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This paper further develops the models proposed by prior research in the field of workspace conflict using four- dimensional computer-aided design. The approach developed here analyzes spatial demand and supply from the perspective of construction operators, and a modeling methodology based on spatiotemporal utilization is proposed. The utilization factor model is developed to show that the criticality of the operator's spatiotemporal demand leads to worksite congestion and that congestion is a form of worksite conflict. The interference of other space entities increases the space demand, and this increment is quantified with a 'dynamic space interference' index This indicator is developed to identify activity spaces which suffer congestion. A decision making tool, the 'congestion penalty indicator,' is developed which obtains a schedule-level value for analysis, evaluation, and comparison. Finally, a case study on the refurbishment of an oil refinery column is used to demonstrate the application of the above concepts in successfully identifying a better schedule with respect to on-site congestion. DOI: 10.1061/(ASCE)CO.1943-7862.0000166 CE Database subject headings: Construction management; Spatial analysis; Construction sites; Workspace; Models. Author keywords: 4D CAD; Construction management; Spatial analysis; Temporal analysis; Site congestion; Workspace.

There are temporal relationships other than the precedence ones between construction activities. Many of these relationships are related to the perspective of intermediate function requirement. The construction industry still lacks a representation schema for capturing the temporal logics residing in this kind of construction requirement. This study presents a schema for representing these temporal logics from three perspectives, namely the construction life cycle of a single product component, the functional interdependencies between two in-progress components, and the availability conditions of an intermediate functionality. In this way, the concurrency relationships among the construction processes can be identified and evaluated, and the intermediate function analysis can be conducted more efficiently, thus contributing to improvement of the executability of construction schedules. Additionally, the temporal logics have been formulated in the format based on temporal interval algebra, which provides a richer semantic representation compared to the traditional precedence relationship types. Finally, using a four-dimensional simulation prototype, a case study of constructing the deck of a bridge by the balanced cantilever approach is modeled to demonstrate the representation of the three perspectives of intermediate function requirements. DOI:10.1061/(ASCE)0733-9364(2007)133:4(277) CE Database subject headings: Constructability; Construction methods; Scheduling; Construction management.

Evaluating construction requirements should be an indispensable part of improving the constructability of a facility project. However, a number of existing function analysis approaches focus mainly on the final functions with respect to the finished facility. The construction industry still lacks methodologies to represent and evaluate the functional construction requirements for constructability analysis. This paper develops the concept of intermediate functions for representing the construction requirements from three perspectives, namely, function user, function provider, and the temporal and spatial relationships between the user and the provider. This is followed by the development of an in-progress product model to abstract the construction lifecycle of a facility product utilizing the concept of component state. Furthermore, the reference relationships among such perspectives as in-progress product, intermediate function, resource, and process are addressed. Based on these reference relationships, the bottleneck states for providing the intermediate functions can be detected. A case study of constructing the deck of a bridge using the balanced cantilever approach is presented to illustrate the utilization of this concept and representation. CE Database subject headings: Constructability; Construction management; Models; Evaluation.

Many researchers agree that smoother construction would result from better communication between designers and constructors about specific requirements and constraints for construction that can be incorporated into the design. The same principle can be generalized to apply to all the phases of a construction project (design, equipment procurement, transport, delivery, installation, and testing, as well as hand-over activities), to the different partners (main contractors, subcontractors, and suppliers), and even internally to the teams working on different parts of a system for the same contractor. Specific requirements and constraints at work interfaces that are technical, organizational, temporal, and geographical in nature have to be made transparent so that they can be managed and resolved to avoid unnecessary reworks and delays. This paper proposes to use the work breakdown structure (WBS) concept to improve work interface management. In the manufacturing industry, the WBS concept is well exploited by crossing a horizontal breakdown of production activities with a vertical breakdown of final products, thus obtaining a WBS matrix, which is more complete and useful than the classical WBS tree. In this paper, the WBS and interface management concepts are first clarified. Then, it is proposed to transpose the WBS matrix concept into the construction industry and to analyze, in a case study, how it may be used to improve interface management. The case study involves the construction of a segment of a mass rapid transit system comprising many specialty trades spanning track works, power supply, signaling, passenger vehicles, and control. DOI: 10.1061/(ASCE)0733-9364(2006)132:1(67) CE Database subject headings: Project management; Internet; Construction management; Communication.

Stringent pressure on public finances has made China's infrastructure development a 'bottleneck' in its bid to sustain rapid economic growth. As a result, many modalities have been developed to utilize the resources and skills of the private sector to supply essential infrastructure products and services, as well as to improve the efficiency in government procurement of the same. The build--operate--transfer (BOT) approach is an important example of these innovative modalities. The BOT approach in China is still in its infancy; many pitfalls await the unwary and obstacles impede more extensive application of this modality. The pitfalls are attributable to the complexities in the BOT approach, particularly when attempted in China's transition economy emerging from decades of central planning to become one that is more market driven and globally integrated. This paper proposes two systems concepts to help manage this complexity: (1) a process modeling approach that maps key functions, parameters and interfaces in the project delivery process, and (2) the use of interface management involving specific measures that have contributed towards project success in Chinese BOT projects. The process modeling approach has led to the development of China's BOT genetic process model (CBGPM). Expert opinion was elicited on the criticality of the interfaces identified in CBGPM as well as the effectiveness of selected interface management measures. Finally, an interface management framework consisting of five key steps is suggested for China's BOT projects. DOI: 10.1061/(ASCE)0733-9364(2005)131:6(645) CE Database subject headings: Infrastructure; Build/Operate/Transfer; Interfaces; Project management; China.

A new approach for resource scheduling using genetic algorithms (GAs) is presented here. The methodology does not depend on any set of heuristic rules. Instead, its strength lies in the selection and recombination tasks of the GA to learn the domain of the specific project network. By this it is able to evolve improved schedules with respect to the objective function. Further, the model is general enough to encompass both resource leveling and limited resource allocation problems unlike existing methods, which are class-dependent. In this paper, the design and mechanisms of the model are described. Case studies with standard test problems are presented to demonstrate the performance of the GA-scheduler when compared against heuristic methods under various resource availability profiles. Results obtained with the proposed model do not indicate an exponential growth in the computational time required for larger problems.

A framework for a pavement-management system is presented, which employs mechanistic performance submodels to predict pavement behavior. These performance submodels predict the development of pavement distresses in terms of traffic loading and pavement structure. This approach enables the effectiveness of pavement rehabilitation strategies to be evaluated with respect to individual distress modes. It also forms the basis for a dynamic programming optimization scheme, which considers life-cycle costs for budget allocation. The performance submodels are formulated within a probabilistic framework to incorporate uncertainty information on the factors governing pavement deterioration. The transition probabilities from one pavement state to another for a set of rehabilitation alternatives are determined using the first-order reliability method (FORM). The methodology allows multiple distress mode condition to be considered using the concept of cut sets. These probabilities serve as inputs to the optimization submodel, which determines the optimal rehabilitation strategy in terms of discounted life-cycle costs subjected to management and operational constraints.