CU Jan-Feb 2020

INDUSTRYfocus
BIM on the building site
David Chadwick and Excitech's Daryn Fitz continue their discussion of BIM by evaluating its impact
on main contractors' working practices
David Chadwick: How are main
contractors using Building
Information Modelling (BIM)?
Daryn Fitz: Where designers are using
BIM to support design outputs and
assist in producing coordinated
designs, main contractors are
combining processes to improve
project outcomes. For instance, 3D
point cloud survey data and the
designer's 3D models can be federated
together in a product called Navisworks
along with a plugin solution called Verity
which analyses the combined data. It
can report on components that are out
of tolerance, not yet installed, or simply
not installed in accordance with the
design model.
The advantage of this approach is that
critical elements such as a building
façade can be checked against the
constructed structure and the proposed
design to ensure a 'right first time install'
is achieved, avoiding delays to the
construction programme and increased
costs in material and labour. Checks
can also be made for the positioning of
builders works holes and slab
penetrations, giving confidence to the
building services subcontractor that any
off-site fabrication will fit within the main
frame of the building.
Models can also be linked and
synchronised to construction
programmes providing a solution known
as 4D planning (3D + Time) which
allows the proposed construction
programme to be viewed in 3D. This
approach not only helps to visualise the
build and communicate it to others, but
also identifies errors in the sequencing. I
myself have worked with main
contractors and delivered over 340 4D
planning sequences, and each time
either errors in sequences were
identified or alternative construction
options and methods were proposed.
Another great use of 4D sequencing is
to visually track progress of the building
on the site to ensure that the positioning
of temporary works equipment and
structures are all aligned to the program.
In addition to the above examples
there's also clash detection, where 3D
design models are federated together
in products such as Autodesk's
Navisworks and are analysed to ensure
that all components are coordinated
prior to construction, and maintenance
access is considered and reviewed.
As mobile technology is becoming the
norm on our sites, we are seeing the
use of the 3D model playing a
significant visual aid to our site
operatives. Using tools such as BIM 360
Build enables us to navigate around the
model out on site and allows us to see
the virtual completed state within the
progressive construction environment.
This also gives us the advantage of
bringing in the assets from the model
into a digital platform while looking to
enhance quality and compliance
procedures via digital forms.
I believe that the advantages BIM
provides are compelling, and the above
are just four examples from a very long
list of applications.
24
January/February 2020