scholarly journals Bi-Objective Scheduling Optimization for Discrete Time/Cost Trade-Off in Projects

2018 ◽  
Vol 10 (8) ◽  
pp. 2802 ◽  
Author(s):  
Hongbo Li ◽  
Zhe Xu ◽  
Wenchao Wei
Keyword(s):  
Discrete Time ◽  
Large Scale ◽  
Heuristic Algorithms ◽  
Critical Path ◽  
Large Set ◽  
Time Cost ◽  
Trade Off ◽  
Project Duration ◽  
Computational Performance ◽  
Trade Offs

In sustainable project management, time and cost are two critical factors affecting the success of a project. Time/cost trade-offs in projects accelerate the execution of some activities by increasing the amount of non-renewable resources committed to them and therefore shorten the project duration. The discrete time/cost trade-off problem (DTCTP) has been extensively studied during the past 20 years. However, due to its complexity, the DTCTP—especially the DTCTP curve problem (DTCTP-C)—has only been solved for relatively small instances. To the best of our knowledge, there is no computational performance analysis for solving the DTCTP-C on large project instances with up to 500 activities. This paper aims to fill this gap. We present two bi-objective heuristic algorithms for the DTCTP-C where both project duration and cost are minimized. The objective is to obtain a good appropriate efficient set for the large-scale instances. The first algorithm is based on the non-dominated sorting genetic algorithm II (NSGA-II) and uses a specially designed critical path-based crossover operator. The second algorithm is a steepest descent heuristic which generates efficient solutions by iteratively solving the DTCTP with different deadlines. Computational experiments are conducted to validate the proposed algorithms on a large set of randomly generated problem instances.

A new framework for time-cost trade-off considering float loss impact

2017 ◽  
Vol 22 (1) ◽  
pp. 20-36 ◽  
Author(s):  
Sameh Monir El-Sayegh ◽  
Rana Al-Haj
Keyword(s):  
Optimization Technique ◽  
Time Cost ◽  
Trade Off ◽  
Deterministic Optimization ◽  
Content Type ◽  
Project Duration ◽  
Trade Offs ◽  
Project Objectives ◽  
The Impact ◽  
New Framework

Purpose The purpose of this paper is to propose a new framework for time–cost trade-off. The new framework provides the optimum time–cost value taking into account the float loss impact. Design/methodology/approach The stochastic framework uses Monte Carlo Simulation to calculate the effect of float loss on risk. This is later translated into an added cost to the trade-off problem. Five examples, from literature, are solved using the proposed framework to test the applicability of the developed framework. Findings The results confirmed the research hypothesis that the new optimum solution will be at a higher duration and cost but at a lower risk compared to traditional methods. The probabilities of finishing the project on time using the developed framework in all five cases were better than those using the classical deterministic optimization technique. Originality/value The objective of time–cost trade-off is to determine the optimum project duration corresponding to the minimum total cost. Time–cost trade-off techniques result in reducing the available float for noncritical activities and thus increasing the schedule risks. Existing deterministic optimization technique does not consider the impact of the float loss within the noncritical activities when the project duration is being crashed. The new framework allows project managers to exercise new trade-offs between time, cost and risk which will ultimately improve the chances of achieving project objectives.

scholarly journals A NEW ANALYTICAL METHODOLOGY TO HANDLE TIME-COST TRADE-OFF PROBLEM WITH CONSIDERING QUALITY LOSS COST UNDER INTERVAL-VALUED FUZZY UNCERTAINTY

2019 ◽  
Vol 25 (2) ◽  
pp. 277-299 ◽  
Author(s):  
Mohammad Hossein Haghighi ◽  
Seyed Meysam Mousavi ◽  
Jurgita Antuchevičienė ◽  
Vahid Mohagheghi
Keyword(s):  
Critical Path ◽  
Quality Loss ◽  
Time Cost ◽  
Analytical Methodology ◽  
New Approach ◽  
Trade Off ◽  
Trade Offs ◽  
And Performance ◽  
Interval Valued

This paper proposes a new framework in addressing time-cost trade-off problem (TCTP) under uncertainty. First critical path analysis is carried out based on developing a new interval-valued fuzzy (IVF)-program evaluation and review technique (PERT) approach. Then, non-conformance risks that influence on execution quality of activities are identified and evaluated based on a new approach that considers probability of risk along with impacts on time, cost, and performance. Then, a new mathematical model under IVF uncertainty is presented to decrease project total time while considering time, cost and quality loss cost that is determined in form of rework or modification cost. Finally, the approach categorizes the activities in three groups based on their level of criticality. Outcome of this methodology is a scheduling that addresses time, cost and quality trade-offs in addition to categorizing activities in different groups based on being on the critical path. Therefore, the project manager not only gets a scheduling based on the TCTP with considering quality loss cost but also has a knowledge of activities that require extra attentions. To show the steps of this methodology, an existing application from the literature is adopted and solved.

scholarly journals PERCEPATAN WAKTU PELAKSANAAN PEKERJAAN KONSTRUKSI DENGAN METODE CPM DAN TCTO

2019 ◽  
Vol 11 (1) ◽  
pp. 33-40
Author(s):  
Cut Zukhrina Oktaviani ◽  
Ibnu Abbas Majid ◽  
Risdiawati Risdiawati
Keyword(s):  
Completion Time ◽  
Construction Projects ◽  
Critical Path ◽  
Minimum Cost ◽  
Time Cost ◽  
Trade Off ◽  
Project Duration ◽  
Project Completion ◽  
Project Costs ◽  
Total Project

Construction delays are a common and major concern in most construction projects. Construction project delay can indirectly affect of project performance. Delay resolve method is to schedule crashing with various methods. This crashing planning is done by combining the Critical Path Method (CPM) and Time-Cost Trade-Off (TCTO) method for the minimum cost in crash duration calculation. Project A data is used to be a case studi in crash duration calculation and costs increase. Rescheduling with CPM result project completion time 120 days and after crashing project duration becomes 94 days, there was a reduction 26 days project completion time. Crashing programme are do to 18 activities from 30 critical activies rescheduling with CPM result. Total project costs changes is Rp. 19.923.466,- due working time addition (overtime) to reduce project time with Time Cost Trade Off method. Normal condition project costs is Rp. 985,171,182.52 and after duration crash becomes Rp. 1,005,094,648, -.

Time–cost–quality trade-off analysis for planning construction projects

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tianqi Wang ◽  
Moatassem Abdallah ◽  
Caroline Clevenger ◽  
Shahryar Monghasemi
Keyword(s):  
Optimization Model ◽  
Construction Projects ◽  
Present Model ◽  
Construction Project ◽  
Time Cost ◽  
Trade Off ◽  
Content Type ◽  
Project Duration ◽  
Trade Offs ◽  
Project Objectives

Purpose Achieving project objectives in constructionprojects such as time, cost and quality is a challenging task. Minimizing project cost often results in additional project duration and might jeopardize quality, and minimizing project duration often results in additional cost and might jeopardize quality. Also, increasing construction quality often results in additional cost and time. The purpose of this paper is to identify and analyze trade-offs among the project objectives of time, cost and quality. Design/methodology/approach The optimization model adopted a quantitative research method and is developed in two main steps formulation step that focuses on identifying model decision variables and formulating objective functions, and implementation step that executes the model computations using multi-objective optimization of Non-Dominated Sorting Genetic Algorithms to identify the aforementioned trade-offs, and codes the model using python. The model performance is verified and tested using a case study of construction project consisting of 20 activities. Findings The model was able to show practical and needed value for construction managers by identifying various trade-off solutions between the project objectives of time, cost and quality. For example, the model was able to identify the shortest project duration at 84 days while keeping cost under $440,000 and quality higher than 85 percent. However, with an additional budget of $20,000 (4.5 percent increase), the quality can be increased to 0.935 (8.5 percent improvement). Research limitations/implications The present research work is limited to project objectives of time, cost and quality. Future expansion of the model will focus on additional project objectives such as safety and sustainability. Furthermore, new optimization models can be developed for construction projects with repetitive nature such as roads, tunnels and high rise buildings. Practical implications The present model advances existing research in planning construction projects efficiently and achieving important project objectives. On the practical side, the optimization model will support the construction industry by allowing construction managers to identify the highest quality to deliver a construction project within specified budget and duration, lowest cost for specified duration and quality or shortest duration for specified budget and quality. Originality/value The present model introduces new and innovative method of increasing working hours per day and number of working days per shift while analyzing labor working efficiency and overtime rate to identify optimal trade-offs among important project objectives of time, cost and quality.

STUDI ANALISIS BIAYA DAN WAKTU MENGGUNAKAN METODE TIME COST TRADE OFF (TCTO) PADA PROYEK TELKOM MANYAR-SURABAYA.

EXTRAPOLASI ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 20-29
Author(s):  
Rizal Rosyid ◽  
Gede Sarya ◽  
Michella Beatrix ◽  
Wateno Oetomo
Keyword(s):  
Critical Path ◽  
Working Hours ◽  
Time Cost ◽  
Time Duration ◽  
Project Cost ◽  
Trade Off ◽  
Project Duration ◽  
Network Diagram ◽  
Schedule Compression ◽  
Normal Duration

AbstractTime cost trade off is a schedule compression to get projects that are more profitable in terms of time (duration), costs, and income. The aim is to compress the project to an acceptable duration and minimize the total project cost. The reduction in project duration is done by selecting certain activities. The analysis begins by preparing a network diagram (network diagram) using Microsoft Project. After that the crashing process is done using the addition of workers and additional hours of work contained in the critical path. Next do the calculations with the time cost trade off method to find the value of the crash cost and cost slope contained in the critical path. From the results of the analysis, the normal duration of the project is 639 calendar days after the process of crashing, adding work hours to 622 days and labor to 623 calendar days and the initial project cost of Rp. 250,320,084,731 after the process of crashing activities with an alternative addition to labor obtained a fee of Rp. 250,559,140,422 and additional working hours in the amount of Rp. 252,734,398,495. So that it can be concluded with the time cost trade off method there is a reduction in the duration and increase in costs.AbstrakTime cost trade off merupakan kompresi jadwal untuk mendapatkan proyek yang lebih menguntungkan dari segi waktu (durasi), biaya, dan pendapatan. Tujuannya adalah memampatkan proyek dengan durasi yang dapat diterima dan meminimalisasi biaya total proyek. Pengurangan durasi proyek dilakukan dengan memilih aktivitas tertentu. Analisa dimulai dengan melakukan penyusunan jaringan kerja ( network diagram ) dengan menggunakan microsoft project. Setelah itu dilakukan proses crashing menggunakan penambahan pekerja dan penambahan jam kerja yang terdapat pada jalur kritis. Selanjutnya melakukan perhitungan dengan metode time cost trade off untuk mencari nilai crash cost dan cost slope yang terdapat pada jalur kritis. Dari hasil analisa yang dilakukan diperoleh durasi proyek normal 639 hari kalender setelah dilakukan proses crashing kegiatan penambahan jam kerja menjadi 622 Hari dan tenaga kerja menjadi 623 hari kalender dan biaya proyek awal sebesar Rp. 250.320.084.731 setelah dilakukan proses crashing kegiatan dengan alternatif penambahan tenaga kerja diperoleh biaya sebesar Rp. 250.559.140.422 dan penambahan jam kerja sebesar Rp. 252,734,398,495. Sehingga dapat disimpulkan dengan metode time cost trade off terjadi pengurangan durasi dan peningkatan biaya. 

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