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Introduction Operations research, i.e. the application of scientific methodology to operational problems in the search for improved understanding and control, can be said to have started with the application of mathematical tools to military problems of supply bombing and strategy, during the Second World War. Post‐war these tools were applied to business problems, particularly production scheduling, inventory control and physical distribution because of the acute shortages of goods and the numerical aspects of these problems.

This paper aims to present a new method to circumvent the limitations of current schedule compression methods which reduce schedule crashing to the traditional time-cost trade-off analysis, where only cost is considered.

The schedule compression process is modeled as a multi-attributed decision making problem in which different factors contribute to priority setting for activity crashing. For this purpose, a modified format of the Multiple Binary Decision Method (MBDM) along with iterative crashing process is utilized. The method is implemented in MATLAB, with a dynamic link to MS-Project to facilitate the needed iterative rescheduling. To demonstrate the use of the developed method and to present its capabilities, a numerical example drawn from literature was analysed.

When considering cost only, the generated results were in good agreement with those generated using the harmony search (HS) method, particularly in capturing the project least-cost duration. However, when other factors in addition to cost were considered, as expected, different project least-cost and associated durations were obtained.

The developed method is not applicable, in its present formulation, to what is known as “linear projects” such as construction of highways and pipeline infrastructure projects which exhibit high degree of repetitive construction.

The novelty of the developed method lies in its capacity to allow for the consideration of a number of factors in addition to cost in performing schedule compression. Also through its allowance for possible variations in the relative importance of these factors at the individual activity level, it provides contractors with flexibility to consider a number of compression execution plans and identifies the most suitable plan. Accordingly, it enables the integration of contractors' judgment and experience in the crashing process and permits consideration of different project environments and constraints.

The purpose of this paper is to propose an integrated model for allocation and leveling of human resources in IT projects.

A single case study was conducted in a large company of IT outsourcing services, which were assessed the management of 14 projects. The survey was conducted through interviews with project managers, and digital files and internal documents of the organization related to these projects.

In the analysis, it was identified that the critical path is not identified in all projects, and even when this happens, resources are not allocated in the first tasks in that path. A committee controls the allocation of resources with the assessment of skills, but there is no control of all resource constraints.

The main limiting factors for this study are: use of data of one company in the IT industry, making it difficult to generalize the model for other sectors companies; it was noted during interviews that the project managers interviewed do not always know in detail all the company’s processes for allocation and resource leveling, due to the large number of processes and different management activities of these professionals.

A model and actions for this implementation was proposed, such as training for the use of the technique of critical path; allocation and leveling done simultaneously; decisions of the management committee based on information of availability, key skills, holidays, days off of human resources; development of a software tool that integrates this information, generating graphical interfaces that are not provided by project management software with the use of an allocation factor.

The characteristics of the proposed model, as well as the use of the allocation factor, can help managers to validate their allocation models and leveling of human resources in an integrated manner.

The study explains that the granularity of analysis of resource allocation increases by decomposition of the duration of each activity in fixed time segments. It is suggested to use the mathematical concept of the allocation factor (F_a).

This paper aims to exemplify the use of project management tools in the scheduling of aircraft maintenance activities. This process is known as maintenance, repair and overhaul and it has gained importance within the aeronautical sector due to its expected growth in the coming years; however, it also faces increasing competitiveness in its market. This fact gives rise to the need of acting in maintenance management and seeking lower costs while maintaining the quality of the service provided. The purpose of this paper is to propose the structuring of a procedure that aims to reduce the total maintenance time (downtime) and guarantee the delivery of the aircraft on time.

The paper, through a case study at a Brazilian aircraft maintenance center, used critical path method and critical chain project management, the latter being derived from the theory of constraints, with the purpose of analyzing resources systematically and synchronizing the activities in the precedence network.

As a result, it is shown that downtime can be reduced from 11 to 5 days and improvements are proposed to achieve greater market competitiveness.

This paper demonstrates the competitive advantage that resulted from the application of project management tools in the aircraft maintenance planning and execution.

Aircraft operators incur significant costs when an aircraft is taken out of service for maintenance. The purpose of this paper is to present a method for reducing time duration of aircraft maintenance checks using critical chain project management (CCPM) principle.

A case study of a typical heavy maintenance check performed on an Airbus 320 aircraft is undertaken for the analysis. The critical chain method is applied to develop a plan with a reduced duration and a survey and field observations to validate the findings have also been carried out as a part of this paper.

The paper compares the traditional project management method with CCPM in view of reducing the aircraft down time duration for maintenance. This paper repositions buffers and other techniques to shorten the chain path and a reduction in the total duration of the project by five days is achieved.

It is argued that the application of CCPM principle can reduce the duration of an aircraft maintenance check, but this paper is done in a single project situation focusing on project planning and execution. Therefore, additional study may be required to examine other issues.

Cost of the maintenance is second highest expenditure factor for an airline operator. Therefore, it is necessary to drive the maintenance cost down. The paper demonstrates that the duration of a maintenance check can be reduced by 8.9 per cent using the method suggested in this paper.

Compressing the schedule by using overlapping activities is a commonly adopted approach for accelerating projects. However, this approach might channel a variety of risks into the construction processes. Risks imply waste; still, evaluating the effects of using overlapping activities on schedule quality has been a looming gap in construction research. Therefore, this paper aims to study the quality of overlapping in terms of emerging waste and to demarcate the boundaries of the overlapping envelope.

This study presents a method for assessing the consequences of implementing overlapping activities in a schedule on two types of waste namely waiting time and variation gap. A critical path method (CPM) network including eleven activities is modeled stochastically where the durations of individual activities are sampled as beta-distributions. Using program evaluation and review technique (PERT) assumptions to calculate the schedule dates, the network is simulated for various amounts of overlapping and the corresponding waste is quantified each time.

Results show that not only the returns on overlapping are diminishing after a certain overlap percentage, but also waste in the production system increases. Particularly, results reveal that compressing the schedule leads to a decrease in variation gaps, but at the same time, it leads to a larger increase in waiting times, which creates more waste.

The presented study shows through simulation how overlapping activities affects productivity by identifying wastes. It shows that despite the apparent gains, overlaps should be used with caution, and while considering the side-effects of increased waste which introduces a need for increased managerial awareness.

The technique of Critical Path Analysis (CPA) and its applications are described. A simple example is used to illustrate the method. The use of CPA in the implementation of an automated lending system at Teesside Polytechnic Library is described.

This research presents a framework that allows project managers to predict the next critical paths (CP(s)) and to take extra care when planning and executing those activities that have the potential to cause changes in a project's current CP(s).

The method presented here is based on an assessment of each activity's contribution to the overall schedule variance, which involves assigning a probability distribution function to each activity duration in the project. A sensitivity analysis is also carried out, which forms the basis of identifying which activity most affects the project completion date and therefore will have the greatest effect in changing the CP.

The authors’ analysis reveals that the most appropriate probability density function (PDF) for the targeted project is the normal distribution. However, the aim of this work is not to determine the most suitable distribution for each activity but rather to study the effect of the activity distribution type on the CP prediction. The results show that the selection of the appropriate probability distribution is very important, since it can impact the CP prediction and estimated project completion date.

This research work proposes a delay analysis scheme which can help the project manager to predict the next CP and to improve performance by identifying which activity is the bottleneck. On the other hand, the simplicity arises from the fact that this method does not require any expensive machines or software to generate results.

The paper describes four methods of dealing with delay claims that effectively sum up the main approaches to this problem that have been offered in the literature. This is then followed by a description and discussion of results from a new survey aimed at finding out exactly how professionals in the UK construction industry approach these difficult issues. It appears that those who deal with delay claims in the UK are likely to use a critical path method network to do this and generally approve of a methodology that attempts to understand how well the contractor would have fared ‘but for’ the existence of employer‐responsible delays. There is less agreement about who should be said to own the float, but as is explained in the paper, it is possible for this matter to be dealt with by the insertion of a clause in the contract documents.

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.