1. Introduction Every construction project is unique and has its own operating environment and
sets of technical requirements. As a result, the execution of a construction project is subject to
numerous constraints that limit the commencement or progression of field operations, which
invariably have significant negative impact on overall project performance. By definition,
constraints refer to any condition, such as temporal/spatial limitations and safety/quality
concerns, which may prevent a project to achieve its goals. Successful execution and control of
a construction project relies on effective identification and management of constraints through
master planning and short-term look-ahead scheduling. While the master schedule provides a
global view of a project and the overall execution strategy, a look-ahead schedule offers a detail
account of operational constraints and a detailed plan showing work to be done within a
relatively short time window. Ideally, these detailed schedules should reflect actual field
conditions and provide field personnel with operation instructions free of constraints and
conflicts (Hinze 2008). This look-ahead scheduling and constraint analysis procedure is also a
critical component of the last-planner methodology proposed by Ballard (2000). This research
project will provide an overview of state-of-art schedule constraint analysis practice during look-
ahead scheduling. In addition, it will propose a conceptual framework for managing constraints.
Background or introduction section provides a description of the basic facts and importance of
the research area - What is your research area, the motivation of research, and how important
is it for the industry practice/knowledge advancement? 2. Problem Statement The importance of
developing a constraint-free and reliable work plan has long been recognized by the industry.
However, numerous construction projects are still plagued by delays and cost overruns, which
can frequently be traced to ineffective identification and treatment of constraints. First, when a
constraint is not properly identified during scheduling, subsequent conflicts in the field are
inevitable. Today’s projects are becoming more and more technically complex and logistically
challenging, which exposes construction operations to even more complex constraints. Second,
the traditional scheduling methods, bar charts and Critical Path Method (CPM) which are widely
used as a basis for constraint analysis, greatly limit our capability in modeling and resolving
constraints. 2. Problem Statement The importance of developing a constraint-free and reliable
work plan has long been recognized by the industry. However, numerous construction projects
are still plagued by delays and cost overruns, which can frequently be traced to ineffective
identification and treatment of constraints. First, when a constraint is not properly identified
during scheduling, subsequent conflicts in the field are inevitable. Today’s projects are
becoming more and more technically complex and logistically challenging, which exposes
construction operations to even more complex constraints. Second, the traditional scheduling
methods, bar charts and Critical Path Method (CPM) which are widely used as a basis for
constraint analysis, greatly limit our capability in modeling and resolving constraints More
specifically, the following research questions need to be addressed. The result of this study will
be valuable to the industry practitioners as well as related software providers in developing
better practice and tools for constraint management and look-ahead scheduling.
2 The long term goal of the research is to develop a formalized constraint management system.
Constraint management is defined herein as the process of identifying, classifying, modeling,
, and resolving constraints. The objective of the current study is to provide a comprehensive
review of literatures and industry practices in relation to constraint analysis and outline a
conceptual framework for constraint management. Particularly, the study has the following sub-
objectives: 1. To provide a comprehensive review of sources and characteristics of constraints
typically found in construction projects; 2. To develop a constraint classification method for
easier constraint identification and modeling; 3. To review current industry practices and
researches in regards to constraint modeling; 4. To outline a conceptual framework for total
constraint management.1. What are the typical constraints found in various construction
projects? 2. How to classify these constrains for easier identification and modeling? 3. What are
the current industry practice as well as research advancements in modeling and resolving
constraints? How to unify the constraint classification knowledge and various constraint
modeling efforts into a framework for total constraint management?The result of this study will
be valuable to the industry practitioners as well as related software providers in developing
better practice and tools for constraint management and look-ahead scheduling.The primary
research method for this study is literature review and conceptual modeling. Constraint
identification and classification through a structured approach is the very first step toward a
“zero-constraint” environment. This study will first review various types of constraints in
construction and their characteristics. Based on this understanding, a classification method will
be developed to categorize constraint factors for the purpose of constraint identification and
modeling. In the second stage of this study, existing constraint modeling methods will be
identified based on a comprehensive review of current industry practices and academic
researches. Finally, once the constraint classification and modeling techniques are identified, a
conceptual framework for total constraint management will be outlined. This study will be
conducted bet ween September 2010 and May 2011.
A preliminary literature review shows that past studies are primarily focused on understanding
and modeling a particular type of constraint, such as technological, contractual, resource,
spatial, and information constraints. Limited progress has been made on classifying various
constraints according to their characteristics in a comprehensive manner. In terms of modeling
and resolving constraints, various approaches have been recommended. For example, many
CPM-based methods are applied to deal with time-related constraints; knowledge-based
systems were used to automate work plan generation; network-based optimization algorithms
were developed to resolve constraints; and databases and visualization techniques, such as 3D,
4D, and Virtual Reality (VR), are used to communicate and visualize constraints. What is
missing from the past studies is a comprehensive and structured approach in managing
constraints. Since the 1960s, concern that American students may not be capable of
transferring the skills they have gained from their education to the practical problems of life has
troubled educators. Of greatest concern is whether students have mastered “critical thinking” or
“higher order thinking skills” and can apply them outside of school curricula. These concerns
have given rise to the “critical thinking movement.” To demonstrate that the movement is
successful, it must prove that its efforts not only increase the critical thinking of students in
school, but that students can transfer critical thinking to novel situations, including those
encountered in daily life. The primary purpose of this review is to ascertain if there is compelling
evidence that efforts to teach critical thinking have had this result. What became apparent in the
sets of technical requirements. As a result, the execution of a construction project is subject to
numerous constraints that limit the commencement or progression of field operations, which
invariably have significant negative impact on overall project performance. By definition,
constraints refer to any condition, such as temporal/spatial limitations and safety/quality
concerns, which may prevent a project to achieve its goals. Successful execution and control of
a construction project relies on effective identification and management of constraints through
master planning and short-term look-ahead scheduling. While the master schedule provides a
global view of a project and the overall execution strategy, a look-ahead schedule offers a detail
account of operational constraints and a detailed plan showing work to be done within a
relatively short time window. Ideally, these detailed schedules should reflect actual field
conditions and provide field personnel with operation instructions free of constraints and
conflicts (Hinze 2008). This look-ahead scheduling and constraint analysis procedure is also a
critical component of the last-planner methodology proposed by Ballard (2000). This research
project will provide an overview of state-of-art schedule constraint analysis practice during look-
ahead scheduling. In addition, it will propose a conceptual framework for managing constraints.
Background or introduction section provides a description of the basic facts and importance of
the research area - What is your research area, the motivation of research, and how important
is it for the industry practice/knowledge advancement? 2. Problem Statement The importance of
developing a constraint-free and reliable work plan has long been recognized by the industry.
However, numerous construction projects are still plagued by delays and cost overruns, which
can frequently be traced to ineffective identification and treatment of constraints. First, when a
constraint is not properly identified during scheduling, subsequent conflicts in the field are
inevitable. Today’s projects are becoming more and more technically complex and logistically
challenging, which exposes construction operations to even more complex constraints. Second,
the traditional scheduling methods, bar charts and Critical Path Method (CPM) which are widely
used as a basis for constraint analysis, greatly limit our capability in modeling and resolving
constraints. 2. Problem Statement The importance of developing a constraint-free and reliable
work plan has long been recognized by the industry. However, numerous construction projects
are still plagued by delays and cost overruns, which can frequently be traced to ineffective
identification and treatment of constraints. First, when a constraint is not properly identified
during scheduling, subsequent conflicts in the field are inevitable. Today’s projects are
becoming more and more technically complex and logistically challenging, which exposes
construction operations to even more complex constraints. Second, the traditional scheduling
methods, bar charts and Critical Path Method (CPM) which are widely used as a basis for
constraint analysis, greatly limit our capability in modeling and resolving constraints More
specifically, the following research questions need to be addressed. The result of this study will
be valuable to the industry practitioners as well as related software providers in developing
better practice and tools for constraint management and look-ahead scheduling.
2 The long term goal of the research is to develop a formalized constraint management system.
Constraint management is defined herein as the process of identifying, classifying, modeling,
, and resolving constraints. The objective of the current study is to provide a comprehensive
review of literatures and industry practices in relation to constraint analysis and outline a
conceptual framework for constraint management. Particularly, the study has the following sub-
objectives: 1. To provide a comprehensive review of sources and characteristics of constraints
typically found in construction projects; 2. To develop a constraint classification method for
easier constraint identification and modeling; 3. To review current industry practices and
researches in regards to constraint modeling; 4. To outline a conceptual framework for total
constraint management.1. What are the typical constraints found in various construction
projects? 2. How to classify these constrains for easier identification and modeling? 3. What are
the current industry practice as well as research advancements in modeling and resolving
constraints? How to unify the constraint classification knowledge and various constraint
modeling efforts into a framework for total constraint management?The result of this study will
be valuable to the industry practitioners as well as related software providers in developing
better practice and tools for constraint management and look-ahead scheduling.The primary
research method for this study is literature review and conceptual modeling. Constraint
identification and classification through a structured approach is the very first step toward a
“zero-constraint” environment. This study will first review various types of constraints in
construction and their characteristics. Based on this understanding, a classification method will
be developed to categorize constraint factors for the purpose of constraint identification and
modeling. In the second stage of this study, existing constraint modeling methods will be
identified based on a comprehensive review of current industry practices and academic
researches. Finally, once the constraint classification and modeling techniques are identified, a
conceptual framework for total constraint management will be outlined. This study will be
conducted bet ween September 2010 and May 2011.
A preliminary literature review shows that past studies are primarily focused on understanding
and modeling a particular type of constraint, such as technological, contractual, resource,
spatial, and information constraints. Limited progress has been made on classifying various
constraints according to their characteristics in a comprehensive manner. In terms of modeling
and resolving constraints, various approaches have been recommended. For example, many
CPM-based methods are applied to deal with time-related constraints; knowledge-based
systems were used to automate work plan generation; network-based optimization algorithms
were developed to resolve constraints; and databases and visualization techniques, such as 3D,
4D, and Virtual Reality (VR), are used to communicate and visualize constraints. What is
missing from the past studies is a comprehensive and structured approach in managing
constraints. Since the 1960s, concern that American students may not be capable of
transferring the skills they have gained from their education to the practical problems of life has
troubled educators. Of greatest concern is whether students have mastered “critical thinking” or
“higher order thinking skills” and can apply them outside of school curricula. These concerns
have given rise to the “critical thinking movement.” To demonstrate that the movement is
successful, it must prove that its efforts not only increase the critical thinking of students in
school, but that students can transfer critical thinking to novel situations, including those
encountered in daily life. The primary purpose of this review is to ascertain if there is compelling
evidence that efforts to teach critical thinking have had this result. What became apparent in the
