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:
http://www.slideshare.net/zolnamurray/3-dplus2d-rev2
