CC3001

CASEstudy
BS1192:2007. A fully federated 3D model
of the scheme was to be produced and
maintained throughout the duration of the
scheme, and used for coordination, clash
management, communication and
buildability.
3D Services Models, both existing and
proposed, were to be modelled with high
accuracy on the Eastern section of the
scheme. Models were also set up for
temporary works such as traffic
management and structural pads, with
particular emphasis on the M1 - this is
the first project to involve the creation of
a link road to a busy, managed, section
of a motorway). 3D models of existing
conditions were also set up to coordinate
permanent and temporary works.
A 4D programme model and 5D cost
model were to be embedded within the
model; 4D to visualise construction
methodologies and ensure buildability,
and 5D for target and projected costs,
integrated into the model using attribute
data. A 6D Asset model was projected
for use in future Highways England
projects. Finally, the BIM lessons learned
were to be collected and documented for
use with future projects.
OUTCOMES
The reaction to the BIM processes from
all team members was positive,
particularly when they realised that the
deliverables were the same as those they
expected from traditional methods. That
was helped by the way that the BIM team
led by Adam and developed by David
Bennison's team, simplified its
introduction by creating templates
through which they could access the
parts of the application they needed,
where to enter data and where to find the
results, guiding them through unfamiliar
processes. The templates were tested
and saved as operational manuals, and
different operational guides were
developed for each discipline - a
substantial task, but one which enabled
engineers unused to BIM to find their way
through each process.
To satisfy 4D and 5D requirements, a
classification system was established
based on the Manual of Contract
Documents for Highways Works Volume
4 Section 3, which contains a library of
standard item descriptions for Highway
works. This is the traditional classification
used by the teams and the basis of the
Highways Work Breakdown Structure
(WBS).
Two problems became evident. The
filenames and levels required to classify
the 3D objects in such a complex
infrastructure project involving a number
of different technologies, and many
composite objects that could comprise
numerous elements. A drain chamber, for
instance, could contain 20 different
classification systems, each requiring a
different filename and level - ultimately
amounting to many thousands of levels.
This was addressed by treating each of
the object elements as attributes, a far
more sensible way of handling a
multiplicity of information, made feasible
by the improved hardware, processing
power and search algorithms. As a result
one level or layer became sufficient to
contain all associated data, including
cost and materials, as attributes.
The second issue involved the
classification of processes that were not
easily quantified as cost or time
elements, such as the creation of
earthworks, the digging of ditches, the
creation of slope angles and so on. Each
engineering discipline had its own share
of indeterminate processes.
The solution was to create specific
properties that could be quantified, such
as storing the cross-section area of the
object as attribute data and then dividing
it into the volume to obtain its length,
which is the required unit of
measurement and which, therefore, could
be costed. These Bill of Quantity (BOQ)
elements had a description, units of
measure and a formula, and were linked
to the list of rate tables for calculation
purposes.
SOFTWARE CONSIDERATIONS
Because of the lag between the original
planning for the project and its restart,
much of the information was held in older
versions of Bentley's software such as
MXRoads, which caused problems
because of its incompatibilities with
MicroStation. In a bid to prevent similar
problems from a multiplicity of project
members bringing along their own
software solutions, the number of software
vendors involved in the project was kept
to an absolute minimum.
The increased functionality required for
the 4D and 5D modelling was provided by
Synchro because of its ability to handle
.DGN files and other functions that the
processes required, some of which could
not have been addressed by using
iModels.
Bentley's ProjectWise was instrumental in
developing the templates that assisted the
project teams, and in managing the
sharing of information between the
Bentley civil engineering applications
used.
In all, the exercise of implementing a BIM
system in parallel to traditional working
processes validated the benefits that
could be accrued from such a process,
and provided a basis for all future projects
involving each member of the team.
www.bentley.com
January/February 2017 29