2024. március 29., péntek

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Abstract

Regarding to the total investment cost, the efficient arrangement of the construction-site is essential. Within the construction-site there are huge material flows between the connected objects – e.g. raw material- and additional storage areas, machines, and the being built structure –, increasing the operational expenses via their material handling need. Therefore the final implementing cost of the building is risen, while there is no value addition. This article shows the potential of making an optimal approximated construction-site arrangement using the principals of factory layout planning. Our aim is to give a recommendation for creating a semi-optimal arrangement, all based on the already efficiently used (approached from the principals of logistics) methods and tools of factory layout planning, corresponding them with the speciality of constructions.

The issue of factory layout planning in logistics

The factory layout planning is part of production logistics (as an intra-logistics topic), which researches the possibility of efficient topology of the manufacturing involved production facilities, materials and human resources. By the phrase "factory layout planning" we refer to the relative positioning of the manufactory buildings, facilities, workplaces, production lines and machines [1].

By creating the factory layout planning we are simultaneously determining the length of material handling routes, the space requirements of workshops and warehouses, the human resource requirement of machine-handling and waiting times between processes, which all affect the lead time of the product [1]. Therefore, it can be said that an inefficient layout (according to the previously mentioned aspects) has an increasing effect on the first cost of the product. Thus, a bad layout plan is – even though indirectly – obviously increasing the manufactured product's final price.

From the logistical point of view, an emplacement is ideal, when the material flow is permanent and is happening via the shortest route through the manufacturing structure.

Consequently, the following things have an influence on the layout:

  • the boundaries created by the technology,
  • the sequence of the operations,
  • the space requirements of objects (workplaces, machines, material storage areas),
  • the type of the implemented material handling system (fractional or continuous),
  • connection points of communal services,
  • the givens of the extant (or the new) building,
  • the various magisterial specifications and standards [1].

All these manipulating factors reduce the scope of possible solutions of the ideal layout plan, while making the objective function used for optimizing more complex. Hence throughout the resolving of the problem we have to neglect some of the factors, or make the commonly used methods capable of handling complicated objective functions, by making them to be able to manage advanced restrictive systems with intelligent solutions.

One way to reduce the field of potential solutions is to determine the main category of the layout. The various objects within different manufacturing systems can be putted in clusters based on the multiplicity of their connections to other objects (cooperation rate). Based on that, the emplacement of the machines can be unique, linear, grouped or workshop-like [1]. It is expedient to solve the arrangement of these main categories considering their specialities, using a different solving methods.

Based on the mathematical operability, the classic resolving technique of layout planning can be split into two different types, and by this realization, the calculations can be eased. Throughout the planning of linear factory layouts, we have to implement new objects (e.g. machines) into an already existing manufacturing system in a way that the improvement of material handling performance – generated between already existing and implemented objects – is minimal. It has to be told, that in this method, we are ignoring the material flows between the extant, and also between the installed machines. In this case, the progressive method gives us a classic, approximating result, enumeration and the Hungarian method gives an optimal outcome [1].

By the quadratic factory layout planning the aim is to install a totally new, isolated machinery (isolated by the manner of optimizing). The task during a creation of an ideal system is to develop a whole new arrangement, where the material handling performance is minimal. Most of the classic resolving methods – such as the heuristic approaching CRAFT and PACK, the step-by-step built triangle method, the column procedure, or the fictive sequence of operations approach – comes up with a rough result. The optimal emplacement can be calculated using enumeration or Branch and Bound techniques [1, 2, 7].

The comprehension of construction-site planning through factory layout planning

Talking about construction industry we can define (directly or indirectly involved) objects and – mainly logistic like – processes, which can be realized on the site. Between the forming of a construction-site and factory layout planning a tight parallel can be drawn, as we can match

  • construction industry machines and raw- or semi-finished product storage areas with objects that can be found in a factory,
  • the building materials and the construction involved addition-materials with the products that go through the manufacturing processes,
  • the material handling processes at the construction with connections between the objects in the factory.

Therefore, the following points have an influence on planning the topology:

  • the sequence of the construction sub-processes,
  • the area requirement of the emplaced implements, construction machines, storages and manipulation areas,
  • the applied fractionally (e.g. front loaders, small lifting handheld means of transports) or continuously working (e.g. bucket elevator, belt-conveyor) material handling systems,
  • various magisterial specifications, standards, and
  • the available transportation and communal connection possibilities.

Fig-1-web

Based on the above mentioned, it can be stated that the arranging a construction-site can be matched with factory layout planning (illustrated on the Figure 1), but we have to consider the special differences caused by the characteristics of the construction in general [3]. While in a factory the installed facilities usually work at their determined position for months or even years, at a construction it can be totally different, since their position can be changed through the various phases.

The efficient arrangement is strongly depend on the actual construction stage (which can be changed on a week-by-week basis), thus the involved objects' positions are not permanent, for instance

  • in some cases, during the different phases, there are different material, additional product, machine, and temporary built structure demands, which take place in different places within the construction field,
  • the tower-crane's (which is involved during many weight-lifting processes) input and output positions are changeful,
  • in the case of linear constructions (e.g. speedways, railways) the expropriated area is constantly changing.

Between the intersections – which can be material handling machines, manufacturing locations and interventional points – the connections are unidirectional in most cases. Based on the mentioned considerations, we can state that the main category of a casual construction layout (even if it is a linear-, high- or deep construction) can be classified as linear, grouped or workshop-like arrangement (based on the cooperation rate) with a constantly changing machinery [4, 6].

Illustration of the similarity of construction-site arrangement and layout planning

The following situation is given: we are at the first phase of an open field investment, where only the built structure's position is determined, the objects on the site have not been placed yet. Our aim is to make an arrangement of the current phase involved objects (e.g. various machines, raw- and additional material storages, delivery points), within the summary of the induced material handling performance is minimal. This emplacement is made for all the phases of the construction (in a phase, the involved objects, the demand of those objects and the connections between them remain the same). It can be easily realized that it is a quadratic layout planning problem.

During the construction, throughout the progression of the process, we allocate objects on the site. By finishing a phase, there are objects that are unnecessary for the next step, as well as new ones (that we need to implement to be able to accomplish the next stage). The issue of planning the new site arrangement (which we eager to make optimal) can be approached from two different directions:

  • The following case leads to a linear layout planning problem: after finishing a phase, we have to emplace new objects on the area emptied by the unneeded objects (from the previous stage), while the place of the existing objects remains the same. Our goal is to minimalize the material handling performance generated by the implementation of the new items (which means, that we focus on the relations between the existing and newly allocated objects).
  • References

    [1] Prezenszki (szerk.): Logisztika I. pp. 508-515., Budapest, 2004.
    [2] L. Wayne Winston: Operációkutatás I-II. (Módszerek és alkalmazások), Aula kiadó, 2003
    [3] Gábor Bohács, András Gyimesi (2014): Developing a New Model and Pilot System for Construction – Periodica Polytechnica – Budapest, Hungary
    [4] Tommelein, I. D., Levitt, R. E., and Hayes-Roth, B.: „SightPlan Model for Site Layout.", Journal of Construction Engineering and Management, ASCE, 1992.
    [5] K. E.-R. A. Khalafallah, Safety and cost considerations in site layout planning.
    [6] Hamiani, A. (1989). „Knowledge Representation for the Site Layout Problem." Sixth Conference on Computing in Civil Engineering, New York.
    [7] Prezenszki (szerk.): Logisztika II., Budapest, 2000.
  • We get a quadratic layout planning problem when we handle all the objects, associated with the new phase – ignoring whether it is a new or an extant one – all together. The aim is to make a layout that results in the lowest material handling performance within the newly arranged system (summarizing every connection between each object).

So what determines our approach of an actual issue? Classifying a site-planning problem depends on the specific costs of material handling, plantation and relocation of objects [5]. Talking about linear site planning, the relocation cost of the existing machinery is can not be defined, reducing the range of possible layouts, therefore excluding the total optimum of a problem (the best we can find is a local extreme). In the case of creating a quadratic arrangement, the range of possibilities are way wider, consequently a lower sum material handling performance becomes a possibility, however the relocation costs of the existing machines must be taken under consideration. Therefore, the problem should be solved by dealing with both of the described expenses (which depend from one another).

Summary

Fig-2-webThe challenge of creating an ideal factory layout plan and construction-site planning reveals correspondence from the aspect of logistical planning. The arrangement involved objects, processes, aims and conditions can be matched with elements associated with construction, thus the already existing optimizing algorithms – talking about factory layout planning – can be used for both scenarios (as we can see on Figure 2).This means, that the working area can be used efficiently, the logistical processes can be fulfilled with less waste and the space demand of the whole procedure might reduce. The parallelizing can be done from both aspects, accordingly the methods used in the field of construction can be adapted for factory layout planning with a fair chance, resulting in the cut of time requirement of a research.

 

Support

The development that has been introduced in this paper is a part of a Hungarian Government financed research project (reference nr. KTIA_AIK_12-1-2013-0009). The whole budget (c.a. 1,36 Million EUR) of the research is from the KTIA fund.

 

Norbert Fésüs
Logistical and process developing engineer, whose research and educational area strongly connects to the modeling of logistic problems, as well as the development and optimizing of procedures. PhD student at BME Faculty of Transportation Engineering and Vehicle Engineering, Department of Material Handling and Logistics Systems. Title of his PhD research article: Non-conventional optimizing methods to improve the logistical efficiency of service-like processes. E-mail: Ez az e-mail cím a spamrobotok elleni védelem alatt áll. Megtekintéséhez engedélyeznie kell a JavaScript használatát. .

Norbert Antal
Departmental engineer at BME Faculty of Transportation Engineering and Vehicle Engineering, Department of Material Handling and Logistics Systems. The leader of BME Lean LOGISTIC system and process developing group. Main professional fields: logistical controlling, improving of intra-logistics processes. E-mail: Ez az e-mail cím a spamrobotok elleni védelem alatt áll. Megtekintéséhez engedélyeznie kell a JavaScript használatát. .

Dénes Boros
Departmental demonstrator at BME Faculty of Transportation Engineering and Vehicle Engineering, Department of Material Handling and Logistics Systems. Research areas: artificial intelligence based industrial image processing, artificial neural networks, automated systems at logistics. E-mail: Ez az e-mail cím a spamrobotok elleni védelem alatt áll. Megtekintéséhez engedélyeznie kell a JavaScript használatát. .

 

 

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