3 d and 4d modeling for design and construction

1. 3D & 4D Modelling for Design and Construction-
This paper discusses how to form a team for successful implementation of 3D and $d modelling for design
and construction of projects to realize the benefits of these technologies and impact the project
execution to achieve-
- the elimination of field interferences,
- less rework,
- increased productivity,
- fewer requests for information,
- fewer change orders,
- less cost growth, and
- a decrease in time from start of construction to facility turnover
This is explained using 2 examples of projects on which the authors have worked - Camino Medical Center
in Mountain View, California; and Sequus Pharmaceuticals Pilot Plant Facility in Menlo Park, California.
The Camino Medical Group Project-
- Project Organization – The Owner along with AEC team prequalifies MEP/FP subcontractors. A
detailed guidelines to prequalify subcontractors is created which requires them to be adept at
using 3D/$d coordination and collaboration tools.
- Modeling Responsibilities – Architect provides the architectural and structural 3D model, and
MEP/FP subcontractors use it to create the MEP/FP model. GC responsible to coordinate with
MEP/FP for creating their 3D models and do clash detection. MEP/FP subcontractors agree to
develop their design using interoperable 3D/4D design tools. MEP done using Lean Construction
principles. MEP people involved in the project from very start and coordinated with Design team
giving inputs for a better design.
The Sequus Pharmaceuticals Project-
- Project Organization - GC assembled the design build team for design and construction of this
project. Again the AEC and MEP/FP were selected on the basis of their experience in 3D
modelling experience on past projects. Each member of team agreed to make 3D CAD drawings
for their respective trade using a design-build approach.
- Modeling Responsibilities – Design form for creating 3D model of architectural scope of work; GC
for managing different MEP/FP trades for design coordination and construction; Engineering firm
for creating basis of structural drawing for MEP; and MEP subs did detailed design and 3D
modeling for their scope of work
2D vs 3D modeling process- 2D process uses printing drawing related to different trades on transparent
sheets and placing them on top of each other under a source of light, and then redlining is done to make
necessary corrections. This process is time consuming and inefficient as many problems arise during
execution of these drawing on field which leads to RFI, change orders and delay etc. Doing all these works

2. in a 3D environment has a distinct advantage as 3D gives an extra dimension to collaborate in, and thus
avoids problems down the line.
3D Design Coordination Process-
- Identifying the potential uses of 3D models on a given project and identifying the specific uses
that will be implemented
- Identifying model requirements – It includes Identifying the modeling responsibilities for the
various scopes of work; Establishing the scope of the 3D modeling effort and the level of detail to
be modeled; Establishing the work breakdown structure; and Creating a schedule that identifies
key modeling activities
- Establish the Drawing Protocol – Project Point Reference (0,0,0); file naming; version control;
color scheme – helps set a uniform system for all trades and makes coordination easy, also helps
in combining different models together.
- Establishing conflict resolution process – defining which softwares will be used so facilitate
interoperability; establishing file sharing platform etc.
- Develop Protocol for addressing Design Questions – Protocol should be such that middleman are
avoided. Questions should reach the specific party directly
- Develop discipline specific models and integrating these models together and then using them to
identify conflicts between components/systems – interoperability of softwares used plays an
important role here which will avoid rework and delay.
- Identify solutions for conflicts that came up and documenting these conflicts and solutions in an
effective manner
Lessons Learned-
- Project teams should determine the stage in the design development process when a specific
scope of work should be modeled in 3D
- Project managers and executives committing to a team-oriented approach should carefully
assemble their project staff
- Assemble teams so that the designs are created by the participants who have the construction
expertise to create constructible designs, and who are responsible for installation and can
leverage the designs throughout construction
- Every essential trade on the project should put their design (scope of work) into the 3D model to
leverage the benefits of electronic 3D design coordination
- Project teams modeling in 3D require increased design and coordination time. Although this is
offset by benefits in construction, it does need to be addressed in each discipline's estimate and
contract
4D Construction Coordination Process- One of the goals of the coordination process on projects is to limit
the interaction between the subcontractors installing the different systems so rework could be avoided
and productivity maximized. The 4D model is used for this purpose. Following 6 steps are identified as
essential to developing a coordinated and detailed 4D model for construction coordination.

3. - Establish Work Breakdown and Flow
- Establish Installation Sequence
- Reorganize 3D Models
- Refine Schedule
- Link 3D Objects and Activities
- Refine 4D Model
Benefits of 4D Modeling- 4D model assists with coordination of subcontractor schedules; 4D model
clearly communicates schedule intent; 4D model communicates work flow over time; 4D models help
identify constructability issues and sequencing problems prior to construction; and 4D models show the
status of construction at any time in the project
Lessons Learned –
- It is important to determine the purpose of the 4D model as it dictates the level of detail required
by the 3D model and the schedule
- Try to set up the 3D model to facilitate 4D modeling whenever possible
- 4D information should be continuously updated
ROOT CAUSES OF CLASHES IN BUILDING INFORMATION MODELS
BIM coordinators use the term ‘clash’ to refer broadly to one of several kinds of spatial conflicts
discovered in a BIM, that is, they characterize the clash based on the nature of its existence. For example,
they differentiate ‘hard clashes’ from ‘soft clashes,’ and ‘time clashes’. Clashes are like problems
discovered at the end of the assembly line, before the product is released to the customer. The assembly
line is the design process. The customer can be anyone involved in procurement, fabrication,
construction, or operations. Clashes point at conflicts that demand the attention of Last Designers and, as
needed, also of others in the project delivery process.
- A ‘hard clash’ refers to one building component physically yet unintentionally penetrating
another building component
o The paper discusses many inherent causes of error that are caused due to negligence or
left knowingly due to some situation at hand. Various causes of hard clash are – design
uncertainty (designer is not certain about how exact component looks like and thus
places a dummy components in its place to check on it later); failing of design rules;
design complexity; design errors; and Balancing effort in resolving the dilemma between
model accuracy vs. meeting a deadline (this is one of the most out of the text thing that
happens in real world scenario)
- A ‘soft clash’ (aka. a ‘clearance clash’) refers to components (subsystems) that are closer than a
certain distance (a minimum clearance) from one another
o Things that cause hard clashes can also lead to soft clashes and vice versa. It may be
caused by - Blocking out space surrounding the physical volume occupied by an object
which can be caused by various reasons like rough level of detailing as per LOD

4. requirements, uncertainty in the type of component to be used at a particular place,
rough positioning and geometry of various components etc.
o Clash Detection vs Clash Avoidance - Clash detection is a reactive, after-the-fact approach
whereas Clash avoidance is proactive.
- A ‘time clash’ refers to spatial challenges (components potentially occupying the same space)
anticipated when considering constructability or operability of the facility.
o Model based sequencing and scheduling can help in avoiding time clashes
- All these clashes have considerable effect on the design, constructability and building
performance quality of the project.
Lean construction principles and tools facilitate planning and control, maximize value and minimize waste
throughout the construction process. Clash detection—the identification of waste—is a justified process
in lean project delivery. Fleeting in nature, clashes must be made visible, characterized, and have root
cause(s) identified. We must develop systematic ways to constructively improve design processes so as to
reduce future occurrences of clashes. Thus, BIM proves as a viable tool for Lean Project Delivery, and has
a significant impact in lean construction practices.