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Business Improvement through Innovation in Construction Firms: The ‘Excellence’ Approach
Published in Ben Obinero Uwakweh, Issam A. Minkarah, 10th Symposium Construction Innovation and Global Competitiveness, 2002
Herbert S. Robinson, Patricia M. carrillo, Chimay J. Anumba, Ahmed M. Al-Ghassan
Programming methods for repetitive construction like the Linear Scheduling Method - LSM achieve work continuity for resources required to perform project activities taking place at a constant rate. LSM was first presented by Chrazanowsk in 1986, shaping identically to Line of Balance diagrams method, in which project activities are plotted as ascendant lines sloping upwards in an orthogonal system in which horizontal axis is a time scale and the number of units produced is represented in the vertical axis. The slope of each line means the production rate of the work teams allocated to the activity represented by that line. The project evolution in a given time instance can be easily analysed by drawing a vertical line in that position in the time scale and reading its interception in activity lines [Chrzanowsk, 1986] [8]. The advantages of this method when compared to traditional scheduling methods are as follows:
Quantifying the interruption impact of activity delays in non-serial repetitive construction projects
Published in Construction Management and Economics, 2020
To quantify the impact of unexpected activity delays that are often encountered during the construction phase, a number of the aforementioned scheduling models have been designed to identify the critical activities in serial and non-serial repetitive construction projects using two methods: controlling activity path, and rate float. The controlling activity path is defined by Harmelink and Rowings (1998, p. 263) as “the continuous path of longest duration through the project and defines the sequence of activities that must be completed as planned to finish the project within the overall planned duration”. This controlling activity path method was utilized by a number of models to identify critical activities that have an impact on the project duration in repetitive construction projects. For example, Harmelink and Rowings (1998) developed an algorithm based on linear scheduling method (LSM) to identify the controlling activity path in scheduling repetitive construction projects. The algorithm executes upward and downward pass calculations, similar to forward and backward passes in CPM calculations while maintaining the crew work continuity constraint. Harris and Ioannou (1998) utilized a similar method “repetitive scheduling method (RSM)” to calculate a sequence of controlling activity units for repetitive construction projects. This method provides more flexibility and is designed to consider construction projects with non-serial activities that have multi predecessor and successor activities and can be constructed sequentially and/or concurrently. Ammar and Elbeltagi (2001) developed a model based on the integration between LOB and the critical path method (CPM) that combine the benefits of both techniques to calculate the controlling activity path(s). Ammar (2013) created another mathematical model to improve the integration of the CPM/LOB framework that is capable of identifying the critical activities in a repetitive construction project and determining the total float for non-critical activities. Despite the contributions of these controlling activity path models, they are incapable of: (1) quantifying the impact of activity delays on the crew work continuity of successor activities; and (2) calculating other types of activity floats such as free and rate floats.
Dynamic schedule model and algorithm optimization method for linear engineering projects
Published in Engineering Optimization, 2023
Current methods for optimizing construction project scheduling, such as the critical path method and plan evaluation and review technique (Kim, Kang, and Hwang 2012), have limitations when it comes to planning repetitive construction projects (Bakry, Moselhi, and Zayed 2016; Su and Lucko 2016), particularly in linear engineering projects. These methods do not ensure the work continuity of construction activities or guarantee resource availability, and they fail to distinguish between the shape of activities or to express their exact location and speed of construction (Abdallah and Alshahri 2019; Ammar 2020; Monghasemi and Abdallah 2021). Moreover, they often require extensive repetitive work to model repetitive engineering projects, and when implemented in a dynamic construction environment, they lack the required efficiency (Abbasi, Taghizade, and Noorzai 2020). Linear methods, such as the line of balance (LOB) (Carr and Meyer 1974), linear scheduling method (LSM) (Johnston 1981) and repetitive scheduling method (Harris and Ioannou 1998), are commonly used to plan repetitive construction projects using a graphical representation of the process sequences performed by specific resources (e.g. crews) (Long and Ohsato 2009; Tomczak and Jaśkowski 2022). While LOB does not often account for unit differences in size (Tomczak and Jaśkowski 2022), LSM is the most efficient for linear projects as it shows relative positions between activities and highlights constraint relationships (Monghasemi and Abdallah 2021). In addition, linear projects can be efficiently planned using LSM as it helps to analyse scheduling in various construction scenarios, including forward and reverse construction of linear activities, as well as construction scenarios of line, bar and block activities, which are bounded by logical relationships between these different shapes of activities. However, comprehensive scheduling optimization studies for linear projects in such complete construction scenarios are lacking. Previous studies have shown that adjusting the activity resource allocation method (García-Nieves et al. 2019; Heravi and Moridi 2019), activity construction mode (García-Nieves et al. 2018, 2019; Monghasemi, Abdallah, and Clevenger 2020), construction direction (Biruk, Jaśkowski, and Czarnigowska 2017) and the order of activity construction (Zou, Wu, and Zhang 2021; Monghasemi and Abdallah 2021) can help in obtaining optimal plans in various scenarios. Therefore, adding multiple decision variables and improving construction constraint scenarios can increase the scheduling optimization model’s applicability in linear projects.