NORTHEASTERN UNIVERSITY Thesis Title: Developments in Cost Estimating and Scheduling in BIM technology Author: Xinan Jiang Department: Civil & Environmental Engineering Approved for Thesis Requirement of the Master of Science Degree in Civil & Environmental Engineering Thesis Advisor (Professor Ali Touran) Date Thesis Reader (Professor Asli Pelin Gurgun) Date Department Chair (Professor Jerome F. Hajjar) Date Graduate School Notified of Acceptance Director of the Graduate School Date
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NORTHEASTERN UNIVERSITY Thesis Title: Developments in Cost Estimating and Scheduling in BIM technology Author: Xinan Jiang Department: Civil & Environmental Engineering Approved for Thesis Requirement of the Master of Science Degree in Civil & Environmental Engineering Thesis Advisor (Professor Ali Touran) Date Thesis Reader (Professor Asli Pelin Gurgun) Date Department Chair (Professor Jerome F. Hajjar) Date Graduate School Notified of Acceptance Director of the Graduate School Date
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DEVELOPMENTS IN COST ESTIMATING AND SCHEDULING IN BIM
TECHNOLOGY
A Thesis Presented
by
Xinan Jiang
to
The Department of Civil & Environmental Engineering
in partial fulfillment of the requirements for the degree of
Master of Science
in
Civil & Environmental Engineering
in the field of
Construction Engineering & Management
Northeastern University Boston, Massachusetts
August 2011
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Table of Contents Abstract .......................................................................................................................... 3
List of Figures ................................................................................................................ 5
List of Tables .................................................................................................................. 5
3D surface and shape formats vary according to the types of surfaces and edges represented, whether they represent surfaces and/or solids, any material properties of the shape (color, image bitmap, texture map) or viewpoint information
3D Object Exchange formats Descriptions STP, EXP, CIS/2 Product data model formats represent geometry
according to the 2D or 3D types represents. They also carry object properties and relations between objects.
Game formats Descriptions RWQ, X, GOF, FACT Game file formats vary according to the types of
surfaces, whether they carry hierarchical structure, types of material properties, texture and bump map parameters, animation and skinning
GIS formats Descriptions SHP, SHX, DBF, DEM, NED Geographical information system formats XML formats Descriptions AexXML, Obix, AEX, bcXML, AGCxml, IFCxml
XML schemas developed for the exchange of building data. They vary according to the information exchanged and the workflows supported.
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2.1.3 LEVEL OF DETAIL
According to Bedrick (2008), Level of Detail (LOD) of BIM models are defined as
“the steps through which a BIM element can logically progress from the lowest level
of conceptual approximation to the highest level of representational precision”. Five
levels of detail are determined to describe the BIM models, which are named from
Level 100 to Level 500: Conceptual, Approximate Geometry, Precise Geometry,
Fabrication and As-built. Table 2 provides LOD definitions in different project phases
(Bedrick 2008, Leite et al. 2010). As the project progresses, the LOD of the models
will be going to a higher level and the richness of the information will also be
improved. It requires the cooperation among all parties involved in the project such as
architects, estimators and schedules. Each party will embed the information in the
model based on its own requirements.
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Table 2 LOD definitions (Adapted from Bedrick 2008, Leite et al. 2010)
Structures™ is capable of supporting large models, even with multiple users operating
concurrently by its Multiuser Server. This Multiuser Server is developed by Tekla
Corporation and can support a maximum of 40 users operating simultaneously.
However, since the concurrent operation from multiple users is more complicated than
a single user operation, these users need to be highly skilled to fully utilize the
complex functions of this software.
2.3 BIM Application Areas
As section 2.1 indicated, BIM model is parametric-object based and all the
information stored in the model can be shared and reused by different stakeholders
involved in the building lifecycle. By storing and exchanging the information of the
building automatically, BIM model can provide more accurate data and information of
the building. BIM technology can be utilized in different application areas such as
design/modeling, energy analysis, clash detection, cost estimation and construction
scheduling. These multiple application areas in BIM can help users to improve the
communication, reduce errors, and potentially save time and money. This section will
explore important BIM application areas in various phases of the building lifecycle.
Design/Modeling
The object-based parametric modeling feature in BIM allows architects, MEP
engineers, structural engineers and fabricators to leverage multiple functions on the
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same building model for their own use. With accurate building information and object
models, the design/modeling process is dramatically facilitated. The design accuracy
and information sharing enhancement span all the phases of the design/modeling
process which also benefit the subsequent activities such as accurate quantity takeoffs
that can be used in cost estimating and the construction phase can be automated for
the project control.
Energy Analysis
The capability to link the building model to energy analysis tool allows users to
conduct the energy analysis in the early design phase. Traditionally, a separate energy
analysis would be conducted at the end of the design process and it is not possible for
users to modify the design to improve the building’s energy performance. By using
BIM technology, the building model can be linked to energy analysis tools for the
energy evaluation during the early design phase. The analysis allows users to make
energy-conscious decisions and to test the energy-saving ideas without postponing the
design process (Stumpf et al. n.d.).
Clash Detection
The designs from all organizations can be brought together and compared, and the
geometric clashes between architectural, structural and MEP systems will be detected,
checked and modified. Coordination among different organizations is enhanced and
errors and omissions are significantly reduced, thus speeding up the construction
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process, reducing costs, minimizing the likelihood of legal disputes, and shortening
the construction period.
Construction Scheduling
The design and the construction schedule can be synchronized by linking the building
model to the project schedule. It allows users to simulate the construction process and
show the virtual view of the building and the site. More details about construction
scheduling will be provided in the following sections.
Cost Estimating
BIM users can generate accurate and reliable cost estimates through automatic
quantity takeoff from the building model and get a faster cost feedback on changes in
design. It is possible to make all the involved organizations aware of the cost
associated with the design before it progresses to a more detailed level. The following
sections will provide more detailed discussions about cost estimating in BIM.
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Chapter 3
BIM and Construction Management
It has been widely accepted that construction management skill of the contractor is the
hub of the construction process, and any activities and decisions made by contractors
during the construction phase will influence the productivity and cost of the whole
project. It has been reported that as much as 30% of the cost of construction is wasted
in the field due to coordination errors, wasted material, labor inefficiencies and other
problems in the current construction practice (CURT 2002).One of the benefits in
BIM is to limit the above inefficiencies, thus enhancing the productivity and reducing
the project cost. According to Gallaher et al. (2004), the estimated “cost of inadequate
interoperability in the U.S. capital facilities industry is $15.8 billion per year” and the
AEC industry are targeting to reduce this $15.8 billion losses by providing a more
integrated project life-cycle. In this chapter, the utilization of BIM in construction
management will be discussed with special emphasis on scheduling, cost estimating
and project controls.
3.1 Project Scheduling in BIM
Project scheduling (4D modeling) in BIM is to link a BIM model to a schedule to
visualize the schedule of the construction. The use of scheduling function in BIM (4D
Model) can help the users establish optimized schedule of the project in a 3D
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environment which also allows the users to have a virtual view of the whole project.
The concept of 4D Model was first mentioned by Egan John (1998) that “certain
principles and management techniques could successfully cross-over from other
industries like manufacturing to serve the project delivery demands of the
construction industry.” Koo and Fischer (2000) developed a 4D model for a
commercial construction project. They were able to find the incompleteness of the
original schedule, detected the inconsistencies in the level of detail among the
schedule activities and discover the impossible schedule sequence. They proved that
4D models are able to evaluate the effectiveness of the project schedule and
anticipated the future improvement in 4D tools. The experiment of Songer et al. (2001)
focused on the 3D/4D visualization on project schedule review and the results
provided quantitative evidence of the advantages of 3D/4D representations for
schedule review for improving construction projects. Kamat and Martinez (2001)
proved that visualized simulation could significantly improve the effectiveness in
construction operation; however, the supportive software tools were still not available
in the market. They also provided the first version of a general-purpose 3D
visualization software tool of construction operations. Clayton et al. (2002) showed
that “3D modeling and computer simulations provide new ways for architecture
students to study the relationship between the design and construction of buildings.”
Heesom and Mahdjoubi (2004) provided emerging research initiatives in 4D CAD by
“identifying three research areas: product modeling and visualization, process
modeling and analysis, and collaboration and communication.” Mallasi (2006)
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developed a new concept for “visualizing workspace competition” between the
progressing activities. The 4D simulation tool, which was named PECASO, provided
a dynamic 4D simulation environment to analyze workspace congestions among
progressing activities. De Vries and Harink (2007) described a method for automated
construction planning and provided an algorithm that derived the construction
sequences from a solid model of the building. Finally, a perspective view was
presented on a more advanced and automated planning method which includes
contractor’s professional knowledge for more accurate results. Jongeling and
Olofsson (2007) presented “a process method for the planning of work-flow by
combined use of location-based scheduling2
2 Location-Based Scheduling: Location-based Scheduling uses production lines in a linear scheduling method (LSM) to represent work performed by various construction crews that work on specific locations in a project (Jongeling et al. 2007).
and 4D CAD.” They also suggested that
a location-based scheduling could improve the usability of 4D models and 4D models
could enhance the value of location-based schedules. Kang et al. (2007) proposed a
web-based 4D CAD to enhance the collaboration during construction scheduling
process. Jongeling et al. (2008) presented that the application of 4D is a promising
approach to extract different types of quantitative information from 4D models for
time-space analyses of construction operations. The paper also showed how to extract
different types of 4D contents from 4D models for project planning purpose. Young et
al. (2009) delivered surveys of thousands of AEC participants such as Architects,
Engineers, Construction Managers, etc. in the U.S to evaluate the market value of
BIM technology. The report showed that almost 50% of the industry is now using
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BIM and some users currently experienced value from 4D scheduling of BIM, which
was also one of the main future development areas in BIM (Park et al. 2011).
In the following section, project scheduling process in BIM will be discussed. Users
can choose from a variety of software tools which can support the 4D model functions
of BIM. They are: i) Manual method using 3D or 2D tools, ii) Built-in 4D features in
a 3D or BIM tool and iii) Export 3D/BIM to 4D tool and import schedule. The main
focus in this section will be on the last two options of the methods.
BIM tools with 4D capability
As stated above, two main 4D scheduling methods will be discussed in this section—
i) Built-in 4D features in a 3D or BIM tool and ii) Export 3D/BIM to 4D tool and
import schedule. The first method is to assign the “phase” of a BIM object to the
object property or parameter—adding the “phase” parameter to the BIM object. In the
building design, architects may need to create multiple design phases—“existing” and
‘new construction” phases for renovation projects or “demolished” phase for
temporary construction, or define the basic timeline of the project during the design
phase. This will require the built-in 4D capability in BIM software tool which will
allow users to assign simple phases to the building model. For example, in Autodesk
Revit Architecture™, users can define the project phases such as Existing, New
Construction and Demolished (Fig.7) or by timeline such as March 1st or by the end
of March under the Project Phases Tab. The BIM objects in Revit Architecture™
could be assigned to these phases, and the phase works as the 4th parameter of the
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model—4D model. As an example, in Figure 8, the Curtain Wall in the building
design is selected and under the Properties dialog, the Phasing Category is shown. The
selected Curtain is assigned to the “New Construction” phase in this project. When
the building model is completed, users can get a straight-forward breakdown of
project phases generated by Revit Architecture™. Users can also apply filters to show
the objects in a specific period of time or in a specific phase. Under the Phase Filters
tab, users can manage how to show the related objects. For example, “show
demo+new” filter will show all objects that are demolished and the objects that are in
new construction phase (Fig.7). However, the built-in 4D capability in BIM tools is
for basic project phasing since the phases defined are not based on the “date” and
“time”. For users who need to track a more accurate project schedule such as the
Actual start date, Actual end date, Planned start date, Planned end date, etc., the
direct integration with schedules generated by professional software tools like
Primavera™ is more applicable.
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Figure 7 The phasing function in Revit Architecture 2011
Figure 8 The objects are linked with the defined phases in Revit Architecture 2011
Defined
Phases
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Export 3D BIM to 4D tool and import schedule
The limitations of previous BIM 4D method encouraged the software developers to
find out a way which can fully integrate the scheduling function with the 3D model
(see details of software tools in Table 3). Generally, the steps involves importing the
existing 3D BIM model into the BIM software tool, importing the schedule created by
another scheduling software tool (such as PrimaveraTM and Microsoft Project™) and
then linking the schedule with its relevant objects in the BIM model (Fig.9); some
BIM scheduling software tools may have the in-built function to define the schedule
BIM users can use software tools such as Dprofiler from Beck Technology to generate
the BIM model from paper based drawings. Figure 11 shows a paper-drawing of a
building and its BIM model generated by Dprofiler. The users can first scan the
paper-drawing and then use this scanned sketch to start the building model in
Dprofiler as a starting point. The elevations, floor plans, and site plans in the paper
drawing can also be used to speed up modeling process. Once all the data is captured
in the BIM model, users can generate the QTO from the converted BIM model to
conduct cost estimating of the project.
Figure 11 Generation of BIM model from paper drawing using Dprofiler (Adapted from Dprofiler)
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Chapter 4: A Case Study using BIM
4.1 Introduction
In the previous section, the methods of scheduling and cost estimating in BIM were
introduced. In this chapter, a BIM model of a training facility will be utilized to
illustrate the process of scheduling and cost estimating in BIM. The training facility is
a three-story building in Munich Germany, designed using Autodesk Revit
Architecture™ 2010 (Fig. 12). The building is 19,673.52 sq ft and is equipped mainly
with curtain walls and masonry insulation with seven main rooms and five stairs on
each floor. The first step is to utilize this building model to generate the QTO list
and then level the cost data on the list to estimate the project cost. The second step is
to link the building model with the defined project schedule to simulate the project
process in the 4D environment. The main purpose of the case study is twofold: 1) The
case study will illustrate how BIM technology can work for cost and schedule controls
2) Based on the existing technology, what kind of improvements can be made in the
future.
Figure 12 The training facility model in Munich, Germany
(Source: model provided by Autodesk)
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Problem Statement
BIM as an emerging technology has developed very rapidly in the past decade, and
BIM technology has already started to benefit the designers with intelligent and
model-based design and owners with a more feasible and accessible project.
Contractors, as inter-media between designers and owners, also start to deliver the
project with BIM model. As stated in the previous section, the LOD will be increased
as the project progresses, which means each involved party in the project needs to add
information to the model based on its own preference. From a contractor’s perspective,
two dimensions—time and cost will be added by the contractors after the models are
completed. Since cost and schedule are two key parameters for the construction
management process, it is essential to know if the information in BIM model can help
contractors for the cost and schedule controls and the potential developments can be
made on BIM technology for contractors.
Research Questions
1. Can BIM model be fully utilized by contractors for cost and schedule controls?
2. What kind of improvements can be made from contractor’s perspective for cost
estimating, scheduling and project controls?
Delimitations
The following delimitations define the scope of this study:
1. The purpose of the case study is to illustrate the scheduling and cost estimating
processes with the available BIM model and find out the improvements that can
be made in the future.
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2. This research is limited to performing a quantity takeoff and schedule simulation
since the building model only contains the Shell, Interiors and Services Parts of
the building (Appendix 2).
3. The quantity takeoffs were performed on a building model which has lower LOD
and the total project will be adjusted based on RS Means (2009)(See in Appendix
2).
4. The 4D scheduling and simulation were performed on a building model which has
lower LOD and the schedule is created based on the existing building components,
so the project period developed in the case may not be the accurate period of the
project.
5. The BIM model and software tools used were all adapted from the Autodesk since
Autodesk provides full access of its products to students. The selection of the
software tool may have limitations.
6. The building shown in the model is a training facility in German and the cost
estimation will be adjusted according to “2-4 story office building” category in RS
Means (2009) (See in Appendix 2).
Assumptions
The assumptions of this research included the following:
1. The contractors will have full access to all the selected software tools.
2. The planned and actual dates of schedules are created hypothetically in this case.
3. The building model in the project is drawn correctly with no clashes and errors so
that the measurements and quantities of the objects in the model are reliable.
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Software Tools Selected
The software tools selected in this case study are stated as follows:
1. Autodesk Revit Architecture™ 2011: A BIM-enabled design tool for architects
and designers; Autodesk Revit Architecture™ can capture the design concept and
provide the virtual view of the building design.
2. Autodesk Quantity Takeoff™ 2011: A building cost estimating software for cost
estimators; Autodesk QTO™ can automatically measure areas and count building
components, export to Microsoft Excel, and publish to DWF™ format.
3. Autodesk Navisworks™ 2011: A project review software that supports intelligent
3D model-based designs with scheduling, visualization, and collaboration tools, as
well as advanced clash detection capabilities.
4.2 Cost Estimating
In this case, since the BIM model of the building is available for the quantity take-off,
it is easy to generate the QTO list directly from the building model. As mentioned
before, the BIM model of the building is on a lower LOD. In order to generate a more
accurate project cost, the following steps will be taken:
(1) Export the building model from Revit Architecture™ to Autodesk QTO™:
Transfer the available model to a readable file format for quantity takeoff tool.
(2) Generate the QTO list from the building model.
(3) Export the QTO list to MS Excel™ and map QTO list with RS Means (2009)
cost database.
(4) Adjust the cost according to RS Means (2009) and get the total project cost.
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Step 1: Export the building model from Revit Architecture to QTO tool
Since the Autodesk QTO™ 2011 can only read BIM model in .DWF file format, the
first step is to export the building model from Autodesk™ Revit Architecture 2011
to .DWF file format and then import it into Autodesk™ QTO 2011.Figure 13 shows
the building model is transferred from Autodesk Revit Architecture™ to Autodesk
QTO™ 2011 and the building components are categorized and colored automatically
in Autodesk QTO™. For example, the curtains walls are categorized and colored in
yellow automatically by Autodesk QTO™ (Fig.13).
Figure 13 Export the building model from Revit Architecture into Autodesk™ QTO
Step 2: Generate the QTO list
In the .DWF file, multiple interfaces of the building model can be included, such as
the 3D view, the elevation view, the floor plan views, etc. Autodesk QTO™ 2011 can
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take only minutes to generate the QTO of the entire building and each generated
building components will be colored coded. Figure 14 shows the interface of
Autodesk QTO™ 2011 and three parts are shown: (1) the list of grouped building
components, (2) the 3D view of the building model and (3) the generated QTO list. In
the list of grouped building components, the building components are categorized into
different groups such as doors & windows, walls, ceilings, curtain panel, etc. In the
QTO list, each building component is designated to the same color as shown in the 3D
view. The curtain wall is categorized in the “Curtain Panel” group and colored in
yellow. The quantity of the curtain wall is 23,768.516 sq ft which can be read directly
from the QTO list. The entire process is only finished within 15 minutes and the QTO
process is finished automatically.
Figure 14 The QTO list has been generated by Autodesk™ QTO 2011
QTO List Grouped
Building
Components
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Step 3: Export the QTO list to Excel and calculate the cost
The third step is to export the QTO list to MS Excel™. Since the categories in QTO
list of BIM model is sufficiently clear, users do not need to categorize them manually;
the following work is only to map the cost data such as material cost, labor cost and
equipment cost with the QTO list. In this case, the source of cost data being used is
RS Means (2009). The QTO list in MS Excel™ with the quantity list circled in blue;
the cost data has been added on the list and circled in red (Fig 15). The total estimated
cost of the building is $1,849,766.88
Figure 15 The QTO list shown in Excel with the cost data added
Total Cost
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Step4: Adjust the cost to get the total project cost
The available building model only contains the Shell and Interiors parts of the
building, so the cost estimated in Step 3 cannot be considered as the total project cost
and the adjustments should be made according to RS Means (Appendix 2). Table 7
shows the building components with its percentage of sub-total cost for a 2-4 story
office building (RS Means, 2009). The two colored categories are the components
contained in the building model and it takes 52.3% (12.2% + 15.8% + 1.6% + 22.7%
= 52.3%) of the sub-total cost, so the total sub-total cost is $3,537,030.36. By adding
Contractor fees and Architect Fees, the total Project Cost is $4,668,880.08 and the
cost per square foot is $237.32:
Sub-total cost $3,536,89.16
Contractor Fees (25% of sub-total cost) $884,257.591
Architect Fees(7% of sub-total cost) $247,592.125
Total Project Cost $4,668,880.08
Cost Per sq ft of floor area $237.32/sq ft
Table 7 Model cost calculated for a 2-4 story office building (RS Means, 2009)
Building Components % of Sub-Total A. SUBSTRUCTURE 4.4% B. SHELL B10 Superstructure 12.2% B20 Exterior Enclosure 15.8% B30 Roofing 1.6% C. INTERIORS 22.7% D. Services D10 Conveying 8.9% D20 Plumbing 2.8% D30 HVAC 11.8% D40 Fire Protection 2.8% D50 Electrical 17.0% E. EQUIPMENT & FURNISHINGS 0.0% F. SPECIAL CONSTRUCTION 0.0% G. BUILDING SITEWORK NA
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4.3 Construction Scheduling
By using the same .DWF model, Autodesk Navisworks™2011 can simulate the
schedule of the project by adding the fourth dimension—time into the model. The
time frame we set up for this case is starting at Mar. 21st 2011 and the project would
approximately last 7 months and completing by Oct. 31st. As stated in Chapter 3, there
are two different ways to add/incorporate the schedule into the building model: (1)
Importing Primavera or MS Project schedule or (2) defining the tasks in the Autodesk
Navisworks directly. For this case study, the second approach was used; the tasks
were defined directly in the Autodesk Navisworks™ 2011 and the steps are stated as
follows:
(1) Define the tasks in Autodesk Navisworks™ 2011
(2) Get the Gantt View of the project schedule
(3) 4D simulation view
Step 1: Defining Tasks
Autodesk Navisworks™ 2011 allows users to define tasks directly in the software tool
itself and then link building components with these defined tasks. In Figure 16, under
the “Tasks” tab, each task is defined with Start date and End date, Planned Start date
and Planned End date. The limitation is that the precedence relationships between
tasks cannot be defined in the Autodesk Navisworks™. The Start date and End date
show the actual project start and end dates and the scheduled dates are shown under
“Planned Start” and “Planned End”. Each task also has its own Status identified by an
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icon, representing planned against actual relationships. Each icon shows two bars: the
top bar represents the Planned dates and the bottom bar represents the Actual dates. If
the Actual start and finish dates are the same as the Planned start and finish dates, the
bars are displayed in green. Any variations between Planned and Actual dates are
displayed in red. Missing Planned or Actual dates are shown in grey. The interface can
clearly show to the Contractor and the Owner the updated status of the project. In this
case study, 25 tasks are defined based on the available building model and as the
building design has changed, the tasks can be changed accordingly.
Figure 16 Tasks are defined directly in Autodesk™ Navisworks 2011
Step 2: Gantt View
Under the Gantt View tab, a Gantt chart view provides a graphical representation of
the project schedule based on the tasks defined in Step 1. In Figure 17, the tasks are
shown in multi-column table on the left and colored Gantt bars are shown on the right.
Each task takes up one row. Planned, Actual, and Planned vs. Actual Gantt charts can
be selected based on the users’ preference. In Figure 18, the bars of Actual and
Planned Gantt charts are shown as blue; in the Planned vs. Actual Gantt chart view,
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the planned dates are shown as grey bars and the actual dates are shown as red bars
(Note: the color of the red and grey bars are not representing the status of the project).
Figure 17 Tasks are shown in Gantt View
Figure 18 Three Gantt Chart views can be selected based on the user’s preference
Actual vs. Planned
Planned
Actual
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Step 3 4D Simulation
The third step is to simulate the project phases in the 4D environment. In step 1, the
tasks defined are linked to the relevant building components in the Autodesk
Navisworks™ 2011. Under the “simulate” tab, the tasks are simulated. In Figure 19,
the simulation of the project progress is shown on 12 weekly based interfaces. On the
upper left side of simulation interfaces, the date, on-going project sequence and its
finished percentage are shown. By showing project phases and site logistics in a
virtual environment, 4D simulation in BIM dynamically provides users with different
project statuses. It is also convenient for the project contractor to provide the owner
with a virtual and intuitive view of the project progress. The contractor, the owner and
even the designers can be on the same page at any time to share understanding of
project status, milestones, responsibilities, and construction plans. If the contractor
defines a date under the simulation tab, the simulation interface can also show the
on-going tasks with the percentage of finished tasks on the defined date. The 4D
simulation in BIM provides the contractor with a virtual view of the project status.
Moreover, it helps the contractor to adjust the project schedule according to any
design change since the simulated tasks are linked to building components of the
building model.
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Figure 19 The interfaces of Autodesk Navisworks™ of 4D Scheduling in BIM
Week 1 Week 3 Week 4
Week 7 Week 10 Week 13
Week 16 Week 17 Week 20
Week 22 Week 23 Week 25
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4.3 Conclusions
A careful review of the case study shows that BIM technology brings many advanced
construction management skills to cost estimating, project scheduling and even
project controls for contractors.
In this case study, the QTO process is automatic and reliable, which is finished within
15 minutes, since the quantities of the building components are “read” by Autodesk
QTO™ 2011 from the building model directly. This will save contractors substantial
amount of time on cost estimating. On the other hand, the change of the design in the
building model can be updated and reflected in the QTO list in minutes, which means
that the owner (and in case of contracts where contractors are part of the team during
design phase, contractors) can get a faster cost feedback on changes in design using
BIM technology.
The 4D BIM links the building components with tasks and simulate these tasks in the
4D environment—the design and the construction schedule are synchronized. In this
case study, the tasks defined with planned and actual dates are represented in Gantt
chart view. By comparing the planned and actual dates, the status bars can tell the
contractor the progress of the project in an intuitive and simple way. The simulation of
the progress can also help contractor to adjust the project schedule according to the
design change in building model.
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Chapter 5: Conclusions and Future Work
5.1 Conclusions
Building Information Modeling (BIM) is an emerging technology in AEC industry. It
provides users with more accurate and consistent project information throughout the
lifecycle. In this thesis, diverse BIM tools and BIM application areas have been
discussed with emphasis on scheduling and cost estimating. Two approaches for 4D
scheduling in BIM have been presented: i) BIM tools with 4D capacity ii) use of 4D
BIM tool to link the 3D BIM model with the project schedule. After that, three types
of cost estimation methods have been discussed: i) export the QTO list from the BIM
tool to the estimating software such as MS Excel ii) link BIM components to
estimating software iii) use QTO tool to extract the QTO list from the model. Based
on the available methods, a case study is presented to illustrate the scheduling and
cost estimating processes in BIM based on the BIM model of a 3-story training
facility. The case study shows the QTO process can be finished in a more automatic
and reliable way and the 4D scheduling function in BIM simulate the project schedule
in the 4D environment. Based on the literature review and the case study, some
developments might be foreseen in the future.
5.2 Future Work
Contractors are “responsible for providing all of the material, labor, equipment,
(engineering vehicles and tools) and services necessary for the construction of the