Time-cost Tradeoff Research Articles

Model Time-Cost Trade-Off pada Pekerjaan Tangga Beton Di Banda Aceh

The construction project is very dependent on the project management process, both costs and time. In the implementation process, the service provider must complete one job before doing the next work. Addressing this problem requires a method that is accelerated. The purpose of this study is to do time-cost trade-off modeling. The model wa devoloped from respondent’s perceptions through filling out questionnaires and RAB data. Respondents in study ware directors, estimators and project manager at construction companies domiciled in Banda Aceh. The results showed that ladder work can be broken down into formwork, cleaning and casting. Based oo sub-activities, ladder work can be accelerated from the normal duration of the projectwith the maximum additional cost arisisng from the acceleration of the duration of the ladder work is Rp. 14.109.984,07 (22,13% of normal costs), the maximum additional cost incurred due to the acceleration of the duration of the casting work is Rp. 12.144.740,00 ((18,78% of normal costs) and the maximum additional cost incurred due to the acceleration of the duration of the formwork work is Rp. 12.331.359,00 (19,64% of normal costs). Additional costs per day vary for work items on the stairs because the time-cost trade-off model is non-linear.

A Time–Cost Tradeoff Problem with Multiple Assessments and Release Times on a Chain Precedence Graph

We consider two variants of a time–cost tradeoff problem with multiple assessments on a chain precedence graph. Furthermore, each job can only be started after a release time, and a penalty cost is incurred when a job is not finished before its due date. The motivation is from the project such that a project owner can control the duration of each job and the support level of each project partner to avoid the penalty cost from the tardy jobs. We describe the penalty costs of the first and the second variants as the total weighted number of tardy jobs and the total weighted tardiness, respectively. These can be avoided by compressing the processing times or advancing the release times, which incurs a compression cost or release cost according to the linear and the piecewise constant functions, respectively. The objective is to minimize the total penalty, compression cost and release cost. In this paper, we propose the procedure based on the reduction to a shortest path problem, and show that the procedure can solve two variants in strongly polynomial time.

Time-cost optimization in repetitive project scheduling with limited resources

PurposeThe purpose of this research is to develop a time-cost optimization model to schedule repetitive projects while considering limited resource availability.Design/methodology/approachThe model is based on the constraint programming (CP) framework; it integrates multiple scheduling characteristics of repetitive activities such as continuous or fragmented execution, atypical activities and coexistence of different modes in an activity. To improve project performance while avoiding inefficient hiring and firing conditions, the strategy of bidirectional acceleration is presented and implemented, which requires keeping regular changes in the execution modes between successive subactivities in the same activity.FindingsTwo case studies involving a real residential building construction project and a hotel refurbishing project are used to demonstrate the application of the proposed model based on four different scenarios. The results show that (1) the CP model has great advantages in terms of solving speed and solution quality than its equivalent mathematical model, (2) higher project performance can be obtained compared to using previously developed models and (3) the model can be easily replicated or even modified to enable multicrew implementation.Originality/valueThe original contribution of this research is presenting a novel CP-based repetitive scheduling optimization model to solve the multimode resource-constrained time-cost tradeoff problem of repetitive projects. The model has the capability of minimizing the project total cost that is composed of direct costs, indirect costs, early completion incentives and late completion penalties.

Time–cost trade-off in a multi-choice assignment problem

ABSTRACT The conventional assignment problem is unable to handle scenarios that may arise due to different working modes of machines leading to multiple cost and time entries corresponding to a job–machine pair. The present article deals with this problem and models it as a multi-choice bi-objective assignment problem, the two objectives being assignment cost and bottleneck time. Two different solution procedures are presented based on the Decision-Maker's (DM's) preference structure. First, when the DM provides his/her preference structure as goals, a solution methodology is proposed using goal programming and its different multi-choice variants. In the second case, when no preference is provided by the DM, a two-step approach is presented that iteratively solves a multi-choice cost-minimizing assignment problem to obtain all Pareto-optimal time–cost pairs and finally, based on the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS), a single efficient pair is obtained. The algorithm is successfully implemented using the CPLEX ® optimization package and tested on various test problems.

Robust Emergency Relief Supply Planning for Foreseen Disasters Under Evacuation-Side Uncertainty

For foreseen natural disasters (e.g., hurricanes or floods), the uncertainties faced in relief logistics primarily stem from evacuation activities. We present a strategic planning problem to supply relief items by considering uncertainties in disaster location, intensity, duration, and evacuee compliance. To ensure time- and cost-effectiveness in relief distribution, we develop a robust optimization model to determine centralized supply locations, and supply quantities for different transportation modes in a five-tier network. In doing so, we consider the interaction between evacuation and supply-side activities and capture the inherent uncertainties using a combination of event and box uncertainty representations. Our model provides a decision maker with the flexibility of including or excluding the time dependency of evacuation-related uncertainties. Accordingly, it suggests a threshold time window for relief distribution, beyond which either the system cost increases or the benefits of early distribution diminish. Although the model primarily aids a policymaker in strategic preparedness, its tactical variant can aid the efficient distribution. We devise an enhanced Benders decomposition-based efficient solution method to solve realistic-size problems. In a case study using geographic information system data, we highlight the complex dynamics among various system components and discuss the resulting time-cost trade-offs that also influence the network structure.

Designing project schedule using crashing method to compress the fiber to the home project schedule

ABC Company is an agent of network construction, operation, and maintenance. ABC Company is currently implementing the STTF (Shit to the Front) project, which is the project to add FTTH (Fiber to the Home) networks in areas that can have high customer demand. One of the STTF project construction sites is the Indra Prahasta II housing location. However, the project is currently experiencing work delays due to the Covid-19 disaster in Indonesia. Delays in project execution can result in potential prospects choosing another company that provides similar services. The project schedule can be accelerated using the crashing method and TCTO (Time Cost Trade-Off) analysis to solve this problem. This research's acceleration will be carried out with alternatives for adding 3 hours, 2 hours, 1 hour, and an alternative to increasing workers' number. This project has an average duration of 55 working days with a total cost of Rp 604,124,460. The results obtained from data processing, on the alternative of adding 1 hour of overtime work, the total duration becomes 54 working days with total project cost is Rp 605,734,138. In addition to 2 hours of overtime work, the project's total duration can be reduced to 54 days with a total project cost Rp 606,803,619. And for the addition of 3 hours overtime, the total duration can be shortened to 54 days with a total cost of Rp 606,803,619. As for increasing the number of workers, project work duration can be shortened to 54 working days with a total project cost Rp 604,556,748

PERCEPATAN JADWAL KONSTRUKSI DAN PENGARUHNYA TERHADAP BIAYA PENYELESAIAN PROYEK KONSTRUKSI

Means of transportation at present is very important to continue to be built effectively and efficiently to the level of fluency and accuracy of time toward the goal easier and faster and to meet minimum service standards of the highway. In line with that so that the toll road remain in the minimum service standards need to be additional road capacity to effectively and efficiently for that it is necessary to study whether the possible acceleration of road capacity expansion projects, so that the level of minimum service standards can be maintained and to what extent the effect of accelerating the schedule project on development costs.One method that can be used to analyze the effect of accelerating the project towards the costs is to analyze the exchange of money and time (time cost trade off).Variables used in the calculation of "Acceleration Schedule of Construction and Completion Costs Effect on Construction Project "is the direct labor, equipment, overtime working hours, method of construction, all have an influence on the different costs, acceleration (crash) or compression of time that have done the job and the biggest costs related to the work that has the greatest cost , a benefit if the toll road opened in advance of the acceleration due to a smaller project compared to the costs required for expediting the project construction on this project, based on the cost of the acceleration is not necessary because the costs to perform a greater acceleration when compared with a benefit.

Automated BIM schedule generation approach for solving time–cost trade-off problems

PurposeNowadays, building information modeling (BIM) represents an evolution in the architecture, engineering and construction (AEC) industries with its various applications. BIM is capable to store huge amounts of information related to buildings which can be leveraged in several areas such as quantity takeoff, scheduling, sustainability and facility management. The main objective of this research is to establish a model for automated schedule generation using BIM and to solve the time–cost trade-off problem (TCTP) resulting from the various scenarios offered to the user.Design/methodology/approachA model is developed to use the quantities exported from a BIM platform, then generate construction activities, calculate the duration of each activity and finally the logic/sequence is applied in order to link the activities together. Then, multiobjective optimization is performed using nondominated sorting genetic algorithm (NSGA-II) in order to provide the most feasible solutions considering project duration and cost. The researchers opted NSGA-II because it is one of the well-known and credible algorithms that have been used in many applications, and its performances were tested in several comparative studies.FindingsThe proposed model is capable to select the near-optimum scenario for the project and export it to Primavera software. A case study is worked to demonstrate the use of the proposed model and illustrate its main features.Originality/valueThe proposed model can provide a simple and user-friendly model for automated schedule generation of construction projects. In addition, opportunities related to the interface between an automated schedule generation model and Primavera software are enabled as Primavera is one of the most popular and common schedule software solutions in the construction industry. Furthermore, it allows importing data from MS Excel, which is used to store activities data in the different scenarios. In addition, there are numerous solutions, each one corresponds to a certain duration and cost according to the performance factor which often reflects the number of crews assigned to the activity and/or construction method.

Universal distribution of batch completion times and time-cost tradeoff in a production line with arbitrary buffer size

We study the distribution of batch completion times in a serial line of processing stations with a finite buffer—a flow shop. Batch completion times in these lines are distributed according to the Tracy-Widom type 2 distribution from random matrix theory when there is no limitation on buffer size, and all processing durations are identically and exponentially distributed. We significantly extend this result to the case of finite and inhomogeneous buffers and general distributions of processing durations. Using numerically exact computation, we demonstrate the Tracy-Widom distribution matches the observed distribution of batch completion times even when the size of the buffer is finite or inhomogeneous or the distribution of processing durations differs from exponential. This universality is explained by observing that asymptotically batch completion times can be described by directed last passage percolation on the plane, a process whose asymptotic limit falls in the Tracy-Widom universality class. A generic tradeoff is found between the cost of the work-in-process and the average batch completion time, which arises because small buffers cost less but cause more blocking while large buffers are costly but cause less blocking. The maximal improvement in average batch completion time is bounded by ∼12 percent for a line with many exponential processing stations. In this case a small increase in the size of the buffers is sufficient for reaching the unlimited buffer regime. More generally, we found that the maximal improvement monotonically increases with the coefficient of variation of the processing duration distribution.

Analysis of Time Comparison and Costs of Implementing Road Implementation with Time Cost Trade-Off Method

Project for the construction of the Gunungsari Banjar Sugihan - Kandangan diversion channel, Surabaya, in the implementation of this project there was a delay in how many works. One way to anticipate this delay is by accelerating it using the Time Cost Tread Off method, through alternative working hours (overtime) and additional labor. The method is used so that the project can run smoothly and so that the project can be accelerated in completion. Time-Cost Trade-Off analysis, better known as TCTO. jobs included in the critical cross and jobs that are not allowed to delay are as follows: Urugan Sirtu (solid), Lean concrete fc 10 Mpa work, Rigid pavement fc 30 Mpa work finishing growing, iron beginning work.

Factors Affecting Improved Project Performance Using Lean Six Sigma Methods and Time Cost Trade Off for the Ammunition Warehouse Projectof Indonesia

Factors Affecting Improved Project Performance Using Lean Six Sigma Methods and Time Cost Trade Off for the Ammunition Warehouse Projectof Indonesia

Cost Optimization in Building Construction Projects with Special Reference to Kathmandu Valley of Nepal

Cost optimization is a process that should be carried out throughout the construction period to ensure that the cost of the project is within an allotted budget. Time and cost are the two most significant factors in any construction project. Cost increases with the time of construction. The objective of this study was to find out the factors that contribute to the optimization of construction costs in building construction projects in Nepal. The study was conducted during the period from April 2019 to September 2020. Field observation, in-depth interviews, focus group discussions and questionnaire surveys were the major tools for the investigation of this study. The findings were analyzed in nine categories: project related factors, design related factors, owner related factors, consultant related factors, contractor related factors, material related factors, labor related factors, equipment related factors, and external factors. The study found some key factors related to time and cost overrun, optimizing cost of construction and the strategies to optimize project costs. The most important strategy to optimize the construction cost are effective cost planning and control, development of proper monitoring and tracking system, sound working environment, recording daily work progress, using time cost trade off, follow plan-do-check-act quality policy, hire skilled labor and effective supervision. The study suggests that constructability and value engineering principles should be adopted in construction projects.

An Integrated Multi-Criterion Decision-Making Analysis to Rank the Pareto-Front Solutions of Time-Cost Trade-Off Problems

In the construction management planning, both the client and the contractor are interested in completing the project within the planned schedule. To achieve it, time-cost trade-off problem (TCTP) is carried-out to obtain the optimal set of time-cost alternatives. Although Pareto front solutions are not preferred to each other, the decision-maker (DM) has to choose only the best solution. The DMs are neither well-educated nor have adequate knowledge to make proper decisions. Thus, such a choice has to be made through additional preferences not included in the original formulation of the optimization problem. To better support the meta-heuristic optimization outputs, in this paper, an integration of entropy weight, simple additive weighting (SAW), and technique for order of preference by similarity to ideal solution (TOPSIS) are modelled to solve the MCDM problem, while the Teaching Learning Based Optimization (TLBO) algorithm is applied to solve the proposed multi-objective decision-making model. In the proposed model, the weights selections are done objectively to demonstrate the variation on the rankings of MCDM approaches. While the entropy technique served to determine the weight of the criteria from the original matrix data objectively and the TOPSIS method is employed to rank the alternative Pareto front solutions. The proposed methodology is utilized to rank a set of Pareto optimal solutions of well-known optimization problems. The obtained results are compared against the rankings provided by (SAW) approach to investigate the efficiency of the proposed model. Results demonstrate that the present model can be a favorable decision-making model for the decision-makers.

Service for optimization of charging stations selection for electric vehicles users during long distances drives: time-cost tradeoff

One of the weighty curb to electric vehicles (EV) acceptability is their constraints when performing long-distance trips. Even if improvements made on fast charging technology enable to recover up to 300 km range in 20 minutes, the low density of this kind of infrastructure and the variability in their availability can lead to significant waiting times for users. In this context, it is useful to provide users with information about the availability of charging stations to facilitate the use of EVs. In this article, we present a vehicle/infrastructure communication system. EVs ask charging stations for estimated waiting times at a specific time. Stations calculate these estimates based on notifications of intention to charge received from other vehicles. Thanks to this information, vehicles will be able to optimize their journey. This system has the advantages of being easily scalable because it is distributed, simple and only require the sharing of little personal information. However, the stations on the route may have different charging powers and prices. This raises the question of the criteria for optimizing these trips, depending on whether users favor the cost or the duration of the trip. In this article, we examine this tradeoff using multi-objective optimization and Pareto fronts, as well as the impact of such a communication system on recharge decisions.

Integrating Quality and Safety in Construction Scheduling Time-Cost Trade-Off Model

AbstractQuality and safety are important and are the leading concerns in a construction project. Planning a project without properly incorporating these two performance parameters propagates multif...

Latin hypercube sampling-based NSGA-III optimization model for multimode resource constrained time–cost–quality–safety trade-off in construction projects

Many researchers have paid significant amount of attention for the development of time-cost, time-cost-quality and time–cost–safety trade-off optimization models. However, there is still a need to integrate the quality and safety together in time–cost trade-off optimization. To fill this gap, considering the multimode activities in project, this paper presents a multimode resource-constrained time–cost–quality–safety trade-off optimization model. Besides, this study considered the limited availability of resources for each execution mode of activities. A population-based meta-heuristics approach the nondominated sorting genetic algorithm III (NSGA III) is employed to develop the model. Also, Latin hypercube sampling for population initialization, analytical hierarchy process for quality determination and fuzzy logic for safety parameters determination are used. A case study of building construction project is used to demonstrate the applicability of proposed model. Whereas, the measure of various performance metrics and comparisons with existing trade-off optimization models demonstrate the effectiveness of proposed model in simultaneous optimization of four objectives. Moreover, a value path plot is prepared for the visualization of more than three objectives and a priori approach is presented to select one solution from obtained Pareto-optimal front.

A multi-agent based cooperative approach to decentralized multi-project scheduling and resource allocation

While project crashing is a prominent practice in project management and can be approached by the well-known time–cost tradeoff problem (TCTP), the existing methodologies assume a centralized decision paradigm. In this paper, we study a new decentralized multi-project time-cost tradeoff problem, called MPTCTP-D, where project scheduling and resource allocation decisions are made in a distributed way by autonomous project managers to optimize their local objective, subject to a global available budget for all the projects. We show and prove the existence of price of anarchy as the difference between the optimal objective value of MPTCTP-D and its centralized counterpart. A multi-agent based cooperative approach with negotiation protocol is proposed to mitigate resource competition of autonomous local decisions and achieve a reasonable allocation of resource for global decision-maker, with both exact and local-search based heuristic algorithms developed. Our exact algorithm is able to find optimal solutions and prove optimality for instances with up to five projects and 120 activities per project. The hybrid randomized and 2-opt improvement algorithm is able to efficiently find optimal solutions to small instances and significantly better solutions than other heuristics alone for instances with up to 20 projects and 120 activities per project. Managerial insights on the optimal solutions and the price of anarchy are obtained and discussed.

Solving Fuzzy Time–Cost Trade-Off in Construction Projects Using Linear Programming

The time–cost trade-off has been recognized as a very significant aspect of construction management. Generally, time–cost trade-off can be modeled as a fuzzy linear programming problem with symmetric or non-symmetric fuzzy numbers. However, it was successfully solved when the fuzzy membership functions are only symmetric. In the present work, a novel approach is introduced to solve fuzzy linear programming problem with non-symmetric fuzzy membership functions by transforming it to its corresponding nearest symmetric one. The transformed problem is then converted to its crisp linear programming problem and then solved by the standard primal simplex method. Two examples are presented to show the effectiveness of the proposed approach, and the results are discussed.

A Tale of Two Linear Programming Formulations for Crashing Project Networks

Problems associated with time–cost trade-offs in project networks, which are commonly referred to as crashing problems, date back nearly 60 years. Many prominent management science textbooks provide a traditional linear programming (LP) formulation for a classic project crashing problem, in which the time–cost trade-off for each activity is continuous (and linear) over a range of possible completion times. We have found that, for students who are being introduced to time–cost trade-offs and the principles of project crashing, an alternative LP formulation facilitates a greater conceptual understanding. Moreover, the alternative formulation uses only half of the decision variables in the traditional formulation and has fewer constraints for many problems encountered in management science textbooks. Results from an MBA section of operations management suggest that students prefer the alternative formulation. Additionally, we have developed an Excel workbook that generates all possible paths for a network, allows students to manually evaluate crashing decisions, and generates the alternative LP formulation. We demonstrate the workbook using a small synthetic example and a larger, real-world network from the literature. We also show that the alternative formulation can be adapted easily to accommodate discrete project crashing problems for which the time–cost trade-offs for activities are not necessarily linear.

ACT 2 : Time–Cost Tradeoffs from Alternative Contracting Methods

AbstractIncentive/disincentive (I/D) and cost-plus-time (A+B) are two of the most widely used alternative contracting methods (ACMs) for accelerating the construction of highway infrastructure impr...