Characteristics and classification of the annualised workings hours planning problems

Annualising working hours (i.e., the possibility of irregularly distributing throughout the year the total amount of the employees working hours) is one of the means to face the seasonal nature of the demand. Annualising working hours provides much flexibility to the production system (which is one of the main principles of lean production), so the company is allowed to plan the staff working time more efficiently. However, doing irregular working weeks implies a worsening of the working conditions that could be compensated by reducing the workers annual working time. On the other hand, conditions are provided in order to avoid an excessive workers’ overburden in long periods of strong demand. This paper introduces annualised hours (AH) as a mean to achieve production flexibility and proposes a classification scheme of the annualised working hours planning problems that arise in services and in manufacturing, as well as an approach for solving them by using mixed and integer linear programming and assessing the benefits of introducing AH.Peer Reviewe

Annualised Hours: A Real Flexibility Tool

Annualising working hours (AH) is a mean to face the seasonal nature of the demand. AH provides much flexibility to the production system, so the company is allowed to plan the staff working time more efficiently. However, the introduction of AH entails new optimisation problems to solve, as is the working time planning problem. These problems should be solved in an efficient way so AH could be a real and operative flexibility tool. Mixed and integer linear programming has been shown as a very effective approach in the resolution of some real and artificial generated AH problems.Peer Reviewe

Using a MILP model to establish a framework for an annualised hours agreement

Production flexibility is essential for industrial companies that have to deal with seasonal demand. Human resources are one of the main sources of flexibility. Annualising working hours (i.e., the possibility of irregularly distributing the total number of working hours over the course of a year) is a tool that provides flexibility to organizations; it enables a firm to adapt production capacity to fluctuations in demand. However, it can imply a worsening of the staff’s working conditions. To take the human aspect into account, the planning and scheduling of working time should comply with constraints derived from the law or from a collective bargaining agreement. Furthermore, new and more difficult working-time planning and scheduling problems are arising. This paper proposes a mixed-integer linear program model to solve the problem of planning the production and the working hours of a human team that operates in a multi-product process. Solving the model for different settings provides the essential quantitative information to negotiate the best conditions of the annualised hours system (the elements to establish the trade-off between weekly flexibility and economic or working-time reduction compensation can be obtained). The results achieved in a computational experiment were very satisfactory.Peer Reviewe

Cost-efficient staffing under annualized hours

We study how flexibility in workforce capacity can be used to efficiently match capacity and demand. Flexibility in workforce capacity is introduced by the annualized hours regime. Annualized hours allow organizations to measure working time per year, instead of per month or per week. An additional source of flexibility is hiring employees with different contract types, like full-time, part-time, and min-max, and by hiring subcontractors. We propose a mathematical programming formulation that incorporates annualized hours and shows to be very flexible with regard to modeling various contract types. The objective of our model is to minimize salary cost, thereby covering workforce demand, and using annualized hours. Our model is able to address various business questions regarding tactical workforce planning problems, e.g., with regard to annualized hours, subcontracting, and vacation planning. In a case study for a Dutch hospital two of these business questions are addressed, and we demonstrate that applying annualized hours potentially saves up to 5.2% in personnel wages annually

Determining the most appropriate set of weekly working hours for planning annualised working time

Annualised hours—the irregular distribution of working hours over a year—allow companies to adapt capacity to demand, thus reducing overtime, the number of temporary workers and inventory costs. To avoid a significant deterioration in working conditions, many laws and agreements constrain the distribution of working time. One way of doing this is by specifying a finite set of weekly working hours and bounding the annual number of weeks of each type. Although this set has a great impact on the solution, it is usually agreed without taking all the available data (demand, costs, etc.) into consideration. This paper proposes a method for selecting the most appropriate set of weekly working hours and establishing an annual plan or working time for each worker as a way of optimising service level. To this end, two mathematical programming models are proposed. By means of a computational experiment, it is shown that one of the models can be solved in short computing times and can thus be used as a decision-making tool.Peer Reviewe

Enabling flexibility through strategic management of complex engineering systems

”Flexibility is a highly desired attribute of many systems operating in changing or uncertain conditions. It is a common theme in complex systems to identify where flexibility is generated within a system and how to model the processes needed to maintain and sustain flexibility. The key research question that is addressed is: how do we create a new definition of workforce flexibility within a human-technology-artificial intelligence environment? Workforce flexibility is the management of organizational labor capacities and capabilities in operational environments using a broad and diffuse set of tools and approaches to mitigate system imbalances caused by uncertainties or changes. We establish a baseline reference for managers to use in choosing flexibility methods for specific applications and we determine the scope and effectiveness of these traditional flexibility methods. The unique contributions of this research are: a) a new definition of workforce flexibility for a human-technology work environment versus traditional definitions; b) using a system of systems (SoS) approach to create and sustain that flexibility; and c) applying a coordinating strategy for optimal workforce flexibility within the human- technology framework. This dissertation research fills the gap of how we can model flexibility using SoS engineering to show where flexibility emerges and what strategies a manager can use to manage flexibility within this technology construct”--Abstract, page iii

Manpower Planning with Annualized Hours Flexibility: a Fuzzy Mathematical Programming Approach

We have considered the problem of Annualized Hours (AH) in workforce management. AH is a method of distributing working hours with respect to the demand over a year. In this paper the basic manpower planning problem with AH flexibility is formulated as a fuzzy mathematical programming problem with flexible constraints. Three models of AH planning problem under conditions of fuzzy uncertainty are presented using different aggregation operators. These fuzzy models softens the rigidity of deterministic model by relaxing some of the constraints using flexible programming. Finally, an illustration is given with a computational experiment performed on realistic scale case problem of an automobile company to demonstrate and analyze the effectiveness of the fuzzy approach over deterministic model

Gestión de los horarios de trabajo en presencia de cláusulas de flexibilidad pasiva.

La flexibilidad pasiva permite adaptar de forma eficiente y económica la capacidad de producción a las fluctuaciones de la demanda, pero genera una gran dificultad en la gestión de los horarios individuales así como la no aceptación de este tipo de sistemas por parte de los trabajadores. Se presentan dos modalidades de flexibilidad (jornada anualizada y cuentas de horas) y se muestra como, mediante herramientas de gestión de horarios adecuadas, es posible sacar el máximo partido de la flexibilidad manteniendo el respeto por las condiciones de los trabajadores.Peer Reviewe

Analysis and implementation of volume flexibility in manufacturing plans

Manufacturing flexibility - the ability to change or respond quickly has been heralded as a major competitive weapon for manufacturing organisations operating in turbulent markets and markets characterised by fierce competition and rapid developments in technology. It is also important for the achievement of new management paradigms such as time-based competition, lean production, business process re-engineering and mass customisation. However, many issues on the concept of manufacturing flexibility such as, the clarification of why flexibility is needed, when it is needed, and how it can be implemented in manufacturing organisations have not been sufficiently addressed and resolved in the literature. This research project has been carried out to resolve some of these issues by focusing on one aspect of manufacturing flexibility - volume flexibility. The research design, which was developed to address the research issues, comprised the use of both quantitative and qualitative research methods. The quantitative research method is an exploratory mail survey of UK manufacturing plants in all the major industrial classifications. The survey was used to obtain broad patterns and evidence concerning the conditions that drive manufacturing plants to require volume flexibility and also to identify the mechanisms which manufacturing plants employ to achieve volume flexibility. The qualitative research method is an explanatory case-based research. Manufacturing plants in each sector that responded to the survey and provided rich and contrasting information about the issues being investigated were selected for the case study research. The case study research was used to confirm the survey results (triangulation) and more importantly to explain the trends and patterns observed in the survey analysis. The research concluded that high variability in demand levels is a major driver of volume flexibility and that it is generic in nature. Other drivers of volume flexibility were also identified. However, the applicability of these drivers to manufacturing plants was found to be independent of the sector to which the plants belong but on other specific characteristics of the plants. Mechanisms being employed to achieve volume flexibility in UK manufacturing plants were identified and referred to as enablers of volume flexibility. These enablers are not sector dependent but they do depend on specific market conditions, and their perceived costs and benefits. Substitute and complementary enablers were identified. Substitute enablers can be used to replace other enablers to achieve volume flexibility and complementary enablers aid other enablers in achieving volume flexibility. The research project also identified strategies, which can be employed by manufacturing plants to implement the enablers in achieving volume flexibility

Decision-based genetic algorithms for solving multi-period project scheduling with dynamically experienced workforce

The importance of the flexibility of resources increased rapidly with the turbulent changes in the industrial context, to meet the customers’ requirements. Among all resources, the most important and considered as the hardest to manage are human resources, in reasons of availability and/or conventions. In this article, we present an approach to solve project scheduling with multi-period human resources allocation taking into account two flexibility levers. The first is the annual hours and working time regulation, and the second is the actors’ multi-skills. The productivity of each operator was considered as dynamic, developing or degrading depending on the prior allocation decisions. The solving approach mainly uses decision-based genetic algorithms, in which, chromosomes don’t represent directly the problem solution; they simply present three decisions: tasks’ priorities for execution, actors’ priorities for carrying out these tasks, and finally the priority of working time strategy that can be considered during the specified working period. Also the principle of critical skill was taken into account. Based on these decisions and during a serial scheduling generating scheme, one can in a sequential manner introduce the project scheduling and the corresponding workforce allocations