Subcontractor Schedule Control Method

Trade coordination and claims documentation is a challenge on any project, particularly for specialty subcontractors. The writers introduce a schedule control method initiated by the subcontractor, which facilitates coordination and communication between a subcontractor and other project participants as well as documentation to the prime contractor. A case study illustrates the preparation of a trade-specific critical path method (CPM) schedule, which is updated on a regular basis. The writers also address the interrelationship between the CPM schedule, internal reporting, schedule of values, and labor tracking. It is difficult to ensure that all subcontractor-produced documentation is complementary, but it is well worth the effort when it comes to supporting a claim. Monthly schedule updates and narratives communicate the conflicts, issues, and schedule constraints the subcontractor experiences or anticipates on a project, thereby providing contractually required notice to the prime contractor during the project. This increases the likelihood of resolving issues during the project, while simultaneously protecting a subcontractor’s position if change order requests are denied or if back charges are levied prompting a subcontractor to enforce its rights, execute a claim, or proceed to litigation.     

On-Site Subcontractor Evaluation Method Based on Lean Principles and Partnering Practices

Subcontracting has greatly increased in the construction industry. It helps shift risk from the main contractor to the subcontractor and promotes specialization. Inadequate subcontracting management, however, may result in an adversarial relationship between main contractors and their subcontractors, uncoordinated on-site execution, and disappointing quality and schedule fulfillment. New subcontractor management methods and tools are being developed and tested as part of a collaborative research project led by the Catholic University Production Management Center with the participation of the Chilean Construction Chamber and several construction companies. The experience gained by testing prototype tools and methods on selected projects enabled us to develop an on-site evaluation method based on lean principles and partnering practices. This method allows main contractors to help subcontractors improve their performance by providing them with periodic feedback. It also supports subcontractor selection based on their previous performance, which helps foster collaborative relationships with those that consistently perform well. The results of the application of the method in two case studies are discussed.     

Modeling Interfirm Dependency: Game Theoretic Simulation to Examine the Holdup Problem in Project Networks

Subcontractor selection strategies used by contractors can significantly affect short-term project and long-term organizational success. Existing research on subcontractor selection strategy implicitly assumes that the evaluation of subcontractors depends on current conditions. We extend this perspective by integrating an agent-based simulation model with game theory to examine whether precontract partner selection strategies that do not consider subcontractor selection as a repeated game may lead to a version of the holdup problem. The holdup problem we investigate focuses on relationship-specific investments in learning after the introduction of an innovation or organizational change across a project network. A minimum total cost strategy may decelerate the rate of adaptation to an innovation or organizational change, thereby proving that the holdup problem can exist in project networks. The findings contribute to subcontractor selection strategy literature by simulating the impact of the holdup problem in project networks, distinguishing task interdependence as a moderating variable, and identifying that the minimum total cost strategy can be a suboptimal strategy for project networks adapting to systemic changes.     

Simplified Spreadsheet Solutions.?I: Subcontractor Information System

This paper presents a subcontractor information system (SIS) to support the estimating and project control functions of subcontractors and small∕medium-size contractors. For the proposed SIS to be simple and practical, it was developed in a spreadsheet program designed to maintain information related to resources and projects and to generate important business reports. Resource data are stored in six worksheets for labor, equipment, crews, material, subcontractors, and alternative methods of construction for various tasks. In addition, a separate worksheet is designed for each project to be used for estimating and control purposes. The latter worksheet allows the user to specify the work breakdown structure and optional methods for construction. As such, it represents a transparent estimating model that allows for quick what-if analysis regarding time and cost. In addition, the reporting worksheet provides information related to time, cost, and resource use at the individual and the multiproject levels. In a companion paper, the use of the SIS as basis for overall schedule optimization is described.     

Improved Subcontractor Selection Employing Partnering Principles

Despite the increasing extent of subcontracting in construction, the importance of subcontractor selection is frequently underestimated. While the subcontracting element needs more attention in contractor selection itself, subcontractor selection techniques themselves need considerable improvements. This paper examines how such techniques can beneficially draw from improved multicriteria contractor selection methodologies in general, and specifically from recent developments in client-contractor partnering. It is shown how partnering may be profitably extended further into the supply chain, i.e., into subcontractor selection. A European case study illustrates the development of a subcontractor selection process that incorporated partnering principles. Despite the longer and costlier selection process, it was found that subcontractor pricing levels were reduced by about 10% to account for anticipated efficiencies arising from the proposed partnering. Markedly better time and cost control was achieved on the pilot project. The relationships between all project participants were also found to have improved considerably. Such observations confirm the value (1) of expanding the partnering “envelope” to encompass subcontractors in general; and more specifically, (2) of assessing the potential for such extended partnering as an integral part of the subcontractor selection process.     

Concurrent Delays and Apportionment of Damages

This paper focuses on the subject of concurrent delay from a general contractor (GC)-subcontractor perspective. When there is a concurrent delay by multiple subcontractors, or between the GC and other subcontractor(s), there has not been a uniform approach as to how the liquidated damages are apportioned. Previous research seems to ignore this issue. This paper first reviews some relevant court cases. Using a warehouse project as a case study, it then examines different practices that the GC could take in apportioning damages of concurrent delays to both himself/herself as well as to the responsible subcontractors. Results are very inconsistent between and within the apportionment practices. This supports an alternative hypothesis that apportionment is an important issue. Practitioners should specify which apportionment practice will be used and under what circumstances it will be applied in their subcontracts. Researchers may develop a more consistent and reliable approach for this type of apportionment.     

D-SUB: Decision Support System for Subcontracting Construction Works

Letting work to subcontractors is a very common practice in construction industry. Subcontractors help contractors overcome problems including the need of special expertise, shortage in resources, and limitation in finances. The decision to subcontract involves designating work items to be subcontracted and making assignments to subcontractors. Generally, work assignments to subcontractors can be for the total quantity of a work item or a proportion thereof. This paper presents a decision support system that makes assignments to subcontractors of the work items designated for subcontracting. Moreover, the system calculates and plots the overdraft profile based on the financial terms of the contract and project schedule. The ultimate goal of the system is to make work assignments to subcontractors under constraints economical and predict the expected profit at the end of the project. The system encompasses four basic components including project data, linear programming module, sensitivity analysis module, and financial analysis module. The sensitivity analysis adds strength and flexibility to the system by allowing the user to experiment with different scenarios. Finally, the developed system that represents a structured method for making subcontracting decisions is demonstrated through an illustrative example project.     

Methodology for Integrated Risk Management and Proactive Scheduling of Construction Projects

An integrated methodology is developed for planning construction projects under uncertainty. The methodology relies on a computer supported risk management system that allows for the identification, analysis, and quantification of the major risk factors and the derivation of their probability of occurrence and their impact on the duration of the project activities. Using project management estimates of the marginal cost of activity starting time disruptions, a heuristic procedure is used to develop a stable proactive baseline schedule that is sufficiently protected against the anticipated disruptions that may occur during project execution and that exhibits acceptable makespan performance. We illustrate the application of the methodology on a real life construction project and demonstrate that our proactive scheduler generates baseline schedules that outperform the schedules generated by commercial software packages in terms of robustness and timely project completion probability.     

Accuracy of Highway Contractor’s Schedules

Contractors are required by the Michigan Department of Transportation (MDOT) to submit a progress schedule identifying the controlling path of activities for a construction project. During the 2000 construction season, MDOT allowed contractors to submit a progress schedule with overlapping or concurrent controlling operations. Prior to this, only one activity at a time could be controlling on the progress schedule. This paper reports on the results of a research project where the focus was to examine the accuracy of the progress schedules, which only list controlling items. Eight construction projects were studied and a determination of progress schedule accuracy was made. This was done to determine if there was an increase in accuracy of the schedules when concurrent controlling operations were used. Included in the eight projects were four without concurrent controlling activities and four with concurrent controlling activities. A comparison based upon similar projects with and without concurrent activities was made. Additionally, 22 projects were analyzed, all without concurrent controlling activities, to determine the accuracy of progress schedules for two types of projects. The comparison revealed that, in three of the four cases, the accuracy of progress schedules increased with the allowance of concurrent controlling activities. The 22 projects revealed that the accuracy of progress schedules varied considerably. It was also determined that contractors overestimated the duration of activities included in progress schedules.     

Exact Algorithm for Solving Project Scheduling Problems under Multiple Resource Constraints

This paper presents a new algorithm, called the enumerative branch-and-cut procedure (EBAC), for minimizing the total project duration of a construction project under multiple resource constraints based on an enumeration tree. The EBAC generates new branches to the tree corresponding to “better” feasible alternatives. It starts with all of the feasible schedule alternatives as the trial schedule alternatives at any node. The trial schedule alternatives are then evaluated to determine whether they are “worse” than any existing partial schedules in the tree by using the presented cut rules, and a worse alternative will be eliminated from the enumeration tree. In other words, the tree will contain only better feasible schedules. The presented algorithm has been coded in the VB6.0 language on a personal computer. It has been tested with the 110 scheduling problems, which have been widely used for validating a variety of schedule algorithms over the last 20?years. The EBAC can obtain the shortest project durations for all of the 110 problems.     

Measuring Safety Climate of a Construction Company

Safety climate can benefit contractors, specialty contractors, and owners of industries by providing them with the knowledge of attitudes and perceptions that can help to consistently achieve better safety performance. The objective of this research was to determine safety climate that would enhance safety culture and positively impact perceived safety performance on construction projects. A safety climate questionnaire survey was conducted on the construction sites of a leading construction company and its subcontractors in Hong Kong. Approximately, 1,500 hard copy questionnaires were distributed and the response rate was excellent, resulting in 1,120 valid questionnaires being collected from 22 construction projects. By means of factor analysis, two underlying safety climate factors were extracted, accounting for 43.9% of the total variance. Multiple regression analysis confirmed that these climate factors, “management commitment and employee involvement” and “inappropriate safety procedure and work practices” were significant predictors of workers’ perceptions of safety performance. The findings indicated that the relationship between perceived safety performance and “inappropriate safety procedure and work practices” was inversely correlated. The results suggest that safety climate can be used as an effective measure of assessing and improving site safety for projects under construction. The findings of this study and the methodology might be useful for research at other construction sites in other regions and countries. This work provides useful information for project managers and safety practitioners who desire to improve safety climate and safety performance on construction sites.     

Divergence or Congruence? A Path Model of Rework for Building and Civil Engineering Projects

Rework has been identified as a major contributor to cost and schedule overrun in construction projects. Previous studies that have examined rework are based on a limited data sets and thus eschew generalizations being made about the key determinants. Using data from 260 completed building (n = 147) and civil engineering (n = 113) projects, path analysis is used to develop a structural model of the most significant causes of rework. The model revealed that the paths of client-directed changes, site management and subcontractors, and project communication were statistically significant contributors to rework costs. The analysis confirmed that the lack of attention to quality management resulted in higher rework costs being incurred in the projects sampled. The analysis also revealed that there were no significant differences between building and civil engineering projects in terms of the direct and indirect cost of rework experienced, and the effectiveness of the project management practices implemented. Considering the findings, it is suggested that generic strategies for reducing the incidence rework in construction and civil engineering projects can be developed.     

Whole Life Performance Assessment: Critical Success Factors

Whole life costing (WLC) has become the best practice in construction procurement and it is likely to be a major issue in predicting whole life costs of a construction project accurately. However, different expectations from different organizations throughout a project’s life and the lack of data, monitoring targets, and long-term interest for many key players are obstacles to be overcome if WLC is to be implemented. A questionnaire survey was undertaken to investigate a set of ten common factors and 188 individual factors. These were grouped into eight critical categories (project scope, time, cost, quality, contract/administration, human resource, risk, and health and safety) by project phase, as perceived by the clients, contractors and subcontractors in order to identify critical success factors for whole life performance assessment (WLPA). Using a relative importance index, the top ten critical factors for each category, from the perspective of project participants, were analyzed and ranked. Their agreement on those categories and factors were analyzed using Spearman’s rank correlation. All participants identify “Type of Project” as the most common critical factor in the eight categories for WLPA. Using the relative index ranking technique and weighted average methods, it was found that the most critical individual factors in each category were: “clarity of contract” (scope); “fixed construction period” (time); “precise project budget estimate” (cost); “material quality” (quality); “mutual/trusting relationships” (contract/administration); “leadership/team management” (human resource); and “management of work safety on site” (health and safety). There was relatively a high agreement on these categories among all participants. Obviously, with 80 critical factors of WLPA, there is a stronger positive relationship between client and contactor rather than contractor and subcontractor, client and subcontractor. Putting these critical factors into a criteria matrix can facilitate an initial framework of WLPA in order to aid decision making in the public sector in South Korea for evaluation/selection process of a construction project at the bid stage.     

Construction Delay Computation Method

Delay is one of the most common problems in the construction industry. This paper presents a method for computing activity delays and assessing their contributions to project delay. The method consists of a set of equations, which can be easily coded into a computer program that allows speedy access to project delay information and activity contributions. The proposed method contrasts the as-planned and as-built schedules. It is not based on critical path analyses; therefore, it does not require the calculation or updating of the critical path, and it is even not necessary to update the as-planned schedule, as required by the traditional delay analysis methods. The results calculated from the proposed method include various variations of activity schedules and their contributions (in days) to the overall project delay. They provide an objective baseline for determining responsibilities of delays. The method can be integrated into any delay analysis system to further improve and automate the construction delay analysis process. Practical examples are used to illustrate the computation mechanism.     

Role of the Fabricator in Labor Productivity

This paper describes the results of three case studies in which the subcontractor-fabricator relations had a significant negative effect on labor productivity of the subcontractor. Late vendor deliveries, fabrication or construction errors, and out-of-sequence deliveries plagued each of the three projects. On two projects, there were work stoppages because there were no materials. Unsequenced deliveries caused unnecessary crane movements and rework. On the third project, the output of the fabrication shop was not compatible with the output of the erection crew. The baseline productivity was calculated, and the loss of labor efficiency in each case was estimated to be 16.6, 28.4, and 56.8%. These percentages were compared with similar percentages calculated from other published articles that described inefficient site storage conditions and delivery methods. The labor inefficiencies caused by material management range from a low of 5.4% to a high of 56.8%. The schedule slippage on the three case study projects was estimated to be between 50 and 129%.     

Finance-Based Scheduling of Construction Projects Using Integer Programming

Construction scheduling is the process of devising schemes for sequencing activities. A realistic schedule fulfills the real concerns of users, thus minimizing the chances of schedule failure. The minimization of total project duration has been the concept underlying critical-path method/program evaluation and review technique (CPM/PERT) schedules. Subsequently, techniques including resource management and time-cost trade-off analysis were developed to customize CPM/PERT schedules in order to fulfill users’ concerns regarding project resources, cost, and time. However, financing construction activities throughout the course of the project is another crucial concern that must be properly treated otherwise, nonrealistic schedules are to be anticipated. Unless contractors manage to procure adequate cash to keep construction work running according to schedule, the pace of work will definitely be relaxed. Therefore, always keeping scheduled activities in balance with available cash is a potential contribution to producing realistic schedules. This paper introduces an integer-programming finance-based scheduling method to produce financially feasible schedules that balance the financing requirements of activities at any period with the cash available during that same period. The proposed method offers twofold benefits of minimizing total project duration and fulfilling finance availability constraints.     

Importance of Capacity Constraints to Construction Cost and Schedule

This paper makes a practice-based critique of the assumptions behind network planning methods from the perspective of subcontractors and suppliers. In the context of a case example, the time-cost trade-off and its resource-oriented extensions are critiqued as being incapable of representing the capacity costs and constraints of subcontractors and suppliers. These methods are also critiqued as being incapable of representing the effects of site conditions on productivity, which in turn affects the capacity choices of subcontractors. Restricting the focus to the general building industry, case findings from 15 subcontractors and suppliers are presented. The case research indicates that capacity constraints systematically affect subcontractors and suppliers and that site conditions affect the productivity of subcontractors. Moreover, it is found that these firms consistently take action to mitigate the impact of capacity constraints and site conditions on cost. This second finding suggests that not only do network planning methods fail to account for the costs of capacity constraints and site conditions, but also that the schedules generated by network techniques will be inaccurate. Hence, the research implies that much of the current basis of construction costing and control is inadequate to its task, and that new methods must be developed that more realistically represent the needs of construction subcontractors and suppliers.     

Integrating Efficient Resource Optimization and Linear Schedule Analysis with Singularity Functions

Resources perform or enable physical operations and thus are vital on construction projects, yet are subject to various constraints. Their use within a project schedule must therefore be carefully planned. A major objective is optimizing when they are active within the float of noncritical activities to avoid disruptive and costly fluctuations. This paper builds on analyzing criticality of linear schedules with the unique singularity functions. The new approach keeps resources intact and derives one flexible equation for the complete resource profile of a schedule, including any timing or resource rate changes. Another equation models its first moment of area to minimize the objective function toward a level profile. A genetic algorithm is suitable for an iterative optimization. The parameters of its chromosomes are recombined evolutionarily and can model any permutation. Analyzing a road project illustrates how singularity functions integrate resource optimization with its linear schedule and facilitate a subsequent optimization.     

Effect of Delivery Systems on Collaborative Negotiations for Large-Scale Infrastructure Projects

In large-scale projects, collaboration is an essential key for the success of projects. Since different participants from different organizations try to work together in projects, competitive stresses exist in their relationships and as a result, disputes or conflicts may inevitably occur. This paper builds on Pea-Mora and Wang's collaborative negotiation methodology for facilitating∕mediating the negotiation process of conflicts. In order for that collaborative negotiation methodology to be more detailed for its implementation, it needs to account for the effect of project structures and delivery methods on the negotiation processes in large-scale projects. Because contracts define the temporary formal and informal relationships among the different parties in a project and subsequently, they define the framework of the negotiations of conflicts within that project, different delivery systems may be more or less effective in terms of conflict resolution. In this research, to study the effect of delivery system on negotiation of conflicts, first, several different project structures and delivery systems are studied in order to identify participants' roles, responsibilities, and relationships. Second, potential conflicts in relationships among project participants are examined to show that each delivery system has typical or pattern behavior that may affect the interrelationship among groups on negotiations. These patterns or characteristics of the groups and their relationship make possible to evaluate quantitatively and qualitatively the advantage or disadvantage of each delivery system in terms of conflict avoidance or dispute resolution. Then, indexes of negotiation effectiveness for each delivery system are developed in order to quantify the advantage of implementing the collaborative negotiation methodology in a large-scale project within a particular delivery system.     

Case Study to Identify Barriers and Incentives to Implementing an Engineering Control for Concrete Grinding Dust

Research has indicated that respirable crystalline silica dust exposure is a serious health hazard in the construction industry. One source of this hazard is the dust generated by drilling, sawing, chipping, and grinding concrete. There are several options for controlling this hazard, one of which is the use of local exhaust ventilation (LEV) directly attached to the cutting tool. Implementing an engineering control presents a challenge on the construction work site where it is often difficult to determine who will take the initiative for introducing an innovative strategy. This study examines the implementation of an LEV system on an overhead grinder illustrating the roles that various members of the construction team played. The results of the case study found that key factors that affected implementation were: (1) a cooperative relationship between individuals employed by the general contractor and the concrete subcontractor; (2) the effect of high airborne dust levels on scheduling the work of other subcontractors; (3) the public relations effects of high dust levels in a downtown area; and (4) the concrete subcontractor perceived benefits that exceeded the short-term cost of the intervention.