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Prof. Piotr Jaskowski
Lublin University of technology Faculty of Civil Engineering and Architecture

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0 Construction Management
0 Project Management
0 Scheduling
0 operational research
0 optimisation methods

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Short Biography

PIOTR JAŚKOWSKI is associate professor at Lublin University of Technology, Poland. He is a Head of the Department of Construction Methods and Management He is a member of the Section of the Engineering of Construction Projects in Civil Engineering Committee of Polish Academy of Science. He is the member of EURO Working Group “OR in Sustainable Development and Civil Engineering”. His research interests include the organization and modelling of construction processes, construction projects scheduling, optimization techniques.

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Journal article
Published: 14 January 2021 in Symmetry
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The problem of setting prices for construction works is significant for both the investor and contractor companies. The periodically occurring instabilities in the economy require investment process participants to perform detailed market analyses and assessments, as well as to monitor price forecasts in construction. It is only after such an assessment that it is possible within the framework of the initial assumptions for cost calculation to select the basis for setting prices and their levels. The identification and analysis of the risks related to uncontrolled price increases allow contractors to secure their businesses by developing bids that ensure maximum profit. In view of the above, this study proposes an approach based on the use of game theory against nature to identify the optimal variant of a bid estimate. The study considers price forecasts for construction products, which may reduce the negative impact in case the prices increase. The obtained results confirmed the effectiveness of the used decision-making support methods, indicating the optimal strategy to reduce financial losses in times of market instability. The proposed approach also allows for a balance (symmetry) between maximum profit and probability of winning the contract.

ACS Style

Łukasz Rzepecki; Piotr Jaśkowski. Application of Game Theory against Nature in Supporting Bid Pricing in Construction. Symmetry 2021, 13, 132 .

AMA Style

Łukasz Rzepecki, Piotr Jaśkowski. Application of Game Theory against Nature in Supporting Bid Pricing in Construction. Symmetry. 2021; 13 (1):132.

Chicago/Turabian Style

Łukasz Rzepecki; Piotr Jaśkowski. 2021. "Application of Game Theory against Nature in Supporting Bid Pricing in Construction." Symmetry 13, no. 1: 132.

Journal article
Published: 08 January 2021 in Sustainability
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In the literature on the scheduling of construction projects it is difficult to find a justification for adopting the criteria for evaluating work schedules based explicitly on the preferences of those who develop them. This article tries to fill this gap and provide information on the preferences of construction site managers for sustainable scheduling and organization of construction projects. The publication focuses on the views and needs of construction site engineering staff regarding methods of work organization, the need to reduce downtimes in the work of crews, the deadline for project realization and the selection of crews for tasks. This information was obtained on the basis of surveys conducted among managerial staff of various levels (74 people). The authors hope that the information provided in this publication will allow the creation of more reliable tools to support construction managers better adapted to their preferences and needs, and therefore more likely to be applied in practice.

ACS Style

Michał Tomczak; Piotr Jaśkowski. Preferences of Construction Managers Regarding the Quality and Optimization Criteria of Project Schedules. Sustainability 2021, 13, 544 .

AMA Style

Michał Tomczak, Piotr Jaśkowski. Preferences of Construction Managers Regarding the Quality and Optimization Criteria of Project Schedules. Sustainability. 2021; 13 (2):544.

Chicago/Turabian Style

Michał Tomczak; Piotr Jaśkowski. 2021. "Preferences of Construction Managers Regarding the Quality and Optimization Criteria of Project Schedules." Sustainability 13, no. 2: 544.

Journal article
Published: 14 December 2020 in IEEE Access
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A variety of schedule compression techniques are used to get delayed construction projects “back on tracks”. This paper presents a new optimization approach to schedule crashing by relocating some of the workers from non-critical to critical processes (changing composition of crews using the initial pool of workers) and employing additional resources. The authors describe their idea in the form of a mixed-integer linear problem. A numerical example illustrates the merits of the proposed approach. The method may become a practical support in construction scheduling decisions.

ACS Style

Michal Tomczak; Piotr Jaskowski. Crashing Construction Project Schedules by Relocating Resources. IEEE Access 2020, 8, 224522 -224531.

AMA Style

Michal Tomczak, Piotr Jaskowski. Crashing Construction Project Schedules by Relocating Resources. IEEE Access. 2020; 8 (99):224522-224531.

Chicago/Turabian Style

Michal Tomczak; Piotr Jaskowski. 2020. "Crashing Construction Project Schedules by Relocating Resources." IEEE Access 8, no. 99: 224522-224531.

Journal article
Published: 12 November 2020 in Applied Sciences
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Both the construction clients and the contractors want their projects delivered on time. Construction schedules, usually tight from the beginning, tend to expire as the progress of works is disturbed by materializing risks. As consequence, the project’s original milestones are delayed. To protect the due date and, at the same time, avoid changes to the logic of work, the manager needs to the project progress and, if delays occur, speed up processes not yet completed. The authors investigate the problem of selecting the optimal set of actions of responding to schedule delays. They put forward a simulation-based method of selecting schedule compression measures (speeding up processes) and determining the best moment to take such actions. The idea is explained using a simple case. The results confirm that it is possible to find an easily implementable schedule crashing mode to answer schedule disturbances. The proposed method enables minimizing the cost of schedule crashing actions and the cost of delays as well as increasing the robustness of the schedule by reducing differences between the actual and the as-planned process starts. It is intended as a decision support tool to help construction managers prepare better reactive schedules. The lowest costs are achieved if the acceleration measures are implemented with some time lag to the occurrence of delays.

ACS Style

Sławomir Biruk; Piotr Jaśkowski. Selection of the Optimal Actions for Crashing Processes Duration to Increase the Robustness of Construction Schedules. Applied Sciences 2020, 10, 8028 .

AMA Style

Sławomir Biruk, Piotr Jaśkowski. Selection of the Optimal Actions for Crashing Processes Duration to Increase the Robustness of Construction Schedules. Applied Sciences. 2020; 10 (22):8028.

Chicago/Turabian Style

Sławomir Biruk; Piotr Jaśkowski. 2020. "Selection of the Optimal Actions for Crashing Processes Duration to Increase the Robustness of Construction Schedules." Applied Sciences 10, no. 22: 8028.

Journal article
Published: 08 June 2020 in JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT
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The highest degree of construction works harmonization can be achieved when planning a repetitive project with processes replicated many times in work zones of identical size. In practice, structural considerations affect the way of dividing the object under construction into zones differing in terms of scope and quantity of works. Due to this fact, individual processes are being allotted to different non-identical zones. Most methods intended for scheduling repetitive processes were developed with the assumption that the work zones are identical and that a particular process cannot be concurrently conducted. To address this gap, the authors put forward a mathematical model of the problem of scheduling of repetitive processes that are repeated in different work zones with the following assumption: several crews of the same type are available, thus particular process can run simultaneously in different locations. The aim of optimization is minimizing the idle time of all crews under the constraint of not exceeding the contractual project duration. The proposed mixed binary linear programming model can be solved using software available in the market or developed into a dedicated system to support decisions. To illustrate the benefits of the model, an example of scheduling interior finishing works was provided.

ACS Style

Piotr Jaskowski; Slawomir Biruk. SCHEDULING OF REPETITIVE CONSTRUCTION PROCESSES WITH CONCURRENT WORK OF SIMILARLY SPECIALIZED CREWS. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2020, 26, 579 -589.

AMA Style

Piotr Jaskowski, Slawomir Biruk. SCHEDULING OF REPETITIVE CONSTRUCTION PROCESSES WITH CONCURRENT WORK OF SIMILARLY SPECIALIZED CREWS. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT. 2020; 26 (6):579-589.

Chicago/Turabian Style

Piotr Jaskowski; Slawomir Biruk. 2020. "SCHEDULING OF REPETITIVE CONSTRUCTION PROCESSES WITH CONCURRENT WORK OF SIMILARLY SPECIALIZED CREWS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 26, no. 6: 579-589.

Journal article
Published: 01 May 2020 in Journal of Construction Engineering and Management
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A significant number of construction projects involve repetitive processes. Planning them occurs to be a complex task. Network methods traditionally applied to construction scheduling prove inefficient in the case of repetitive construction projects (RCPs) due to the increased number of relationships among processes, locations (units), and resources. Frequently, the aim of scheduling RCPs is making the full use of the resources’ capacity, thereby ensuring continuity of the crews’ work. To achieve this, the planner typically allows discontinuity of some secondary processes to shift resources to the key processes, allowing optional modes of process delivery and introducing soft precedence relations between processes. This paper presents a new way of increasing the continuity of work of a general contractor’s crews in RCPs by employing subcontractors’ crews. A deterministic mathematical model of the mixed-integer linear problem of a repetitive (nonlinear) project was formulated to find a schedule that minimizes the downtime of the general contractor’s crews under constraints of a maximum acceptable total project duration and a maximum acceptable cost of the works commissioned to subcontractors; the model accounts for the limited availability of crews. Application of the model is illustrated by an example.

ACS Style

Michał Tomczak; Piotr Jaśkowski. New Approach to Improve General Contractor Crew’s Work Continuity in Repetitive Construction Projects. Journal of Construction Engineering and Management 2020, 146, 04020043 .

AMA Style

Michał Tomczak, Piotr Jaśkowski. New Approach to Improve General Contractor Crew’s Work Continuity in Repetitive Construction Projects. Journal of Construction Engineering and Management. 2020; 146 (5):04020043.

Chicago/Turabian Style

Michał Tomczak; Piotr Jaśkowski. 2020. "New Approach to Improve General Contractor Crew’s Work Continuity in Repetitive Construction Projects." Journal of Construction Engineering and Management 146, no. 5: 04020043.

Journal article
Published: 01 December 2019 in Archives of Civil Engineering
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Most construction projects involve subcontracting some work packages. A subcontractor is employed on the basis of their bid as well as according to their availability. A viable schedule must account for resource availability constraints. These resources (e.g. crews, subcontractors) engage in many projects, so they become at the disposal for a new project only in certain periods. One of the key tasks of a planner is thus synchronizing the work of resources between concurrent projects. The paper presents a mathematical model of the problem of selecting subcontractors or general contractor’s crews for a time-constrained project that accounts for the availability of contractors, as well as for the cost of subcontracting works. The proposed mixed integer-binary linear programming model enables the user to perform the time/cost trade-off analysis.

ACS Style

S. Biruk; P. Jaskowski; M. Krzemiński. Model of Construction Subcontractors Selection with Time Windows for their Availability. Archives of Civil Engineering 2019, 65, 295 -307.

AMA Style

S. Biruk, P. Jaskowski, M. Krzemiński. Model of Construction Subcontractors Selection with Time Windows for their Availability. Archives of Civil Engineering. 2019; 65 (4):295-307.

Chicago/Turabian Style

S. Biruk; P. Jaskowski; M. Krzemiński. 2019. "Model of Construction Subcontractors Selection with Time Windows for their Availability." Archives of Civil Engineering 65, no. 4: 295-307.

Conference paper
Published: 18 September 2019 in IOP Conference Series: Materials Science and Engineering
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The selection of suppliers is one of the key issues of supply logistics of any business entity. Due to the globalization of the economy and the rapid technological progress, the choice of products and the number of vendors is growing, which makes the selection process difficult. The specific character of the construction projects (one-off contracts with no incentives of the steady orders from one client, the need to adjust the batch size to the pace of the construction works whereas this pace is affected by risks and uncertainties, short time for planning, etc.) poses extra challenges to the suppliers' production and transportation capacities and defines what "capable suppliers" mean for the project success. Therefore, the criteria of a construction project supplier selection go far beyond the obvious "price". They need to refer to the supplier's bid as well as the supplier's own qualities (financial standing, reputation, flexibility). Though the selection process is expected to be based on unequivocal and objective input, in practice, it rests upon opinions and artificial measures used in lieu of the complete information. This input is, thus, fuzzy by nature and ignoring this fact may lead to wrong decisions. Therefore, the authors analyze the ways of quantifying supplier selection criteria and the methods of using them in the decision-making process presented in the literature. Then, they present a numerical example of supplier selection based on AHP with the fuzzy input, juxtaposing it with the results of the "classical" AHP with a crisp input. The results are different. Though this difference cannot be generalized, it indicates that the method of analysis may strongly affect the decision-makers choices.

ACS Style

Sławomir Biruk; Piotr Jaskowski; Agata Czarnigowska. Fuzzy AHP for selecting suppliers of construction materials. IOP Conference Series: Materials Science and Engineering 2019, 603, 032093 .

AMA Style

Sławomir Biruk, Piotr Jaskowski, Agata Czarnigowska. Fuzzy AHP for selecting suppliers of construction materials. IOP Conference Series: Materials Science and Engineering. 2019; 603 (3):032093.

Chicago/Turabian Style

Sławomir Biruk; Piotr Jaskowski; Agata Czarnigowska. 2019. "Fuzzy AHP for selecting suppliers of construction materials." IOP Conference Series: Materials Science and Engineering 603, no. 3: 032093.

Conference paper
Published: 18 September 2019 in IOP Conference Series: Materials Science and Engineering
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The Monte Carlo simulation has become a standard tool in the practice of planning risk-affected projects. In particular, it is frequently applied to testing the impact of risk on schedule networks with deterministic structures and random activity durations defined by distribution functions of any type. The accuracy of simulation-based estimates can be improved by increasing the number of replications or by applying variance reduction methods. This paper focuses on the latter and analyzes the impact of the variance reduction method on the scale of the standard error of the estimated mean value of project duration. Three methods of variance reduction were examined: the Quasi-Monte Carlo with Weyl sequence sampling, the antithetic variates, and the Latin Hypercube Sampling. The object of the simulation experiment was a sample network model with the activity durations of triangular distributions. This type of distribution was selected as it is often applied in the practice of construction scheduling to capture the variability of operating conditions in the absence of grounds for assuming other types of distribution. The results of the sample simulation provided an indirect proof that applying variance reduction measures may reduce the time of the simulation experiment (reduced number of replications) as well as improve the confidence in the estimates of the model's characteristics.

ACS Style

Slawomir Biruk; Piotr Jaskowski; Agata Czarnigowska. Assessing the Efficiency of Variance Reduction Methods in the Construction Project Network Simulation. IOP Conference Series: Materials Science and Engineering 2019, 603, 032094 .

AMA Style

Slawomir Biruk, Piotr Jaskowski, Agata Czarnigowska. Assessing the Efficiency of Variance Reduction Methods in the Construction Project Network Simulation. IOP Conference Series: Materials Science and Engineering. 2019; 603 (3):032094.

Chicago/Turabian Style

Slawomir Biruk; Piotr Jaskowski; Agata Czarnigowska. 2019. "Assessing the Efficiency of Variance Reduction Methods in the Construction Project Network Simulation." IOP Conference Series: Materials Science and Engineering 603, no. 3: 032094.

Journal article
Published: 27 June 2019 in Open Engineering
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The approach used by construction companies to determine bid prices is an element of their strategy used to win jobs in competitive tenders. Such strategies build upon an analysis of the contactor’s potential and capabilities (am I able to deliver? am I eligible to participate in the tender?), and the analysis of the economic environment, including the expected behavior of competitors. The tender strategy sets out both the guidelines and the procedure in deciding whether or not to bid as well as the rules for determining the price. The price, on the one hand, should be high enough to cover expected direct and indirect costs as well as risk-adjusted profit. On the other hand, it needs to be low enough to be considered most attractive (typically: the lowest) among the prices offered by the competitors. The paper focuses on the price definition component of the bidding strategy. It provides a brief overview of the existing methods that support bidding decisions by comparing their demand for input and limitations in practical applications and presents a simulation-based method supporting the determination of the profit ratio. This probabilistic method assumes the existence of a positive correlation between the prices offered by the competitors. Its application is illustrated by means of a numerical example. The outcomes of the simulation prompt the amount of the profit margin that maximizes the expected value of the contractor’s profit.

ACS Style

Piotr Jaśkowski; Agata Czarnigowska. Contractor’s bid pricing strategy: a model with correlation among competitors’ prices. Open Engineering 2019, 9, 159 -166.

AMA Style

Piotr Jaśkowski, Agata Czarnigowska. Contractor’s bid pricing strategy: a model with correlation among competitors’ prices. Open Engineering. 2019; 9 (1):159-166.

Chicago/Turabian Style

Piotr Jaśkowski; Agata Czarnigowska. 2019. "Contractor’s bid pricing strategy: a model with correlation among competitors’ prices." Open Engineering 9, no. 1: 159-166.

Journal article
Published: 06 March 2019 in Computation
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This study adopts the flow shop concept used in industrial production to schedule repetitive non-linear construction projects, where specialized groups of workers execute processes in work zones (buildings) in a predefined order common to all groups. This problem is characteristic of construction projects that involve erecting multiple buildings. As the duration of the project heavily depends upon the sequence of the work zones, this study aims at providing a model and a practical approach for finding the optimal solution that assures the shortest duration of the project, allows the contractor to complete particular work zones (buildings) as soon as possible (without idle time), and conforms to a predefined sequence of work zone completion. This last constraint may arise from the client’s requirements or physical conditions of the project and has not been addressed by existing scheduling methods. Reducing the duration of the entire project brings the benefit of lower indirect costs and, if accompanied by a reduced duration of completing particular buildings (i.e., work zones), may also provide the opportunity to sell project deliverables sooner, thus improving the economic efficiency of the project. In search of optimal schedules, the authors apply the algorithms of Minimum Hamiltonian Cycle/Asymmetric Traveling Salesman Problem (ATSP).

ACS Style

Piotr Jaśkowski; Sławomir Biruk. Minimizing the Duration of Repetitive Construction Processes with Work Continuity Constraints. Computation 2019, 7, 14 .

AMA Style

Piotr Jaśkowski, Sławomir Biruk. Minimizing the Duration of Repetitive Construction Processes with Work Continuity Constraints. Computation. 2019; 7 (1):14.

Chicago/Turabian Style

Piotr Jaśkowski; Sławomir Biruk. 2019. "Minimizing the Duration of Repetitive Construction Processes with Work Continuity Constraints." Computation 7, no. 1: 14.

Conference paper
Published: 23 February 2019 in IOP Conference Series: Materials Science and Engineering
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A competitive tender with the lowest price as the only (or the main) criterion of contractor selection is one of the most common approaches to procurement in construction. On the one hand, it is expected to offer the greatest benefits of competition to the client; on the other hand, it forces numerous competitors to engage time and resources for bid preparation with a low chance to win the job. To stay in the market, the contractor needs to foresee the behaviour of the competitors (which implies knowing who they are and what prices are they likely to offer), and apply some strategy to increase his/her probability to win without compromising the profits. A number of mathematical models of competitive bidding process can be found in the literature, from the earliest basing on probability theory, to more recent that apply artificial neural networks or fuzzy set theory. The paper presents a probability-based method of estimating the optimal bid price (which means a price of maximum expected value of the contractor's profit) in lowest bid tenders that stems from Friedman's model (1956). The authors discuss the assumptions that make the model applicable to real-life situations of specialized construction contractors. A worked example based on case-study data is presented to illustrate the idea. To be used in practice, the proposed model has to be fed with up-to-date results of tenders (number of competitors, and their bid prices). The proposed strategy thus rests upon careful monitoring of the market and internal condition of the bidder.

ACS Style

Piotr Jaskowski; Sławomir Biruk; Agata Czarnigowska. Strategy for Mark-up Definition in Competitive Tenders for Construction Work. IOP Conference Series: Materials Science and Engineering 2019, 471, 112060 .

AMA Style

Piotr Jaskowski, Sławomir Biruk, Agata Czarnigowska. Strategy for Mark-up Definition in Competitive Tenders for Construction Work. IOP Conference Series: Materials Science and Engineering. 2019; 471 (11):112060.

Chicago/Turabian Style

Piotr Jaskowski; Sławomir Biruk; Agata Czarnigowska. 2019. "Strategy for Mark-up Definition in Competitive Tenders for Construction Work." IOP Conference Series: Materials Science and Engineering 471, no. 11: 112060.

Conference paper
Published: 23 February 2019 in IOP Conference Series: Materials Science and Engineering
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The continuous growth of competition on the construction market results in the fact that construction companies are forced to keep searching for solutions facilitating the building process and construction logistics. In the recent decades, one of the most fascinating ideas which enable a real improvement in the aspect of a company's competitiveness on the market is supply chain management. It has undergone a transformation from fragmented actions to integrated operations intending to optimize the flow of physical resources and information. The first step towards the application of the modern logistics tools is the selection and evaluation of entities involved in a cooperation within the supply chain framework. The selection of reliable partners to supply a construction site or a building company may reduce the operational costs, minimize inventory and improve timeliness as well as the quality of offered services. Any mistakes made in the process of supplier selection may lead to issues such as supply delays, difficulties in keeping contract deadlines and even complete failure of a project or bankruptcy of a construction company. An 18th century criterion for the selection of the most preferable candidate developed by Nicolas de Condorcet is commonly accepted owing to its fair rules of choice (anyone who defeats most of their competitors in a direct confrontation wins). Due to its democratic approach, most criteria decide as to the selection of the winner. Should the choice of a winner or establishing a Condorcet ranking from the perspective of the social choice theory prove impossible, the selected candidate ought to be as much similar to a winner in the Condorcet sense as possible. The theory was developed in order to facilitate the selection of the most suitable candidate in the election, however it may also find application in the selection of a supply chain elements evaluated with the use of multiple criteria. There are a number of decision-making methods which fulfil the Condorcet criterion. They vary in their computational complexity and may provide different final order. The intention of this paper is to review the methods which may offer support while selecting the most preferable supplier of construction products.

ACS Style

Michal Tomczak; Sławomir Biruk; Piotr Jaskowski. Selection of Construction Products Suppliers According to the Condorcet Criterion. IOP Conference Series: Materials Science and Engineering 2019, 471, 112068 .

AMA Style

Michal Tomczak, Sławomir Biruk, Piotr Jaskowski. Selection of Construction Products Suppliers According to the Condorcet Criterion. IOP Conference Series: Materials Science and Engineering. 2019; 471 (11):112068.

Chicago/Turabian Style

Michal Tomczak; Sławomir Biruk; Piotr Jaskowski. 2019. "Selection of Construction Products Suppliers According to the Condorcet Criterion." IOP Conference Series: Materials Science and Engineering 471, no. 11: 112068.

Journal article
Published: 10 September 2018 in Przegląd Naukowy Inżynieria i Kształtowanie Środowiska
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Authors put forward a mixed linear programming model for optimizing supplies of construction material consumed in non-uniform way. The model enables the user to consider cost implications of material substitution and selecting suppliers that offer the material at varying level of pre-processing, as well as buying to stock with limited capacity of stacking areas. The model serves finding the economic order quantities in consecutive units of time and selecting supply chains.

ACS Style

Agata Czarnigowska; Piotr Jaśkowski; Anna Sobotka. Model decyzyjny wyboru łańcuchów zaopatrzenia przedsięwzięcia w wyroby budowlane. Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 2018, 27, 269 -279.

AMA Style

Agata Czarnigowska, Piotr Jaśkowski, Anna Sobotka. Model decyzyjny wyboru łańcuchów zaopatrzenia przedsięwzięcia w wyroby budowlane. Przegląd Naukowy Inżynieria i Kształtowanie Środowiska. 2018; 27 (3):269-279.

Chicago/Turabian Style

Agata Czarnigowska; Piotr Jaśkowski; Anna Sobotka. 2018. "Model decyzyjny wyboru łańcuchów zaopatrzenia przedsięwzięcia w wyroby budowlane." Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 27, no. 3: 269-279.

Journal article
Published: 29 June 2018 in JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT
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Renewable resource levelling is the core of the scheduling process. A perfect schedule ensures that resource supply corresponds to the demand at every unit of project time. A classic approach to resource levelling in schedules with predefined project completion dates consists in manipulating processes start dates. Resource deployment can be also improved by considering alternative construction processes execution modes with various crew formations, and by allowing activities to be split. There are other possibilities: in many practical cases, the activities’ precedence logic predefined in the network model can be changed with no harm to the project outcome. Within the structure of the project network model, some precedence relations between activities would definitely be of fixed (hard) character, whereas some might allow the activities to be executed at the same time or arranged in a variety of logical sequences. The authors use soft precedence relations that let the processes run in reversed order or that can be cancelled, in search for improved resource usage profiles. The benefits of scheduling with soft precedence relations are demonstrated by an example.

ACS Style

Piotr Jaskowski; Slawomir Biruk. REDUCING RENEWABLE RESOURCE DEMAND FLUCTUATION USING SOFT PRECEDENCE RELATIONS IN PROJECT SCHEDULING. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2018, 24, 355 -363.

AMA Style

Piotr Jaskowski, Slawomir Biruk. REDUCING RENEWABLE RESOURCE DEMAND FLUCTUATION USING SOFT PRECEDENCE RELATIONS IN PROJECT SCHEDULING. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT. 2018; 24 (4):355-363.

Chicago/Turabian Style

Piotr Jaskowski; Slawomir Biruk. 2018. "REDUCING RENEWABLE RESOURCE DEMAND FLUCTUATION USING SOFT PRECEDENCE RELATIONS IN PROJECT SCHEDULING." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 24, no. 4: 355-363.

Journal article
Published: 01 June 2018 in Automation in Construction
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ACS Style

Piotr Jaśkowski; Anna Sobotka; Agata Czarnigowska. Decision model for planning material supply channels in construction. Automation in Construction 2018, 90, 235 -242.

AMA Style

Piotr Jaśkowski, Anna Sobotka, Agata Czarnigowska. Decision model for planning material supply channels in construction. Automation in Construction. 2018; 90 ():235-242.

Chicago/Turabian Style

Piotr Jaśkowski; Anna Sobotka; Agata Czarnigowska. 2018. "Decision model for planning material supply channels in construction." Automation in Construction 90, no. : 235-242.

Construction management
Published: 08 January 2018 in KSCE Journal of Civil Engineering
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The selection of a general contractor for construction works is one of the most important decisions made throughout the entire construction project. It may be decisive in the success or failure of the project (e.g. delays in the commissioning of works, exceeding the budget, low quality of works). The article presents a method for supporting group decision-making in the contractor qualification process. The proposed method is a development of Mikhailov's approach to Fuzzy Analytic Hierarchy Process. It consists in the aggregation of the decision makers' judgments using type-2 fuzzy sets, allowing for inaccuracy of the decision-maker’s assessment. The use of an unbiased estimator of standard deviation for determining compromise evaluation enables the small size of the expert group and deviations in their evaluations to be taken into consideration. The quality of the solution obtained through this method was compared with the results obtained by means of Mikhailov’s Fuzzy Preference Programming and Enea & Piazza Method. The use of the proposed method generated better results for this example of preparing a ranking of contractors than the two other methods discussed. The method presented herein may also be proposed for solving decision-making problems in other spheres.

ACS Style

Michał Tomczak; Piotr Jaśkowski. Application of Type-2 Interval Fuzzy Sets to Contractor Qualification Process. KSCE Journal of Civil Engineering 2018, 22, 2702 -2713.

AMA Style

Michał Tomczak, Piotr Jaśkowski. Application of Type-2 Interval Fuzzy Sets to Contractor Qualification Process. KSCE Journal of Civil Engineering. 2018; 22 (8):2702-2713.

Chicago/Turabian Style

Michał Tomczak; Piotr Jaśkowski. 2018. "Application of Type-2 Interval Fuzzy Sets to Contractor Qualification Process." KSCE Journal of Civil Engineering 22, no. 8: 2702-2713.

Conference paper
Published: 01 October 2017 in IOP Conference Series: Materials Science and Engineering
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Many civil engineering projects involve sets of tasks repeated in a predefined sequence in a number of work areas along a particular route. A useful graphical representation of schedules of such projects is time-distance diagrams that clearly show what process is conducted at a particular point of time and in particular location. With repetitive tasks, the quality of project performance is conditioned by the ability of the planner to optimize workflow by synchronizing the works and resources, which usually means that resources are planned to be continuously utilized. However, construction processes are prone to risks, and a fully synchronized schedule may expire if a disturbance (bad weather, machine failure etc.) affects even one task. In such cases, works need to be rescheduled, and another optimal schedule should be built for the changed circumstances. This typically means that, to meet the fixed completion date, durations of operations have to be reduced. A number of measures are possible to achieve such reduction: working overtime, employing more resources or relocating resources from less to more critical tasks, but they all come at a considerable cost and affect the whole project. The paper investigates the problem of selecting the measures that reduce durations of tasks of a linear project so that the cost of these measures is kept to the minimum and proposes an algorithm that could be applied to find optimal solutions as the need to reschedule arises. Considering that civil engineering projects, such as road building, usually involve less process types than construction projects, the complexity of scheduling problems is lower, and precise optimization algorithms can be applied. Therefore, the authors put forward a linear programming model of the problem and illustrate its principle of operation with an example.

ACS Style

Sławomir Biruk; Piotr Jaśkowski; Agata Czarnigowska. Updating Linear Schedules with Lowest Cost: a Linear Programming Model. IOP Conference Series: Materials Science and Engineering 2017, 245, 72011 .

AMA Style

Sławomir Biruk, Piotr Jaśkowski, Agata Czarnigowska. Updating Linear Schedules with Lowest Cost: a Linear Programming Model. IOP Conference Series: Materials Science and Engineering. 2017; 245 ():72011.

Chicago/Turabian Style

Sławomir Biruk; Piotr Jaśkowski; Agata Czarnigowska. 2017. "Updating Linear Schedules with Lowest Cost: a Linear Programming Model." IOP Conference Series: Materials Science and Engineering 245, no. : 72011.

Conference paper
Published: 01 October 2017 in IOP Conference Series: Materials Science and Engineering
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Subcontracting has been a worldwide practice in the construction industry. It enables the construction enterprises to focus on their core competences and, at the same time, it makes complex project possible to be delivered. Since general contractors bear full responsibility for the works carried out by their subcontractors, it is their task and their risk to select a right subcontractor for a particular work. Although subcontractor management has been admitted to significantly affect the construction project's performance, current practices and past research deal with subcontractor management and scheduling separately. The proposed model aims to support subcontracting decisions by integrating subcontractor selection with scheduling to enable the general contractor to select the optimal combination of subcontractors and own crews for all work packages of the project. The model allows for the interactions between the subcontractors and their impacts on the overall project performance in terms of cost and, indirectly, time and quality. The model is intended to be used at the general contractor's bid preparation stage. The authors claim that the subcontracting decisions should be taken in a two-stage process. The first stage is a prequalification – provision of a short list of capable and reliable subcontractors; this stage is not the focus of the paper. The resulting pool of available resources is divided into two subsets: subcontractors, and general contractor's in-house crews. Once it has been defined, the next stage is to assign them to the work packages that, bound by fixed precedence constraints, form the project's network diagram. Each package is possible to be delivered by the general contractor's crew or some of the potential subcontractors, at a specific time and cost. Particular crews and subcontractors can be contracted more than one package, but not at the same time. Other constraints include the predefined project completion date (the project is not allowed to take longer) and maximum total value of subcontracted work. The problem is modelled as a mixed binary linear program that minimizes project cost. It can be solved using universal solvers (e.g. LINGO, AIMMS, CPLEX, MATLAB and Optimization Toolbox, etc.). However, developing a dedicated decision-support tool would facilitate practical applications. To illustrate the idea of the model, the authors present a numerical example to find the optimal set of resources allocated to a project.

ACS Style

Sławomir Biruk; Piotr Jaśkowski; Agata Czarnigowska. Minimizing Project Cost by Integrating Subcontractor Selection Decisions with Scheduling. IOP Conference Series: Materials Science and Engineering 2017, 245, 72007 .

AMA Style

Sławomir Biruk, Piotr Jaśkowski, Agata Czarnigowska. Minimizing Project Cost by Integrating Subcontractor Selection Decisions with Scheduling. IOP Conference Series: Materials Science and Engineering. 2017; 245 (7):72007.

Chicago/Turabian Style

Sławomir Biruk; Piotr Jaśkowski; Agata Czarnigowska. 2017. "Minimizing Project Cost by Integrating Subcontractor Selection Decisions with Scheduling." IOP Conference Series: Materials Science and Engineering 245, no. 7: 72007.

Journal article
Published: 23 May 2017 in Przegląd Naukowy Inżynieria i Kształtowanie Środowiska
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During executing of construction projects enterprises seek for high level of coordinating engaged resources. This seeking evinces in providing continuity and levelling production. It enables making of entire production capability. This paper analyses scheduling work of general contractor crews, which carry out unrhytmic, noncyclic and inhomogeneous processes in deterministic conditions. The mathematical model of work gaps for general contractor crews in construction project scheduling is formulated. This model also counts crews availability limits, cost and time constraints and possibility of tasks outsourcing for subcontractors.

ACS Style

Piotr Jaśkowski; Michał Tomczak. Problem minimalizacji przestojów w pracy brygad generalnego wykonawcy w harmonogramowaniu przedsięwzięć budowlanych. Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 2017, 26, 193 -201.

AMA Style

Piotr Jaśkowski, Michał Tomczak. Problem minimalizacji przestojów w pracy brygad generalnego wykonawcy w harmonogramowaniu przedsięwzięć budowlanych. Przegląd Naukowy Inżynieria i Kształtowanie Środowiska. 2017; 26 (2):193-201.

Chicago/Turabian Style

Piotr Jaśkowski; Michał Tomczak. 2017. "Problem minimalizacji przestojów w pracy brygad generalnego wykonawcy w harmonogramowaniu przedsięwzięć budowlanych." Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 26, no. 2: 193-201.