 3D (shop-drawing) models available as parts of submittals, the Model Manager has the ability to import them as well and assesses their integrity against the live model and all the other shop-drawings.
The Digital Platform should be user friendly and offer many tools for visual assessment like, traces, sliders, colours, modifiable transparency etc etc.
On the first look, the interface of the Digital Platform presented here is pretty similar to any CAD (or BIM) interface. It has a ‘model space’ type of area with a square grid and is also equipped with what looks like a 3D window. While the approach is somewhat software-agnostic, the global AEC market has a lean offering of platforms that are well suited for the simultaneous manipulation of (many) 2D drawings and one or more live 3D models.
Here, Graphisoft’s platform is used and it is not unusual for it to carry 200-500 drawings dynamically linked in within a complex, construction level, detailed 3D model.
For more information on this approach, check out the supporting PP: