@article{bonilla_rasdorf_liu_al-ghandour_he_2023, title={Inequity Reduction in Road Maintenance Funding for Municipalities}, volume={28}, ISSN={["1552-7549"]}, url={https://doi.org/10.1177/1087724X221130047}, DOI={10.1177/1087724X221130047}, abstractNote={ State transportation agencies distribute funding to eligible municipalities to maintain local roads in a safe condition based on their permanent population and street mileage. However, some municipalities experience an exceedingly high seasonal population that is unaccounted for and thus, they are not receiving equitable funding. To better understand seasonal population and mitigate its impact, this paper evaluates equity and affordability in funding allocation, explores how to estimate seasonal population, suggests a method to improve the current allocation, and identifies practical strategies to reduce disproportionate funding distribution. Three funding allocation strategies were developed and a need-based funding allocation approach was identified to be an equitable solution to help municipalities improve local street conditions based on their needs while subject to constraints on funding availability. This approach allows municipalities to address seasonal population increases without negatively impacting funds for municipalities that do not experience fluctuations in their population. }, number={3}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Bonilla, Minerva and Rasdorf, William and Liu, Min and Al-Ghandour, Majed and He, Chuanni}, year={2023}, month={Jul}, pages={339–362} }
 @article{chen_liu_li_hsiang_jarvamard_2023, title={Motivating Reliable Collaboration for Modular Construction: Shapley Value-Based Smart Contract}, volume={39}, ISSN={["1943-5479"]}, url={https://doi.org/10.1061/JMENEA.MEENG-5428}, DOI={10.1061/JMENEA.MEENG-5428}, abstractNote={Establishing a fair benefit distribution system for construction projects, in which participants often need to work together in a highly uncertain and interrelated environment, is challenging. There is a lack of objective mechanism for construction projects to motivate reliable workflow automatically and instantly. The objective of this study is to develop Shapley value–based smart contracts to automatically assign fair rewards/penalties to motivate task-level collaborations. The research first developed a simulation model to quantify subcontractors’ marginal contributions under different coalitional scenarios. Then, the simulation results were aggregated using Shapley value to determine each participant’s reasonable rewards/penalties. Lastly, the payment was encoded in the smart contract and then deployed in the blockchain to self-enforce consensus executions. The results showed that Shapley value–based smart contracts exhibited incentives to motivate reliable contributions and enable peer negotiations to realize task-level production. The contributions of this study to the body of knowledge are (1) quantify subcontractors’ marginal contributions to the project, and (2) determine how to distribute fair collaborative outcomes when project participants can perform at different levels of effort. The incentives embedded in smart contracts can reshape project participants’ collaborative behaviors toward desired outcomes, enabling a self-manage, self-govern, and self-adjust decentralized autonomous organization.}, number={6}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Chen, Gongfan and Liu, Min and Li, Huaming and Hsiang, Simon M. and Jarvamard, Ashtad}, year={2023}, month={Nov} }
 @article{he_liu_zhang_wang_hsiang_chen_li_dai_2023, title={Space-Time-Workforce Visualization and Conditional Capacity Synthesis in Uncertainty}, volume={39}, ISSN={["1943-5479"]}, url={https://doi.org/10.1061/JMENEA.MEENG-4991}, DOI={10.1061/JMENEA.MEENG-4991}, abstractNote={Workspace, project duration, and workforce are three critical resources for construction projects. Project managers need to expend time and effort reviewing, comprehending, and coordinating these resources. However, the space–time–workforce interactions and their impact on decision-making in project scheduling are not fully known. Therefore, the objectives of this research were to understand the impact of workforce shifts on space, time, and labor cost performances, develop a three-dimensional (3D) visualization tool to reveal activity-level resource dynamics, and associate the risk aftermath with the occurrence probability to balance subjective risk tolerance and objective system reliability. This research developed a simulation model based on a case project to compare the workflow of five major specialty trades (i.e., bar placer, carpenter, scaffolder, pipefitter, and concreter) in 267 scenarios. A resource-oriented 3D visualization tool was developed to help project managers monitor project schedules. The research established a risk control framework using value-at-risk (VaR) and conditional value-at-risk (CVaR) approaches to associate extreme outcomes with their occurrence probability. Simulation results indicated that pipefitters significantly affected workspace overlap, whereas bar placers and carpenters predominantly impacted project duration. The scholarly contributions are (1) the creation of an intelligent system to generate a project schedule from workforce assignments specified by project managers, (2) development of a tool to visualize the three-way resource dynamics of workforce, time, and space on a 3D model for all possible scenarios, and (3) development of a framework for project managers to balance planning strategies between subjective risk tolerance and objective system reliability. This research provides project managers with a dynamic 3D visualization of space, time, and workforce utilization and interaction in uncertain environments, further facilitating reliable project scheduling decision-making.}, number={2}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={He, Chuanni and Liu, Min and Zhang, Yuxiang and Wang, Zhigao and Hsiang, Simon M. M. and Chen, Gongfan and Li, Weiqiang and Dai, Gongfu}, year={2023}, month={Mar} }
 @article{bonilla_rasdorf_liu_al-ghandour_he_2022, title={Inequity Reduction in Road Maintenance Funding for Municipalities}, volume={9}, ISSN={["1552-7549"]}, DOI={10.1177/I087724X221130047}, journal={PUBLIC WORKS MANAGEMENT & POLICY}, author={Bonilla, Minerva and Rasdorf, William and Liu, Min and Al-Ghandour, Majed and He, Chuanni}, year={2022}, month={Sep} }
 @article{liu_jarvamardi_zhang_liu_hsiang_yang_yu_jiang_2021, title={Comparative Study on Perception of Causes for Construction Task Delay in China and the United States}, volume={147}, ISSN={["1943-7862"]}, DOI={10.1061/(ASCE)CO.1943-7862.0001985}, abstractNote={AbstractRapidly growing construction markets in China and the United States have provided opportunities for contractors to venture into foreign industries. To help project managers understand the f...}, number={3}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Liu, YanChun and Jarvamardi, Ashtad and Zhang, YuXiang and Liu, Min and Hsiang, Simon M. and Yang, ShuJuan and Yu, XiuXia and Jiang, ZhiHao}, year={2021}, month={Mar} }
 @article{mccoy_bourara_lucier_seracino_liu_lin_2021, title={Prestressed MF-FRP: Experimental Study of Rapid Retrofit Solution for Deteriorated Prestressed C-Channel Beams}, volume={35}, ISSN={["1943-5509"]}, url={https://doi.org/10.1061/(ASCE)CF.1943-5509.0001536}, DOI={10.1061/(ASCE)CF.1943-5509.0001536}, abstractNote={AbstractThis paper presents design and installation details and full-scale test results for a prestressed mechanically fastened fiber-reinforced polymer (MF-FRP) retrofit solution that restores the...}, number={1}, journal={JOURNAL OF PERFORMANCE OF CONSTRUCTED FACILITIES}, author={McCoy, Brad C. and Bourara, Zakariya and Lucier, Gregory W. and Seracino, Rudolf and Liu, Min and Lin, Sheng-Hsuan}, year={2021}, month={Feb} }
 @article{zhang_javanmardi_liu_yang_yu_hsiang_jiang_liu_2020, title={How Does Experience with Delay Shape Managers' Making-Do Decision: Random Forest Approach}, volume={36}, ISSN={["1943-5479"]}, DOI={10.1061/(ASCE)ME.1943-5479.0000776}, abstractNote={AbstractMaking-do, a decision to start a construction task despite knowing that its preconditions are not fully ready, is a complex dilemma for construction managers. Managers’ previous making-do d...}, number={4}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Zhang, YuXiang and Javanmardi, Ashtad and Liu, YanChun and Yang, ShuJuan and Yu, XiuXia and Hsiang, Simon M. and Jiang, ZhiHao and Liu, Min}, year={2020}, month={Jul} }
 @article{javanmardi_abbasian-hosseini_liu_hsiang_2020, title={Improving Effectiveness of Constraints Removal in Construction Planning Meetings: Information-Theoretic Approach}, volume={146}, ISSN={["1943-7862"]}, DOI={10.1061/(ASCE)CO.1943-7862.0001790}, abstractNote={AbstractTimely identification and removal of constraints is critical for improving workflow reliability. Construction project managers need to spend a significant amount of working time in various ...}, number={4}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Javanmardi, Ashtad and Abbasian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2020}, month={Apr} }
 @article{alves_liu_scala_javanmardi_2020, title={Schedules and Schedulers: A Study in the US Construction Industry}, volume={32}, ISSN={["2377-0643"]}, DOI={10.1080/10429247.2020.1738878}, abstractNote={This research examines how the construction industry addresses the roles of schedulers and schedules, with the goal of improving current practices. We use a mixed-mode approach of qualitative and q...}, number={3}, journal={ENGINEERING MANAGEMENT JOURNAL}, author={Alves, Thais da C. L. and Liu, Min and Scala, Natalie M. and Javanmardi, Ashtad}, year={2020}, month={Jul}, pages={166–185} }
 @article{olivieri_seppanen_alves_scala_schiavone_liu_granja_2019, title={Survey Comparing Critical Path Method, Last Planner System, and Location-Based Techniques}, volume={145}, ISSN={["1943-7862"]}, DOI={10.1061/(ASCE)CO.1943-7862.0001644}, abstractNote={AbstractIn construction, the most relevant systems used for project management (PM) and project production management (PPM) in the planning and control phases are critical path method (CPM), last p...}, number={12}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Olivieri, Hylton and Seppanen, Olli and Alves, Thais da C. L. and Scala, Natalie M. and Schiavone, Vincent and Liu, Min and Granja, Ariovaldo Denis}, year={2019}, month={Dec} }
 @article{javanmardi_abbasian-hosseini_liu_hsiang_2018, title={Benefit of Cooperation among Subcontractors in Performing High-Reliable Planning}, volume={34}, ISSN={["1943-5479"]}, DOI={10.1061/(asce)me.1943-5479.0000578}, abstractNote={As construction projects get larger and more complex, subcontractors can benefit from cooperation and by forming an alliance, such as partnering. Previous studies have discussed the benefit of cooperation or partnering among subcontractors and between them and other project stakeholders. However, there has been limited research to quantify the benefit of cooperation among subcontractors in performing high-reliable planning (HRP). Therefore, the purpose of this paper is to quantify the benefit of cooperation among subcontractors in increasing their planning reliability at an operational level. Although HRP reduces the variability in a production system that significantly benefits the downstream subcontractors, it requires every subcontractor to put more time, cost, and effort into the planning stage, which may not be cost-effective for upstream subcontractors. To model the described situation, a simulation model (built by simulation software) was integrated with a cost model that identifies the relationship between cost and work-plan reliability (WPR) level. By utilizing different benefit-allocation models and evaluating their solutions, the paper demonstrates that a contribution-based benefit-allocation (CBBA) model using a game theory framework can provide the most acceptable and incentivizing solutions for the benefit-allocation problem. This study contributes to the body of knowledge in lean construction by quantifying the benefit of subcontractors’ cooperation in increasing their planning reliability.}, number={2}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Javanmardi, Ashtad and Abbasian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2018}, month={Mar} }
 @inproceedings{javanmardi_hsiang_liu_2018, title={Effects of General Contractor’s Loading Strategies on Project and Trades’ Performance}, ISBN={9780784481271}, url={http://dx.doi.org/10.1061/9780784481271.044}, DOI={10.1061/9780784481271.044}, abstractNote={General contractor’s (GC) loading strategies, defined as the amount of work GC assigns to trades in a given time, directly impact project and trades’ performance. Previous researchers have discussed that it is beneficial not to load 100% of trades production capacity and account for variability in the flow of work passing from one trade to another. However, there has been limited research identifying to what extent underloading is beneficial for both trades and the project. By modifying the Parade Game model and considering different levels of workflow variability, this paper quantifies the effects of GC’s loading strategies on project cycle time and trades’ utilization. This study simulates a single-line production system in which GC controls the rate of work assigned to the production system. Results show that: (1) although underloading will result in shorter cycle times, 40% underloading could lower trades’ average utilization up to 34%; and (2) in a variable production system with a coefficient of variation (CV) of 0.71, variability should be reduced 1.625 times more to achieve a short cycle time of 6 weeks but 14% more trades’ average utilization, considering 70% trades’ average utilization as a benchmark. The findings of this paper will be useful to project managers by enabling them to develop production strategies that lead to better project cycle time and trades’ utilization.}, booktitle={Construction Research Congress 2018}, publisher={American Society of Civil Engineers}, author={Javanmardi, Ashtad and Hsiang, Simon M. and Liu, Min}, year={2018}, month={Mar} }
 @article{abbasian-hosseini_liu_howell_2018, title={Investigating the Cost-Benefit Trade-Off of Additional Planning Using Parade Game Simulation}, volume={34}, ISSN={["1943-5479"]}, DOI={10.1061/(asce)me.1943-5479.0000580}, number={2}, journal={JOURNAL OF MANAGEMENT IN ENGINEERING}, author={Abbasian-Hosseini, S. Alireza and Liu, Min and Howell, Gregery}, year={2018}, month={Mar} }
 @article{abbsaian-hosseini_liu_hsiang_2017, title={Social network analysis for construction crews}, volume={19}, ISSN={1562-3599 2331-2327}, url={http://dx.doi.org/10.1080/15623599.2017.1389642}, DOI={10.1080/15623599.2017.1389642}, abstractNote={ABSTRACT Construction crews usually have to share the limited working space with each other during construction to perform their tasks, which increases the chance of interference/conflict and productivity lost. Social network analysis (SNA) has been known as a methodology to determine the conditions of social structures by investigating the interdependencies among a set of actors. The impact of jobsite social network on the performance of the crews has not been well documented in previous research. This research proposes an analytical approach by combining SNA and work plan variation analysis to (1) quantify the influence construction crews receive from jobsite social network, and (2) explore the impact of jobsite social network on the crews’ performance particularly on their work plan variation through a case study. The results indicated that there is a positive monotonic association between each of the centrality indices (representing network influence on each crew) and each of the work plan variability indices (representing crew's performance). The more influences a crew receives form the network, the more work plan variation it will have. A better understanding of the existing jobsite interdependencies will help project managers to control it through better planning and leadership, consequently increasing jobsite productivity.}, number={2}, journal={International Journal of Construction Management}, publisher={Informa UK Limited}, author={Abbsaian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2017}, month={Nov}, pages={113–127} }
 @article{abbasian-hosseini_liu_hsiang_2017, title={Social network conformity and construction work plan reliability}, volume={78}, ISSN={["1872-7891"]}, DOI={10.1016/j.autcon.2017.01.004}, abstractNote={In a large construction project delivery is usually handled by numerous subcontractors. Work plan reliability (WPR) of subcontractors is an essential element for improving project performance. Previous research mainly focused on the consequence of the WPR variability of a subcontractor on the following subcontractors in the project task-sequence. Construction industry lacks a good understanding of the social aspect of the subcontractors' WPR. Plausibly and arguably, construction subcontractors and their interactions/relationships in a project constitute a network, conceptualized as a “social network”. “Social conformity” is one of the various social influence types that results in a change of performance/behavior in order to fit in a group. This research aims to understand how conformity plays a role in the subcontractors' performance particularly in their WPR. The objective of this paper is to develop an analytical approach to 1) demonstrate the impact of conformity on the WPR of subcontractors, and 2) identify the role of social network in conformity occurrence in a construction project. Two construction projects, each including a general contractor overseeing several subcontractors, were studied. Findings show that deviation from norms decreases as project proceeds. It also shows that the tendency of subcontractors to follow the norms of their neighborhood (local) is higher than their willing to follow the project norm (global). The research contributes to the body of knowledge as it proposes a social network based approach for the first time to explore how the subcontractors' WPR in a construction project can be under the influence of the conformity phenomenon. Understanding the subcontractors' manner can be useful for project managers when they need to establish a long-term working relationship with a particular subcontractor, or when they need to know much effort is necessary to spend on improvement initiatives of planning reliability.}, journal={AUTOMATION IN CONSTRUCTION}, author={Abbasian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2017}, month={Jun}, pages={1–12} }
 @article{hajifathalian_howell_wambeke_hsiang_liu_2016, title={"Oops" Simulation: Cost-Benefits Trade-Off Analysis of Reliable Planning for Construction Activities}, volume={142}, ISSN={["1943-7862"]}, DOI={10.1061/(asce)co.1943-7862.0001135}, abstractNote={Abstract“The Oops Game” explores the question, how much should be invested in planning? The simulation offers the opportunity to reduce the risk of an “Oops” by collecting more information or to go ahead and make the choice with the information at hand. There are two extreme strategies. Nothing is invested in planning in the so-called Guts-ball approach, but this increases the likelihood that an “Oops” will occur and thus increases the cost to complete the project. The second strategy is to invest in planning before attempting to build. This will increase the cost of planning upfront, but may reduce the risk and cost of an “Oops” in building. In reality, the cost and value of planning depends on the complexity level of the project, the amount of uncertainty that we need to deal with it, and the cost of an “Oops.” We used computer simulation to show how the value of planning is sensitive to those factors. The results showed that the project with the reliable planning strategy had a 35% higher productivity ...}, number={8}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT}, author={Hajifathalian, Kiarash and Howell, Gregory and Wambeke, Brad W. and Hsiang, Simon M. and Liu, Min}, year={2016}, month={Aug} }
 @article{javanmardi_abbasian-hosseini_liu_hsiang_2016, title={Analysis of Workflow Variability's Impacts on Trade and Project Performance}, volume={145}, ISSN={["1877-7058"]}, DOI={10.1016/j.proeng.2016.04.075}, abstractNote={Variability, defined as the deviation of production capacity from an expected average, has a negative impact on the productivity of downstream trades and the entire system. It increases project duration, lost capacities and inventory of the downstream trades. This paper, using Parade Game Simulation, aims to identify the key trade(s) of a single-line production system that contribute(s) the most in reducing/increasing the project duration, total lost capacity and total inventory buffer. The simulation model includes seven trades with two different variability levels. A cooperative game theory was utilized to investigate how the productivity of downstream trades and the entire system is affected by the location of variability. This research revealed the key trades and strategic assignments of trades to maximize the trade and system performance. The findings are beneficial to construction managers as it helps them to manage the workflow efficiently by focusing on the key trades.}, journal={ICSDEC 2016 - INTEGRATING DATA SCIENCE, CONSTRUCTION AND SUSTAINABILITY}, author={Javanmardi, Ashtad and Abbasian-Hosseini, S. Alireza and Liu, Min and Hsiang, Simon M.}, year={2016}, pages={281–287} }
 @article{abbasian-hosseini_leming_liu_2016, title={Effects of Idle Time Restrictions on Excess Pollution from Construction Equipment}, volume={32}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(ASCE)ME.1943-5479.0000408}, DOI={10.1061/(asce)me.1943-5479.0000408}, abstractNote={AbstractConstruction vehicles and equipment contribute to air pollution. To reduce pollution, numerous state and local jurisdictions limit the amount of time diesel engine vehicles or equipment can run at idle without shutting down. These restrictions vary widely indicating a need for improved understanding of the relationships between pollutant emissions and regulations establishing a maximum idle time in a construction setting. Previous studies have found that a reduction in operational efficiency will increase the amount of excess pollution, that is, the amount of pollution created in excess of that emitted by a construction operation under ideal conditions. Shutting down an engine can create a delay in re-entering the work stream and, therefore, reduce operational efficiency. In another study, the authors found that excess pollution would be minimal with a reasonably well-balanced, minimum or near minimum cost, construction equipment fleet composed of a single wheel loader (WL) working with different ...}, number={2}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Abbasian-Hosseini, S. Alireza and Leming, Michael L. and Liu, Min}, year={2016}, month={Mar}, pages={04015046} }
 @article{russell_liu_hsiang_2016, title={Planning for uncertainty: Use of structural equation modelling to determine the causal structure of time buffer allocation}, volume={33}, number={10}, journal={Construction Management and Economics}, author={Russell, M. M. and Liu, M. and Hsiang, S. M.}, year={2016}, pages={783–798} }
 @inproceedings{abbasian-hosseini_howell_liu_2016, title={Relationship between On-Site Planning Efforts and Work Plan Reliability}, ISBN={9780784479827}, url={http://dx.doi.org/10.1061/9780784479827.212}, DOI={10.1061/9780784479827.212}, abstractNote={Adequate planning is essential to successfully deliver a project. Construction site managers’ “planning” efforts include various levels: (1) identifying the sequence and timing of activities; (2) scheduling and organizing the wherewithal to perform the job; (3) planning with other project teams to coordinate for shared resources and/or interaction; and (4) designing the production system. Although there are several studies on construction project planning and its outcomes, the research pertaining to the effect of the on-site planning during construction on the performance is very limited. This research, via a questionnaire-based survey, identifies the relationship between the site manager’s effort on the 2nd and 3rd levels of planning and the work plan reliability (WPR), measured by the plan percent complete (PPC). The survey was distributed to site managers of general contractors and subcontractors in North Carolina, US. Eighty three useable survey responses were collected and classified based on management level, type of work, and project characteristics. Correlation analysis results show that there is a significant correlation between the efforts at the 3rd level of planning and the PPC average for the subcontractors. Results also show that the PPC variation decreases when more efforts are devoted on the 3rd level of planning.}, publisher={American Society of Civil Engineers}, author={Abbasian-Hosseini, S. Alireza and Howell, Gregory and Liu, Min}, year={2016}, month={May} }
 @article{patanakul_kwak_zwikael_liu_2016, title={What impacts the performance of large-scale government projects?}, volume={34}, ISSN={["1873-4634"]}, DOI={10.1016/j.ijproman.2015.12.001}, abstractNote={Government projects and programs contribute to national growth at a great magnitude. However, records show that they are not well managed, even when project teams follow established project management principles. As a result, this study aimed at identifying key characteristics of government projects and programs, and recommending how they can be used to improve performance. This paper analyzed 39 public projects undertaken in the U.S., UK, and Australia and reviewed officially by the national audit offices and government agencies, including the Los Angeles Metro, London Heathrow's Terminal 5, and the fatal Australia's Homeowner Insulation Program. Based on this analysis the paper suggests six key characteristics, 17 practical recommendations, and six research propositions. These findings can support government project managers to utilize project management approaches according to project characteristics. This paper can support policy makers and government officials in improving the approaches for the management of government projects and programs}, number={3}, journal={INTERNATIONAL JOURNAL OF PROJECT MANAGEMENT}, author={Patanakul, Peerasit and Kwak, Young Hoon and Zwikael, Ofer and Liu, Min}, year={2016}, month={Apr}, pages={452–466} }
 @article{russell_liu_howell_hsiang_2015, title={Case Studies of the Allocation and Reduction of Time Buffer through Use of the Last Planner System}, volume={141}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(ASCE)CO.1943-7862.0000900}, DOI={10.1061/(asce)co.1943-7862.0000900}, abstractNote={AbstractBuffers are used in construction to absorb variation caused by the inherent complexity and uncertainty present in construction projects. The case studies presented here focus on time buffer added to construction task durations. For this research, time buffer is defined as extra time added during planning to individual task durations to compensate for uncertainty and protect against workflow variation. Two case studies were conducted with one involving a mechanical contractor and the other involving a large general contractor. This research contributes to the body of knowledge by: (1) investigating the time buffer impact on project performance; (2) empirically demonstrating the effect of last planner system (LPS) on reducing time buffer and increasing percent planned complete (PPC); and (3) examining the buffer trends of different trades and activity types. The findings demonstrate LPS as an example of an effective planning strategy for construction managers in improving project performance and hel...}, number={2}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Russell, Marion M. and Liu, Min and Howell, Gregory and Hsiang, Simon M.}, year={2015}, month={Feb}, pages={04014068} }
 @article{abbasian-hosseini_liu_leming_2015, title={Comparison of Least-Cost and Least-Pollution Equipment Fleet Configurations Using Computer Simulation}, volume={31}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(ASCE)ME.1943-5479.0000360}, DOI={10.1061/(asce)me.1943-5479.0000360}, abstractNote={AbstractConstruction vehicles and equipment, like all other fuel-powered vehicles, contribute to air pollutant emissions, such as nitrogen oxides (NOX) and particulate matter (PM). The U.S. Environmental Protection Agency has established standards for pollutant emissions for different tiers of equipment to attain a “least-pollution” equipment spread or fleet. Although using higher-tier vehicles and equipment can reduce pollutant emissions under otherwise identical conditions, policies and contractor operations can also significantly affect the total pollutant emitted for a given amount of work, such as cubic yards of earth moved or tons of surface course placed. Previous studies demonstrated the direct relationship between pollutant emissions and operational productivity and the quantitative effects of that relationship using real-world emissions data. This paper describes the results of a study conducted using computer-based simulation techniques to compare costs and pollutant emissions for a typical ear...}, number={6}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Abbasian-Hosseini, S. Alireza and Liu, Min and Leming, Michael}, year={2015}, month={Nov}, pages={04015003} }
 @article{russell_hsiang_liu_wambeke_2014, title={Causes of Time Buffer and Duration Variation in Construction Project Tasks: Comparison of Perception to Reality}, volume={140}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000819}, DOI={10.1061/(asce)co.1943-7862.0000819}, abstractNote={AbstractDue to the inherent nature of the construction industry, all construction projects have some amount and type of uncertainty. This uncertainty can lead to variation in project task durations from what was originally planned. As a result, construction personnel compensate for the uncertainty by adding a time buffer to absorb variations in the work plan. For the purpose of this research, a time buffer is defined as the amount of time included in task durations to compensate for uncertainty and to protect against variation. Variation is defined as the difference between the planned and actual task duration. Although previous research acknowledges time buffer additions, the root causes for adding a buffer have not been thoroughly researched. A nationwide survey was administered to project managers, superintendents, and foremen to identify the most severe reasons for adding time buffers to construction task durations. The root causes of variation have been previously identified and are used as the compa...}, number={6}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Russell, Marion M. and Hsiang, Simon M. and Liu, Min and Wambeke, Brad}, year={2014}, month={Jun}, pages={04014016} }
 @book{kwak_liu_patanakul_zwikael_2014, place={Newtown Square, PA}, title={Challenges and Best Practices of Managing Government Projects and Programs}, ISBN={978-1-62825-065-7.}, publisher={Project Management Institute Inc}, author={Kwak, Y. and Liu, M. and Patanakul, P. and Zwikael, O.}, year={2014} }
 @article{abbasian-hosseini_hsiang_leming_liu_2014, title={From Social Network to Data Envelopment Analysis: Identifying Benchmarks at the Site Management Level}, volume={140}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(ASCE)CO.1943-7862.0000875}, DOI={10.1061/(ASCE)CO.1943-7862.0000875}, abstractNote={AbstractIt is widely accepted in the construction industry that contract documents, specifying the responsibility and risk of each participant, are the basis for project managers’ and superintendents’ decision making (DM). However, in practice strict adherence to the formal procedures and chains of command would not always be possible without an unacceptable expenditure of time and money. Although much attention is given to the decisions at the project manager and superintendent level, the underlying rules and mechanisms for the moment-to-moment DM at the site management level has not been documented. In this paper, a social network (SN)–based data envelopment analysis (DEA) benchmarking procedure (SDBP), which combines DEA (assessing the relative efficiency of DM units) and SN (concentrating on the relationships amongst DM units) to identify the benchmarks for the inefficient specialty trades (STs). This paper also uses a case study to illustrate how to implement the SDBP. This research contributes to th...}, number={8}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Abbasian-Hosseini, S. Alireza and Hsiang, Simon M. and Leming, Michael L. and Liu, Min}, year={2014}, month={Aug}, pages={04014028} }
 @article{wambeke_liu_hsiang_2014, title={Task Variation and the Social Network of Construction Trades}, volume={30}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(asce)me.1943-5479.0000219}, DOI={10.1061/(asce)me.1943-5479.0000219}, abstractNote={AbstractConstruction projects can be complex and managers are faced with the challenge of managing multiple trades working on a large number of interdependent tasks. When one trade or task experiences variation, defined as the time difference between what was planned and what occurred for this research, additional trades or tasks can be impacted. This can result in a disrupted project schedule and reduced productivity. A case study involving a general contractor (GC) building a $50 million, 150,000 sq ft data collection center was conducted. Both starting time and task duration variation data was collected on approximately 1,200 tasks performed by over 40 trades. A risk assessment matrix was used to determine which causes of variation posed the greatest risk to project performance. Pajek, a social network analysis software, was used to illustrate the organizational structure of the key trades throughout the project based on spatial proximity. It was found that material delivery and not having prerequisite...}, number={4}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Wambeke, Brad W. and Liu, Min and Hsiang, Simon M.}, year={2014}, month={Jul}, pages={05014008} }
 @article{russell_howell_hsiang_liu_2013, title={Application of Time Buffers to Construction Project Task Durations}, volume={139}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000735}, DOI={10.1061/(asce)co.1943-7862.0000735}, abstractNote={AbstractFor this research, a time buffer is defined as the extra time added during planning to individual task durations to compensate for uncertainty and protect against workflow variation to assure a predictable hand-off to subsequent crews. Although previous research has acknowledged this addition of time buffers, their use in practice has not been studied. This paper reports on what causes people to add and size time buffers. A nationwide survey was administered to project managers, superintendents, and foremen to identify the most frequent and severe reasons for adding time buffers to construction task durations. Forty-seven buffer factors were grouped into nine categories: project characteristics, prerequisite work, detailed design/working method, labor force, tools and equipment, material and components, work/jobsite conditions, management/supervision/information flow, and weather. Contributions to the body of knowledge include (1) identifying the 12 most frequent and severe causes of time buffer; ...}, number={10}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Russell, Marion M. and Howell, Gregory and Hsiang, Simon M. and Liu, Min}, year={2013}, month={Oct}, pages={04013008} }
 @article{vaughan_leming_liu_jaselskis_2013, title={Cost-Benefit Analysis of Construction Information Management System Implementation: Case Study}, volume={139}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000611}, DOI={10.1061/(asce)co.1943-7862.0000611}, abstractNote={AbstractIn construction projects, construction managers spend a significant portion of their time gathering project data, assessing production rates, communicating with project participants, and tracking project quality. Executing those tasks manually reduces efficiency and can result in less effective project management operations. In order to improve efficiency of information process flow, various types of construction information management systems (CIMSs) have been introduced to construction projects. However, due to the difficulty of tracking fragmental and illusive data, measuring the cost and benefit of the implementation and evaluating the trade-off remain a challenge for construction practitioners. This paper’s contributions to the body of knowledge include (1) proposing a framework to assess tangible and semitangible or intangible costs and benefits of innovative construction technology application, (2) determining costs and benefits of the use of CIMSs by conducting a product-specific case stud...}, number={4}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Vaughan, Joshua L. and Leming, Michael L. and Liu, Min and Jaselskis, Edward}, year={2013}, month={Apr}, pages={445–455} }
 @article{hollar_rasdorf_liu_hummer_arocho_hsiang_2013, title={Preliminary Engineering Cost Estimation Model for Bridge Projects}, volume={139}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000668}, DOI={10.1061/(asce)co.1943-7862.0000668}, abstractNote={AbstractThis paper addresses one of the costs of new bridges, i.e., the cost of doing the preliminary engineering (PE). This particular aspect of cost has largely been neglected because of the difficulty in obtaining appropriate data. Typically, PE costs are determined as a percentage of construction costs, disregarding other project-specific parameters. Bridge projects let by the North Carolina (NC) DOT between 2001 and 2009 were reviewed. From an analysis of these 461 projects, the writers developed statistical models linking variation in PE costs with distinctive project parameters. The primary contribution this paper makes to the body of knowledge is the finding that PE cost estimates for bridge projects are commonly and significantly underestimated. The writers found that bridge projects exhibited a mean PE cost ratio of 28%. This result is significantly greater than the percentage used in practice. An investigation of data sources related to bridge projects, a description of regression techniques ap...}, number={9}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Hollar, Donna A. and Rasdorf, William and Liu, Min and Hummer, Joseph E. and Arocho, Ingrid and Hsiang, Simon M.}, year={2013}, month={Sep}, pages={1259–1267} }
 @article{liu_rasdorf_hummer_hollar_parikh_2013, title={Preliminary Engineering Cost-Estimation Strategy Assessment for Roadway Projects}, volume={29}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(asce)me.1943-5479.0000137}, DOI={10.1061/(asce)me.1943-5479.0000137}, abstractNote={Preliminary engineering (PE) for a roadway project encompasses two efforts: planning to minimize the physical, social, and human environmental impacts of projects and engineering design to deliver the best alternative. State transportation agencies strive to manage these efforts efficiently, seeking to maximize the utilization of limited funding and workforce productivity. Managers need a feasible PE budget, considering both cost and time, early in project development. The results reported herein will provide engineers and managers with a comparative investigation evaluating different strategies for establishing a PE budget during the preconstruction phase of roadway project development. Cost data were obtained for 188 North Carolina roadway projects built between 1999 and 2009. An analysis of the North Carolina DOT data yielded an overall mean ratio of PE cost to estimated construction cost (the PE cost ratio) of 11.7%. The multiple linear regression model was used to develop prediction models to forecast the PE cost ratio of future roadway projects. It was found that while differing regression strategies could reduce prediction error, the improvement was small. In terms of simplicity, using the historical means applicable for widening projects (13.3%), rehabilitation/resurfacing projects (7.7%), and new location/interchange projects (16.5%) proved advantageous over regression modeling because a project manager would not have to estimate any project-specific values at the earliest stages of project development. The lowest of these historical means was significantly different than the two higher means (7.7% versus 13.3% and 16.5%); however, the difference between the two higher means (13.3% versus 16.5%) was not statistically significant. The study analyses also found a significant correlation between a project’s PE cost ratio and its PE duration, suggesting that further investigation into PE duration of transportation projects is warranted.}, number={2}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Liu, Min and Rasdorf, William and Hummer, Joseph E. and Hollar, Donna A. and Parikh, Shalin C.}, year={2013}, month={Apr}, pages={150–157} }
 @article{wang_liu_hsiang_leming_2012, title={Causes and Penalties of Variation: Case Study of a Precast Concrete Slab Production Facility}, volume={138}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000475}, DOI={10.1061/(asce)co.1943-7862.0000475}, abstractNote={Concrete precast plants require strict control over and adherence to the timing and sequence of operations. Variation for this research is divided into the variation in task starting time (the difference between the planned and the actual starting time) and the variation in task duration (the difference between the planned and the actual task duration). This study determined causes of variation in task starting time and duration of precast concrete slab production tasks. It also identified penalties associated with not reducing variation, which include an increase in project duration, Work in-Progress (WIP) and cost and a decrease in labor productivity. Additionally, two execution policies (keeping laborers waiting before preconditions are ready and keeping laborers busy) in the face of variation were compared by using STROBOSCOPE simulation techniques. It was found that simply keeping workers busy is insufficient for managing variation. Management effort should be devoted to eliminate causes of variation in the planning stage to make a reliable work plan. The results will help prefabricators to understand causes and penalties of variation, which is the starting point of attacking and reducing it. Although this study is based on a concrete slab production facility, this research can have a broader effect on the construction industry because the research method and simulation models developed in this study are applicable to other fabrication processes as well.}, number={6}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Wang, Chao and Liu, Min and Hsiang, Simon M. and Leming, Michael L.}, year={2012}, month={Jun}, pages={775–785} }
 @article{hajifathalian_wambeke_liu_hsiang_2012, title={Effects of Production Control Strategy and Duration Variance on Productivity and Work in Process: Simulation-Based Investigation}, volume={138}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000517}, DOI={10.1061/(asce)co.1943-7862.0000517}, abstractNote={AbstractImproving productivity and reducing work-in-process are two activities that can improve project performance, but are often difficult to accomplish. The construction process is complex and consists of a large number of interdependent and sequential tasks. Construction activities are simulated as serial production lines, using state- and resource-based simulation of construction processes simulation models, to investigate the effects that different production control strategies (push/pull and balanced/unbalanced) have on productivity and work-in-process. The sensitivity to task duration variance is also examined for different working strategies. Simulation results are used to compare the models based on their performance. In the presence of duration variance, push strategies result in higher productivity, whereas pull strategies result in lower amounts of work-in-process. Pull strategies are more sensitive to the presence of duration variance. Work-in-process is also a function of the coefficient of...}, number={9}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Hajifathalian, Kiarash and Wambeke, Brad W. and Liu, Min and Hsiang, Simon M.}, year={2012}, month={Sep}, pages={1035–1043} }
 @inproceedings{liu_rasdorf_hollar_hummer_parikh_2012, title={Predicting the Preliminary Engineering Duration of Bridge Projects}, ISBN={9780784412329}, url={http://dx.doi.org/10.1061/9780784412329.051}, DOI={10.1061/9780784412329.051}, abstractNote={Preliminary engineering (PE) is a critical preconstruction phase of infrastructure projects, encompassing the initial planning and design processes necessary for successful commencement and completion of a project. The duration of PE influences both the cost and schedule of any civil infrastructure project. Numerous studies targeted at construction duration estimation exist, but few address strategies to estimate PE duration. This study sought to identify the project factors that influenced the PE duration of bridge projects and to determine if regression modeling with those factors would provide a feasible tool for PE duration estimation. Some 416 bridge projects conducted by the North Carolina Department of Transportation (NCDOT) served as the analysis sample. Among the project factors investigated, four descriptive factors significantly influenced PE duration: geographical area of the state, classification of the required National Environmental Policy Act (NEPA) document, bridge construction scope, and responsible party preparing the NEPA document. For validation purposes, the authors randomly extracted 60 of the 416 bridge projects before regression modeling. Regression models achieved a mean absolute percentage error (MAPE) of 21% when applied to the validation set. Comparatively, using the mean PE duration of 66 months as a single point estimator, the MAPE was 22% for the same validation set. Based on these results, the project team recommended that the NCDOT can use the regression equation to estimate PE duration. It is also clear that this is a difficult problem that deserves further research attention.}, booktitle={Construction Research Congress 2012}, publisher={American Society of Civil Engineers}, author={Liu, Min and Rasdorf, William and Hollar, Donna A. and Hummer, Joseph E. and Parikh, Shalin C.}, year={2012}, month={May} }
 @article{wang_liu_2012, title={Prices of Highway Resurfacing Projects in Economic Downturn: Lessons Learned and Strategies Forward}, volume={28}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(asce)me.1943-5479.0000094}, DOI={10.1061/(asce)me.1943-5479.0000094}, abstractNote={AbstractIt was observed that economic downturns were typically associated with oil price shocks. Based on historical construction data from highway resurfacing projects in Kentucky, this paper investigates the relationship between oil price, Kentucky diesel price index (KDPI), Kentucky asphalt price index (KAPI), and construction cost of highway resurfacing projects. It was found that the bidding price of a commonly used asphalt mixture was significantly affected by four factors: KDPI, KAPI, number of bidders, and a recession factor primarily attributable to the “sticky prices” effect. The KDPI and KAPI can be estimated from the oil price by regression models. The sensitivity of the asphalt mixture and resurfacing project costs to oil price variation was analyzed. On the basis of the analysis result, it is suggested that the highway agencies may avoid the oil price peak typically preceding a recession and take advantage of the oil price plunge after the recession starts. However, in the long run, the agen...}, number={4}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Wang, Yuhong and Liu, Min}, year={2012}, month={Oct}, pages={391–397} }
 @article{wambeke_liu_hsiang_2012, title={Using Last Planner and a Risk Assessment Matrix to Reduce Variation in Mechanical Related Construction Tasks}, volume={138}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000444}, DOI={10.1061/(asce)co.1943-7862.0000444}, abstractNote={AbstractVariation, defined for this research as the time difference between what was planned and what actually happened, is important as it can affect the productivity performance of construction tasks. The construction process is complex and consists of a large number of interdependent tasks. When the starting time and/or duration of one task varies, it can affect other downstream tasks and result in disruptions to the schedule and/or decreased productivity. This research examined the effect of using a risk assessment matrix in conjunction with the Last Planner System (LPS) method to reduce and/or eliminate task duration variation. A case study was conducted involving a mechanical contractor who specializes in plumbing, heating, ventilation, and air conditioning. The company compared the performance of two separate, but similar projects. The LPS method was used with one of the projects and the company’s traditional planning system was used with the other (i.e., not using the LPS system). A total of 16 we...}, number={4}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Wambeke, Brad W. and Liu, Min and Hsiang, Simon M.}, year={2012}, month={Apr}, pages={491–498} }
 @article{wambeke_liu_hsiang_2012, title={Using Pajek and Centrality Analysis to Identify a Social Network of Construction Trades}, volume={138}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000524}, DOI={10.1061/(asce)co.1943-7862.0000524}, abstractNote={AbstractConstruction project managers are often faced with the challenge of managing a complex construction process consisting of multiple trades working on a large number of interdependent tasks. A social network is a pattern of ties that exist between different entities (i.e., people, organizations, countries). There is an underlying social network of trades that exists with a construction project and recognizing it can help a management team succeed in this challenging environment. A $50 million project involving 43 trades was studied over a 28-week period. Pajek, a social network analysis program, was used to generate a series of 14 social networks for the trades involved. Both degree and eigenvector centrality were analyzed to reflect the distribution of relationships through the network and to identify the key trades. This research is useful to project managers and is significant as it outlines and illustrates a method of identifying the underlying network and associated key trades of a construction...}, number={10}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Wambeke, Brad W. and Liu, Min and Hsiang, Simon M.}, year={2012}, month={Oct}, pages={1192–1201} }
 @article{lai_liu_ling_2011, title={A comparative study on adopting human resource practices for safety management on construction projects in the United States and Singapore}, volume={29}, ISSN={0263-7863}, url={http://dx.doi.org/10.1016/j.ijproman.2010.11.004}, DOI={10.1016/j.ijproman.2010.11.004}, abstractNote={Good project management outcomes include completing projects to an acceptable level of quality, within budget and on time. As construction accidents may cause project delays, safety management plays an important role in a project's timely completion. This study aims to undertake a comparative study of HR practices adopted for safety management on construction projects in the United States (US) and Singapore and to investigate the relationship between HR practices and construction safety management outcomes (severity and frequency of accidents). The research method included exploratory interviews and industry surveys of contractors in the US and Singapore by email and post. Data were collected using structured questionnaires. Compared to Singapore contractors, the results show that US contractors' project management practices place significantly more emphasis on highlighting organizational safety values to new workers and taking working experience into account during the selection process. On the other hand, Singapore contractors place more emphasis on providing appropriate rest areas for workers. Many HR practices are significantly correlated with safety management outcomes. These include: taking age into consideration during selection process and giving feedback to workers about their unsafe behaviour. It is recommended that project managers adopt relevant HR practices that lead to more effective safety management on construction projects.}, number={8}, journal={International Journal of Project Management}, publisher={Elsevier BV}, author={Lai, Diana N.C. and Liu, Min and Ling, Florence Y.Y.}, year={2011}, month={Dec}, pages={1018–1032} }
 @article{ibbs_liu_2011, title={An improved methodology for selecting similar working days for measured mile analysis}, volume={29}, ISSN={0263-7863}, url={http://dx.doi.org/10.1016/j.ijproman.2010.07.006}, DOI={10.1016/j.ijproman.2010.07.006}, abstractNote={Abstract Quantifying economic losses on construction projects caused by labor inefficiencies is often a difficult and tedious task. A widely accepted way to quantify such losses is by using the “measured mile” approach. This technique compares the productivity achieved during an unimpacted or minimally impacted time period with productivity realized during an impacted period. The dependability of the periods that are chosen is vital and plays a key role in the determination of merit, liability and quantum. The work performed during the measured mile period should be substantially similar to the work that was affected. As currently practiced though, choosing the periods for measured mile analysis is usually made in a largely subjective manner. The objective of this article is to introduce and illustrate the statistical clustering method as a tool for selecting the similar working periods. This new approach is advocated because it determines similarity of work condition using objective criteria. The method is agile and can be easily applied in practice by project managers or construction consultants. In this paper the factors that affect the similarity of work are identified, and the clustering procedure is developed. An example is also included to show how the method works in practice.}, number={6}, journal={International Journal of Project Management}, publisher={Elsevier BV}, author={Ibbs, William and Liu, Min}, year={2011}, month={Aug}, pages={773–780} }
 @article{wambeke_hsiang_liu_2011, title={Causes of Variation in Construction Project Task Starting Times and Duration}, volume={137}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)co.1943-7862.0000342}, DOI={10.1061/(asce)co.1943-7862.0000342}, abstractNote={In this research, variation is defined as the time difference between what was planned and what actually happened in terms of task starting times and duration. Variation in construction tasks is important as it can impact productivity performance. Construction projects consist of a large number of interdependent tasks. When the starting time and/or duration of one task varies, it can affect other downstream tasks and result in disruptions to the schedule and/or decreased productivity. The construction process is complex and involves numerous people with different levels of responsibility, which makes identifying the root causes of the variation difficult. A nationwide survey was administered to workers, foremen, and project managers to identify the most prevalent causes and magnitude of both starting time and task duration variation. Fifty individual causes of variation were divided into eight categories: prerequisite work, detailed design/working method, labor force, tools and equipment, material and components, work/job site conditions, management/supervision/information flow, and weather or external conditions. This research examined the similarities and differences in perceptions between craft workers, foremen, and project managers in terms of starting time and task duration variation. The top eight causes of starting time variation and top nine causes of task duration variation were identified. The research also quantitatively analyzed the underlying structure of the causes of variation using factor analysis. This was done by grouping the 50 individual causes into nine orthogonal factors that represent the underlying structure of the affecting causes. The findings will help construction project managers and field managers focus on the root causes of variation during planning in order to develop effective strategies to reduce variation and improve project productivity performance.}, number={9}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Wambeke, Brad W. and Hsiang, Simon M. and Liu, Min}, year={2011}, month={Sep}, pages={663–677} }
 @article{liu_ballard_ibbs_2011, title={Work Flow Variation and Labor Productivity: Case Study}, volume={27}, ISSN={0742-597X 1943-5479}, url={http://dx.doi.org/10.1061/(asce)me.1943-5479.0000056}, DOI={10.1061/(asce)me.1943-5479.0000056}, abstractNote={Different types of flow variation and how they affect construction project performance have been studied by previous researchers. One aspect that has not been well researched is how work flow variation and labor productivity are related in construction practice. To study that issue, 134 weeks of project production data were collected and analyzed to explore this relationship. Labor productivity was found to be positively correlated with Percent Plan Complete (PPC), a measure of work flow variation. The relationship between productivity and the ratio of total task completion to planned tasks, weekly workload, weekly work output, and weekly work hours was also studied, and no significant correlation was found. The results suggest that productivity is not improved by completing as many tasks as possible regardless of the plan, nor from increasing workload, work output, or the number of work hours expended. In contrast, productivity does improve when work flow is made more predictable. These findings can help...}, number={4}, journal={Journal of Management in Engineering}, publisher={American Society of Civil Engineers (ASCE)}, author={Liu, Min and Ballard, Glenn and Ibbs, William}, year={2011}, month={Oct}, pages={236–242} }
 @inproceedings{wambeke_liu_hsiang_2010, title={Causes of Variation in Construction Task Starting Times and Duration}, ISBN={9780784411094}, url={http://dx.doi.org/10.1061/41109(373)98}, DOI={10.1061/41109(373)98}, abstractNote={Variation in construction task starting time and duration can impact overall productivity performance, yet their root causes often remain unclear. In this research, variation is defined as the difference between what was planned and what actually happened. This paper examines the variation in starting time and the duration of construction tasks while considering 50 productivity factors. The 50 factors were divided into eight categories: prerequisite work, detailed design/working method, labor force, tools and equipment, material and components, work/jobsite conditions, management/supervision/information flow, and weather or external conditions. A nationwide survey involving craft workers, foremen, and project managers was employed and serves to offer valuable insight on the causes and impacts of variation. The findings will help construction project managers and field managers identify the common risk factors, focus on the root causes of variation in planning phase, develop effective strategies to reduce variation, and improve the project.}, booktitle={Construction Research Congress 2010}, publisher={American Society of Civil Engineers}, author={Wambeke, Brad and Liu, Min and Hsiang, Simon M.}, year={2010}, month={May} }
 @article{ling_liu_woo_2009, title={Construction fatalities in Singapore}, volume={27}, ISSN={0263-7863}, url={http://dx.doi.org/10.1016/j.ijproman.2008.11.002}, DOI={10.1016/j.ijproman.2008.11.002}, abstractNote={This study investigates proximal causes to 40 fatalities between 2006 and 2008 in Singapore’s construction industry. We statistically analyzed the data and found 11 characteristics of deceased workers, types of work, and the environment. Construction fatality causes in the US between 2003 and 2006 were also analyzed and compared with the data in Singapore. We developed 41 strategies to minimize fatalities. We interviewed seven Singapore and US construction safety managers for their opinions on the effectiveness of the strategies. We conclude that in addition to those recommended strategies, changes in organizational safety culture, enhancement of the penalty system, and effective communication are critical to improve safety performance in Singapore’s construction industry.}, number={7}, journal={International Journal of Project Management}, publisher={Elsevier BV}, author={Ling, Florence Yean Yng and Liu, Min and Woo, Yue Chiau}, year={2009}, month={Oct}, pages={717–726} }
 @article{yean yng ling_liu_2005, title={Factors considered by successful and profitable contractors in mark-up size decision in Singapore}, volume={40}, ISSN={0360-1323}, url={http://dx.doi.org/10.1016/j.buildenv.2004.12.001}, DOI={10.1016/j.buildenv.2004.12.001}, abstractNote={Identifying the optimum mark-up for a project increases the chance of winning the tender. The aim of this study is to investigate the factors considered by more successful and profitable contractors in mark-up size decision. From the literature, 52 factors that may affect mark-up were identified. A postal survey was conducted to whether contractors felt that the factors are important in determining mark-ups. The questionnaire requested respondents to indicate on a five-point scale the importance of various factors. They were also asked the usual profitability level in their successful projects and their success rates in tendering. Data were collected via mailed questionnaire. Twenty-one of the 52 factors were found to be important. Of these, factors relating to client characteristics (payment record, size and type of client) are the most significant. Contractors who are profitable and successful would place more emphasis on factors that affect schedule-cost-quality of the project. It is recommended that contractors who are less profitable and successful take note of these findings.}, number={11}, journal={Building and Environment}, publisher={Elsevier BV}, author={Yean Yng Ling, Florence and Liu, Min}, year={2005}, month={Nov}, pages={1557–1565} }
 @article{ibbs_liu_2005, title={Improved Measured Mile Analysis Technique}, volume={131}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)0733-9364(2005)131:12(1249)}, DOI={10.1061/(asce)0733-9364(2005)131:12(1249)}, abstractNote={Quantifying lost labor productivity on construction projects is difficult and sometimes subjective. A widely accepted way to quantify losses is the “measured mile” approach. It compares periods of a project that have been impacted by change to those that have not been impacted. As currently practiced the measured mile relies on subjectively identifying that reference period. In this paper the measured mile and a variant, the baseline method, are analyzed and compared to a new, proposed statistical clustering method. This new approach is advocated because it determines its reference period using objective criteria. A case study is included to show how the three methods work, and advantages and disadvantages of each method are presented in this paper.}, number={12}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Ibbs, William and Liu, Min}, year={2005}, month={Dec}, pages={1249–1256} }
 @article{liu_ling_2005, title={Modeling a Contractor’s Markup Estimation}, volume={131}, ISSN={0733-9364 1943-7862}, url={http://dx.doi.org/10.1061/(asce)0733-9364(2005)131:4(391)}, DOI={10.1061/(asce)0733-9364(2005)131:4(391)}, abstractNote={The estimation of markup is a difficult process for contractors in a changeable and uncertain construction environment. In this study, a fuzzy logic-based artificial neural network (ANN) model, called the fuzzy neural network (FNN) model, is constructed to assist contractors in making markup decisions. With the fuzzy logic inference system integrated inside, the FNN model provides users with a clear explanation to justify the rationality of the estimated markup output. Meanwhile, with the self-learning ability of ANN, the accuracy of the estimation results is improved. From a survey and interview with local contractors, the factors that affect markup estimation and the rules applied in the markup decision are identified. Based on the finding, both ANN and FNN models were constructed and trained in different project scenarios. The comparison of the two models shows that FNN will assist contractors with markup estimation with more accurate results and convincing user-defined linguistic rules inside.}, number={4}, journal={Journal of Construction Engineering and Management}, publisher={American Society of Civil Engineers (ASCE)}, author={Liu, Min and Ling, Yean Yng}, year={2005}, month={Apr}, pages={391–399} }
 @article{ibbs_liu_2005, title={System Dynamic Modeling of Delay and Disruption Claims}, volume={47}, number={6}, journal={AACE Cost Engineering}, author={Ibbs, W. and Liu, M.}, year={2005}, pages={12–15} }
 @article{ling_liu_2004, title={Using neural network to predict performance of design-build projects in Singapore}, volume={39}, ISSN={0360-1323}, url={http://dx.doi.org/10.1016/j.buildenv.2004.02.008}, DOI={10.1016/j.buildenv.2004.02.008}, abstractNote={Design-build (DB) project success may be operationalised into 11 performance metrics. 65 factors that may affect DB project success are identified. Using data from 33 DB projects, correlation analysis shows that there are several factors that affect each performance metric significantly. Artificial neural network (ANN) technique is used to construct the models to predict project performance, and these models are tested using data from five new projects. This study finds that six performance metrics can be predicted with a reasonable degree of accuracy: project intensity; construction and delivery speeds; turnover, system and equipment quality. The key variables that affect project performance may be attributed to both contractors and clients. To ensure project success, contractors should have adequate staffing level, a good track record for completion on budget, and ability in financial management and quality control. Consultants should have a high level of construction sophistication, and have handled DB projects in the past. Clients also play an important part in ensuring DB project success. They would need to have construction experience and handled DB projects in the past. In addition, they should decide on the optimal level of design completion when the budget is fixed and tenders are invited. It is recommended that owners and contractors take note of the factors identified in this study, which significantly affect DB project performance.}, number={10}, journal={Building and Environment}, publisher={Elsevier BV}, author={Ling, Florence Yean Yng and Liu, Min}, year={2004}, month={Oct}, pages={1263–1274} }
 @article{liu_ling_2003, title={Using fuzzy neural network approach to estimate contractors’ markup}, volume={38}, ISSN={0360-1323}, url={http://dx.doi.org/10.1016/s0360-1323(03)00135-5}, DOI={10.1016/s0360-1323(03)00135-5}, abstractNote={This paper presents a decision aid to assist contractors to estimate markup percentage to be included in their tenders, based on the Fuzzy neural network (FNN) approach. With the fuzzy logic inference system integrated inside, the FNN model provides users with a clear explanation to justify the rationality of the estimated markup output. Meanwhile, as every output of the FNN model is produced through the fuzzy inference rules, the results from the FNN model are in a reasonable and acceptable scale. By using this model, the difficulties in markup estimation due to its heuristic nature can be overcome.}, number={11}, journal={Building and Environment}, publisher={Elsevier BV}, author={Liu, Min and Ling, Yean Yng}, year={2003}, month={Nov}, pages={1303–1308} }
 @article{zhao_liu_xie_1998, title={Computer Simulation for Construction Project Investment Decision}, volume={30}, number={3}, journal={Journal of Xi’an University of Architecture and Technology}, author={Zhao, P. and Liu, M. and Xie, X.H.}, year={1998}, pages={290–293} }