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The line of balance (LOB) method is a suitable scheduling technique that managers can use to support lean planning efforts for projects composed of repetitive activities such as high-rise building construction. Like any other method, LOB has certain disadvantages that create a set of practical limitations in its application. An LOB schedule gives insights about how continuous and synchronized single resources are scheduled and how uniform these resources are distributed over the project duration. However, these three characteristics have to be visually checked, which makes the evaluation and the comparison of different schedule alternatives difficult. To overcome this problem, the purpose of this paper is to present a quantitative method to calculate quality degrees for the continuity, the synchronization and the uniformity of an LOB schedule that can be applied to assess an LOB schedule globally.

The paper introduces a set of global indicators, termed quality degrees, which allow for a quick quantitative evaluation of LOB schedules at the global level. These quality degrees are quantitative indicators for the: degree of continuity, degree of synchronization and degree of uniformity within a specific LOB alternative. A mathematical model was developed to calculate the quality degrees for LOB schedules. This model was validated using a well-known case study extracted from literature, and its practical implementation was exemplified on two real Romanian projects.

The paper illustrates this contribution using two case studies that confirm that the proposed method can be used to evaluate different schedule alternatives. In particular, the paper shows that quality indicators can be used to analyze and control interdependencies between cost and time.

The main limitation of the proposed method is that it cannot indicate the desired level of continuity, synchronization or uniformity to be achieved. Further studies need to explore this possibility, as well the relationship between indicators.

The presented quality indicators contribute to existing LOB methods as they allow for the quick analysis and assessment of schedules without an in-depth visual analysis.

The paper proposes an innovative method, mathematically formulated, to quantitatively assess the quality aspects of continuity, synchronization and uniformity for LOB schedules.

The purpose of this paper is to answer the question of how continuity and change coexist in the work of institutional actors who can combine maintenance, disruption and/or creation. Past studies mention this coexistence without an explanation.

The paper develops a perspective through literature review.

Institutional actors are both socialized into the norm-oriented space of continuity and maintenance through their reciprocal relations and associated social knowledge and roles and disciplined into the goal-oriented space of change and disruption/creation through their power relations and associated expert discourse and subject positions. Their institutional existence indicates a particular combination of reciprocity and power and thus their work includes changing degrees of maintenance, disruption and creation, depending on the nature of this combination.

The paper points out research directions on the relational conditions of the actors, which facilitate or constrain their work toward institutional continuity or change.

Organizations whose concern is to continue the existing practices in a stable environment should emphasize reciprocal relations whereas organizations whose concern is to change those practices for more effectiveness in a dynamic environment should emphasize power relations. Also, too much emphasis on either relations leads to inflexibility or instability.

The paper provides an explanation on the sources of coexistence of continuity and change in institutional work. It also contributes to the discussions on contingency of institutions, resistance productive of institutional change, reflexivity of institutional actors and intersubjective construction of institutional work.

The study aims to test, measure and quantify the impacts of lean construction and BIM implementation on flow in construction projects.

Detailed control data from a set of 18 high-rise residential construction projects executed between years 2011 and 2020 were analyzed using the construction flow index (CFI), a measure of workflow quality. Seven comparable projects with a diverse range of LPS, BIM, VDC and 5S implementation were selected to compare the impacts of these innovations on flow.

Implementing BIM in the big room and applying the last planner system and other lean construction techniques increased the CFI from 4.31 to 8.12 (on a 10-point scale). Avoiding trades crossing one another's paths between tasks was the most significant aspect of improved flow. Moreover, the benefits of implementing lean practices with BIM or VDC were found to be measurably greater than when these approaches were implemented separately.

The primary limitation of the study is that the degree of confidence in the results is limited by the nature of the case study approach. Although 18 is a respectable number of case study projects, it cannot offer the degree of confidence that a broader, representative sample of projects could. Similarly, the case studies are all drawn from the same construction context (residential apartments) and the same geographic region, which necessarily limits confidence concerning the degree to which the findings can be generalized.

The research is the first of its kind to quantitatively assess the impacts of BIM and lean construction on flow. Use of the CFI to quantify flow quality also highlights the potential value of CFI in providing project managers and planners a clear view of the smoothness or irregularity of flow and of differences between subcontractors' production rates.

Arguing against a concept of learning as only a formal process occurring in explicitly educational settings like schools, the paper proposes a conception of the workplace as a learning environment focusing on the interaction between the affordances and constraints of the social setting, on the one hand, and the agency and biography of the individual participant, on the other. Workplaces impose certain expectations and norms in the interest of their own continuity and survival, and in the interest of certain participants; but learners also choose to act in certain ways dependent on their own preferences and goals. Thus, the workplace as a learning environment must be understood as a complex negotiation about knowledge‐use, roles and processes – essentially as a question of the learner's participation in situated work activities.

The aim of this study is to measure the impact of the factors affecting construction labor productivity by focusing on different types of construction works during and after the COVID-19 pandemic in Turkey, as well as discuss solutions and immediate actions.

This research was conducted in two steps. First, a quantitative survey was carried out to determine the dimension of factors negatively affecting construction labor productivity and the loss rate of different construction works from the employee perspective. The factors were identified through a literature review. The crucial relationships were highlighted as a result of a statistical analysis. Second, a survey was performed to determine the loss rate through a comparison of man-hour values before and after the beginning of the pandemic from the employer perspective. After an analysis and comparison of the results, semi-structured interviews were performed to discuss all findings and discover ways to mitigate the impacts of COVID-19 on construction labor productivity.

The results of the study clearly show that construction labor productivity was deeply affected by the coronavirus disease (COVID-19) pandemic. Legal obligations, such as social distancing, wearing masks, and limitations on the number of workers, have been major drivers for lower labor productivity. Such obligations have a profound impact on interior construction works, especially based on teamwork. Concerning employer and labor-related factors, problems with getting payments on time, loss of income, and financial hardships are the leading factors resulting in decreased worker performance. Excavation, insulation, and plastering works were determined as the most affected construction works under the influence of the COVID-19 pandemic.

The quantitative portion of this study is limited to a sample of respondents in the Turkish construction industry. Further research is necessary to provide an in-depth review into construction labor productivity in other countries with a larger respondent sample. Another limitation is sourced by the dynamics of the COVID-19 pandemic, which may turn out that some findings are outdated. Despite these limitations, the insights from this study may enable employers to understand the major drivers and deep impacts of labor productivity loss by uncovering the main vulnerabilities during the pandemic. Recommended measures may also help policy-makers and stakeholders in the construction industry take necessary and immediate actions to ensure better construction labor productivity.

The study may contribute to a better understanding of a pandemic's impact on labor productivity by focusing on both employee and employer perspectives, especially in developing countries. The paper may help employers decide which priority measures are required for each construction work separately. The study is crucial not only for minimizing the negative effects of the COVID-19 outbreak on labor productivity but also for preparing for the post-pandemic era.

In repetitive projects, repetition offers more possibilities for activity scheduling at the sub-activity level. However, existing resource-constrained repetitive scheduling problem (RCRSP) models assume that there is only one sequence in performing the sub-activities of each activity, resulting in an inefficient resource allocation. This paper proposes a novel repetitive scheduling model for solving RCRSP with soft logic.

In this paper, a constraint programming model is developed to solve the RCRSP using soft logic, aiming at the possible relationship between parallel execution, orderly execution or partial parallel and partial orderly execution of different sub activities of the same activity in repetitive projects. The proposed model integrated crew assignment strategies and allowed continuous or fragmented execution.

When solving RCRSP, it is necessary to take soft logic into account. If managers only consider the fixed logic between sub-activities, they are likely to develop a delayed schedule. The practicality and effectiveness of the model were verified by a housing project based on eight different scenarios. The results showed that the constraint programming model outperformed its equivalent mathematical model in terms of solving speed and solution quality.

Available studies assume a fixed logic between sub-activities of the same activity in repetitive projects. However, there is no fixed construction sequence between sub-activities for some projects, e.g. hotel renovation projects. Therefore, this paper considers the soft logic relationship between sub-activities and investigates how to make the objective optimal without violating the resource availability constraint.

The purpose of this research is to develop a time-cost optimization model to schedule repetitive projects while considering limited resource availability.

The model is based on the constraint programming (CP) framework; it integrates multiple scheduling characteristics of repetitive activities such as continuous or fragmented execution, atypical activities and coexistence of different modes in an activity. To improve project performance while avoiding inefficient hiring and firing conditions, the strategy of bidirectional acceleration is presented and implemented, which requires keeping regular changes in the execution modes between successive subactivities in the same activity.

Two case studies involving a real residential building construction project and a hotel refurbishing project are used to demonstrate the application of the proposed model based on four different scenarios. The results show that (1) the CP model has great advantages in terms of solving speed and solution quality than its equivalent mathematical model, (2) higher project performance can be obtained compared to using previously developed models and (3) the model can be easily replicated or even modified to enable multicrew implementation.

The original contribution of this research is presenting a novel CP-based repetitive scheduling optimization model to solve the multimode resource-constrained time-cost tradeoff problem of repetitive projects. The model has the capability of minimizing the project total cost that is composed of direct costs, indirect costs, early completion incentives and late completion penalties.

This study aims to apply some concepts of actuarial statistics to the authorship of Iranian ISI papers in the field of chemistry based on Price’s model. The study determines scientific birth rate, death rate, infant mortality rate, natural increase rate and life expectancy.

Price maintained that authors in each given period in any field fall into four categories including newcomers, transients, continuants and terminators. He suggested that actuarial statistics could be applied to authorship to calculate death rate and birth rate in scientific fields. A total 25,573 papers written by 59,661 Iranian chemistry authors between 1973 and 2012 were downloaded from Web of Science (WoS) and were subjected to statistical analysis.

The average birth rate was 66.7 per cent, the average death rate was 19.4 per cent, infant mortality rate was 51.2 per cent, average natural increase was 47.3 per cent, the average life expectancy was 1.98 years and the longest scientific age was 22 years. The results show that although a large number of people start their scientific activity, the number of those who terminate their activity in the same year as they start (infant mortality rate) is also large and little continuity exists in the publishing activities of Iranian chemists.

The findings have implications for the planning of human resources in science. They could help maintain a stable scientific labor force and decide for instance whether a larger number of scientists should be trained and hired, or the barriers should be removed so the existing scientists can work for more years. The limitation is that the study is restricted to ISI articles, although they are not the only kind of scientific output.

This is the first study of its kind on Iranian scientific output. It shows that the overall labor force in the field of chemistry in Iran was not satisfactory, as the majority of authors in each period are transients. There is a need for better planning for the labor force.

Since the early 1960s, there have been different techniques to schedule linear projects, but for the most part, these have been overshadowed by the critical path method (CPM). Recently, there has been renewed interest in linear scheduling and in adapting some of the CPM techniques to linear scheduling. This necessitates a review of the research in the area of linear scheduling. The present paper provides an overview of linear scheduling, discusses the different approaches that have been used and expresses new avenues for research in the area of resource levelling of linear schedules.

The authors were motivated to overcome some of the limitations and shortcomings of the existing software systems for management of construction projects. The result is a new generation software system for CONstruction Scheduling, Cost Optimization, and Change Order Management, which is called CONSCOM. CONSCOM uses the recently patented Neural Dynamics model of Adeli and Park as its computational engine for construction cost optimization and advanced software engineering and object‐oriented programming techniques such as framework and pattern. This paper presents some of its recent and innovative capabilities and features. CONSCOM includes an Integrated Management Environment (IME) as its user interface for the effective control and management of construction projects. An example of a highway construction project is presented to demonstrate the unique modelling capabilities of CONSCOM that cannot be modelled by Critical Path Method (CPM) or CPM‐like networks.