Integrating critical chain project management with last planner system for linear scheduling of modular construction

Purpose The purpose of this paper is to present a new method for project tracking and control of integrated offsite and onsite activities in modular construction considering practical characteristics associated with this type of construction. Design/methodology/approach The design embraces building information modelling and integrates last planner system (LPS), linear scheduling method (LSM) and critical chain project management (CCPM) to develop tracking and control procedures for modular construction projects. The developed method accounts for constraints of resources continuity and uncertainties associated with activity duration. Features of proposed method are illustrated in a case example for tracking and control of modular projects. Findings Comparison between developed schedule and Monte Carlo simulation showed that baseline duration generated from simulation exceeds that produced by developed method by 12% and 10% for schedules with 50% and 90% confidence level, respectively. These percentages decrease based on interventions of members of project team in the LPS sessions. The case example results indicate that project is delayed 5% and experienced cost overrun of 2.5%. Originality/value Developed method integrated LPS, LSM and CCPM while using metrics for reliability assessment of linear schedules, namely, critical percent plan complete (PPCcr) and buffer index (BI). PPCcr and BI measure percentage of plan completion for critical activities and buffer consumption, respectively. The developed method provides a systematic procedure for forecasting look-ahead schedules using forecasting correction factor Δt and a newly developed tracking and control procedure that uses PPCcr and BI. Quantitative cost analysis is also provided to forecast and monitor project costs to prove the robustness of proposed framework.

A DSM-Based CCPM-MPL Representation Method for Project Scheduling under Rework Scenarios

Rework risks caused by information flow interactions have become a major challenge in project scheduling. To deal with this challenge, we propose a model integrating the critical chain project management method, design structure matrix method, and max-plus method. Our model uses a start-to-start relationship of activities instead of the traditional finish-to-start relationship, which also allows overlaps between activities. We improve the accuracy of the rework safety time in two ways: (1) the overall overlapping effect is taken into consideration when calculating the rework time of an activity arising from the information flow interaction of its multiple predecessors overlapped with it; (2) the rework time arising from activity overlaps, the first rework time, and the second rework time are calculated as components of the rework safety time in our model, while the last one is ignored in traditional methods. Furthermore, the accuracy of time buffers is improved based on the improved rework safety time. Finally, we design the max-plus method to generate project schedules and appropriately sized time buffers. The empirical results show that the project schedule generated by the proposed method has a higher on-time completion probability, as well as more appropriately sized project buffers.

Predicting Penetration of the Project Buffer Time of Critical Chain Project Management (CCPM) Using a Linear Programming Approach

Managing the disruptions in projects is a challenging task for project managers. In this respect, critical chain project management (CCPM) has been considered as a promising methodology in expediting projects. However, the effectiveness of this methodology is often lost in search of optimal use of project buffers to hedge against delays occurring in the critical chain. The more critical chain activity gets delayed, the greater is the likelihood of penetration of project buffer time. The resource constraints of critical chains have been considered as a major determinant of project buffer penetration. Although a project buffer is provided to protect the critical chain, to keep the CCPM project schedule competitive, it is the priority of the project manager to minimize the blatant consumption of project buffer time by multiple critical chain activities. Historically, resource constraints within the critical chain have been associated with penetration of project buffer time. The literature suggests that the productivity of resources deployed in the critical chain can predict the penetration of project buffer time. Based on the premise that delays are omnipresent and unavoidable but predictable, this research aims to consider the post-facto measures of delays instead of pre-facto measures. Pre-facto measures are resources productivity and resources availability while post-facto measures are the compensation paid by the client and the cost of liquidity damages incurred by the contractor. It is assumed that pre-facto measures are convertible into post-facto measures. A linear programming model is formulated and tested using the case of Botanical Garden Construction Project in Pune city. Sensitivity analysis revealed that the propensity of project buffer penetration on a critical chain varies with the compensation matrix. Varieties of scenario are developed and the optimal solution is validated with the case study.