Duration Of Construction Projects Research Articles

Scheduling Linear Construction Projects with Constraints on Resource Availability

AbstractProduction rates for various activities and overall construction project duration are significantly influenced by crew formation. Crews are composed of available renewable resources. Construction companies tend to reduce the number of permanent employees, which reduces fixed costs, but at the same time limits production capacity. Therefore, construction project planning must be carried out by means of scheduling methods which allow for resource constrains. Authors create a mathematical model for optimized scheduling of linear construction projects with consideration of resources and work continuity constraints. Proposed approach enables user to select optimal crew formation under limited resource supply. This minimizes project duration and improves renewable resource utilization in construction linear projects. This paper presents mixed integer linear programming to model this problem and uses a case study to illustrate it.

Probabilistic Construction Project Duration Prediction Models for High Rise Building Based on Earned Schedule Method in Jakarta

Probabilistic Construction Project Duration Prediction Models for High Rise Building Based on Earned Schedule Method in Jakarta

The Nature, Terms and Legal Effects of Presale or Pre-Construction Contracts of Building (Apartment)

Modern living in present-day in the territory of contracts, as in many other fields, has led to numerous and complex phenomena. One of its manifestations is the construction (constructing) phenomenon and its pre-sale contracts. Sale of the building and apartment units before their construct is a common problem in today's society that it depends on pre-sales or pre-construction contracts. The long duration of construction projects and fluctuations in materials prices, especially considering the today’s economic situation is one of the important reason for the development of pre-sales contracts in Iran. This study has been carried as a descriptive analytical one to examine and identify the nature, conditions (terms) and legal effects of pre-sold or pre-construction contracts and among the results of this study are that; the presale contract of construction (building) despite the fact that sales did not exist at the time of conclusion of the contract, can be considered as the same sale. The producing of ordered goods is the responsibility of artificial maker (manufacturer) and the made should be determined and death and time to deliver the goods must be determined. The determination of price also as determination of made is very important and must be delivered to the makers according to contract.

IMPACT OF BIDDING ENVIRONMENT ON CHANGE ORDERS

Change orders occur during construction, and usually increase both construction cost and project duration. This paper investigates how change orders are related to the bidding environment. The data used in this study were collected from 74 public building construction projects awarded by the Public Building Commission of Chicago in the seven-year period 2008-2015. The contract values range between $0.3-$70 million, and the total worth of the projects is a little over $1.1 billion. While delay may result in liquidated damages for contractors, increase in project cost can cause financial problems for owners. It is in the interest of owners and contractors to study similar past projects, and to observe how change orders are affected by the level of competition in bidding. Owners must budget for contingencies, and contractors must adjust their resources in anticipation of change orders. It would therefore be quite desirable for owners and contractors to be able to predict the dollar amount and duration implications of potential change orders by making use of past historical data. The prediction of the dollar amount and duration implications of potential change orders before the construction starts can alert construction owners and contractors to potential delays in total project completion time and potential overruns in total project cost. Knowledge about potential change orders creates a predictable environment and improves the relationship between owners and contractors. The results of this study indicate that contractor-driven change orders are positively related to the difference between the lowest and the second lowest bids.

Exploring delay causes of road construction projects in Egypt

Construction delays are a common phenomenon in civil engineering projects in Egypt including road construction projects. Therefore, it is essential to study and analyze causes of road construction delays. This paper studied a list of construction delay causes gathered from literature having different types of construction, different countries, different periods and different numbers of delay causes and delay groups. A questionnaire and personal interviews have formed the basis of this paper listing 293 delay causes. The questionnaire survey was distributed to 500 construction participants and 389 were received who represent consultants, contractors and site/design engineers excluding the owner representing the government in road projects as one party only. Relative Importance Index (RII) is calculated and according to the highest values the top twenty and the least twenty delay causes of construction projects in Egypt are determined. A case study is analyzed and compared to the most important delay causes in the paper. The test results reveal good correlation of causes and groups between contractors and site/design engineers and between consultants and site design engineers and a somewhat low correlation between contractors and consultants. So there are no root causes that can be taking for granted to be most or least effective delay causes. Proposed model for predicting actual road construction project duration was developed; a real case study tested the accuracy of proposed model. According to the analysis of case study, the most contributing causes and groups to delays were discussed, and some future recommendations were proposed in order to control and minimize delays in road construction projects. These findings can be helpful for project managers to mitigate the road construction delays in Egypt. In order to effectively overcome the road construction delays in developing countries, suggestions are made for fundamental and large‐scale reforms in procurement systems and stakeholders’ management. Also, this paper is useful for both researchers and road construction parties and allows detailed and repeatable analysis of the progress of a road construction project in order to facilitate and achieve a competitive level of time, cost and quality for effective road construction projects.

MULTIOBJECTIVE OPTIMIZATION MODEL FOR SCHEDULING OF CONSTRUCTION PROJECTS UNDER EXTREME WEATHER

Extreme weather significantly impacts construction schedules and costs and can be a source of schedule de­lays and budget overruns. A multi-objective optimization model, presented herein for the scheduling of construction projects under extreme weather conditions, can generate optimal/near optimal schedules that minimize the time and cost of construction projects in extreme weather regions. The model computations are organized as follows: (1) a scheduling module for developing practical schedules for construction projects, (2) a cost module for computing total project cost, and (3) a multi-objective module for determining optimal/near optimal trade-offs between project time and cost. Two practical examples of the effects of extreme weather on construction time and direct cost are provided, the first of which shows the impact of extreme weather on construction time and cost, and the second of which demonstrates the ability of the model to generate and visually present the optimal trade-offs between the duration and costs of construction projects under extreme weather conditions.

Incorporating Multiskilling and Learning in the Optimization of Crew Composition

AbstractThe presence of multiskilled workers in a crew can increase the crew’s productivity through reducing inefficiencies and supervision requirements, while also providing on-the-job learning opportunities for single-skilled workers. The effect of the presence of multiskilled workers on the learning rate of workers, which is also a function of skill level and experience, and thus on the crew’s productivity, is especially significant in repetitive construction projects. This paper presents a mathematical model for identifying the optimal combination of single-skilled and multiskilled workers with different levels of experience in the crew to minimize the duration of construction projects by accounting for the overlapping effects of multiskilling, skill level, and learning on the crew’s productivity. The model is applied to an illustrative case project to demonstrate the practicality of the model. The optimum crew compositions for different activities involved in the case project are identified using a s...

Repetitive construction processes scheduling using mixed-integer linear programming

Many construction projects contain several identical or similar units, such as floors in multistory buildings, houses in housing developments, sections of pipelines or highways. Repetitive processes arise from the subdivision of a generalized construction process into specific activities associated with particular units. In many cases it is possible to perform individual processes (repeated in each units) in alternative ways (modes). Regardless of the construction project procurement system, duration and cost are the key factors determining project’s economic efficiency and fulfillment of the owner’s needs and requirements. Minimizing project duration and cost are the most important criteria for schedule optimization. Processes that repeat from unit to unit are realized by specialized crews. Uninterrupted resource utilization becomes an extremely important issue for scheduling repetitive processes to minimize employment costs. In this paper, the problem of selecting appropriate modes and minimizing the total project cost and with a constraint on project duration is presented with respect to the continuity of the crews’ work. The paper uses the mixed integer linear programming to model this problem and uses a case study to illustrate it.

건설프로젝트에서 전략적 하도급 방안에 관한연구 : 설계시공병행방식 사례를 중심으로

본 연구는 설계시공병행방식에서의 하도급관리의 중요성 및 필요성을 강조하고, 공사의 특수성과 더불어 성공요인을 살펴보고 하도급와의 관계에 대해 고찰하였으며, 이를 바탕으로 하도급 전략 방안 도출해 실제 공사사례에 적용하였다. 따라서 설계시공병행방식의 실제사례를 통하여 제안한 전략적 하도급방안을 적용해보고 그 효과의 실증했음에 그 의의를 가지나, 대표 표본에 대한 검증이라는 한계점 때문에 더 많은 사례를 통한 검증이 요구된다. Fast-tracking was developed as an optimizing method to shorten the duration of construction project in 1960's, and it introduced to Korea in 1999. Since then, many Korean companies have been used fast-tracking for getting economical benefit from shorten duration. However, there were some problems(dispute, delay and cost overrun) because of using inappropriate subcontractor management system. For this reason, previous studies suggested some management models to solve these problems. Unfortunately, however, the models have been had some doubts about reliability, objectivity and possibility of using them on real construction site. Therefore, this study suggests 3 steps of strategic subcontracting method and apply it on real fast-tracking practice(L company) to secure reliability and objectivity. Through this, the method is expected to make up the doubts of previous studies.

Time-Profit Trade-Off of Construction Projects Under Extreme Weather Conditions

Maximizing the profitability and minimizing the duration of construction projects in extreme weather regions is a challenging objective that is essential for project success. An optimization model is presented herein for the time-profit trade-off analysis of construction projects under extreme weather conditions. The model generates optimal/near optimal schedules that maximize profit and minimize the duration of construction projects in extreme weather regions. The computations in the model are organized into: (1) a scheduling module that develops practical schedules for construction projects, (2) a profit module that computes project costs (direct, indirect, and total) and project profit, and (3) a multi-objective module that determines optimal/near optimal trade-offs between project duration and profit. One example is used to show the impact of extreme weather on construction time and profit. Another example is used to show the model’s ability to generate optimal trade-offs between the time and profit of construction projects under extreme weather conditions.

Probabilistic multiobjective optimization of sustainable engineering design

As the global population reaches 7 billion and standards of living are increasing, engineers are being pressured to use limited natural resources to satisfy ever-increasing demand. Project engineers are currently charged with achieving a balance between cost and duration, and must consider environmental factors to reach sustainable development. This work proposes a novel probabilistic multi-objective optimization algorithm to attain sustainable construction cost, project duration, and CO2 emissions simultaneously in an uncertain project environment. The novel algorithm, which is based on Particle Swarm Optimization integrated with Monte Carlo simulation, is applied to generate a low-carbon economy and cleaner production. A typical construction project is selected to demonstrate the application of proposed algorithm for making sustainable decisions under multi-objectives. The proposed method demonstrated its risk analysis capacity by obtaining non-dominant optimized solutions for cleaner construction. This paper contributes to facilitating project managers in achieving a design that satisfies technical and quality requirements with lowest cost, shortest duration, and minimal adverse impacts on the environment.

SUSTAINABLE GREEN CONSTRUCTION MANAGEMENT: SCHEDULE PERFORMANCE AND IMPROVEMENT

Over the last few years, the green building movement in Singapore has leaped bountifully. While environmental sustainability for greener construction has been emphasized, rare research has been conducted to analyze performance of green construction projects. As a result, this study aims to address schedule performance of green building construction projects and to provide some recommendations that may improve the targeted performance. To achieve this objective, a questionnaire was developed and the responses from 30 companies were analysed, and interviews with 6 project managers were conducted to further supplement and substantiate the survey results. The analysis reported that green building projects required an average of 8% more time than traditional building projects of similar size and characteristics. In addition, on average, these projects were delayed by 4.8% when compared with their as-planned schedules. Lastly, a list of recommendations was also introduced, aiming to ameliorate the schedule performance. This study will offer a benchmark for the industry to gauge the overall duration and performance of green building construction projects.

Model for Evaluating Uncertain Project Duration Considering Construction Interface Problems

Many probabilistic scheduling models have been developed to determine the duration of construction projects. However, these models are not appropriate to capture the effect of the factors that are involved construction interface problems on the durations of multiple activities. This work presents a simulation-based probabilistic scheduling model that includes the impact of construction interface problems on the duration of building projects. The proposed model is established according to an activity duration model and a work-group (WG)-based schedule network. The activity duration model is applied to reflect the effects of general factors on the duration of each activity; the WG-based schedule network is employed to evaluate the effects of construction interface problems on the durations of multiple activities. The results of applying the proposed model to an example project reveal that the duration of a project can be over-optimistically estimated if the effects of construction interface problems are neglected.

Study on the Optimization of Public Construction Project Duration

This article gathers 16 factors which influence the duration of public construction project on the basis of research and analysis, and forms hierarchical relationships and causal relationships of the factors through improved interpretive structural model. Finally, comes up with several recommendations on the issue, further，the research and discussion on public construction project control and optimization of construction duration of our country are carried out.

A Study on Public Construction Project Duration Risk Identification and Evaluation

According to the Intricate Dynamic Relationship of the Duration Management System，the Paper Identified Risk Factors for the Object.Then Established a Comprehensive Integrated Public Construction Project Duration Risk Assessment Model with the Application of Game Theory-Based Weighting Method. the Model is Validated Effective and Reasonable through Simulation Analysis. and it also Provides a New way of Thinking in the Duration Risk Assessment.

THE EFFECT OF CURRENT PUBLIC PROCUREMENT LAW ON DURATION AND COST OF CONSTRUCTION PROJECTS IN TURKEY

The current public procurement law (Law No. 4734) was established in Turkey in 2003. The current law has fundamental differences from the previous one, Law No. 2886, in that the current law's main objective is to increase the effective use of public resources. Although the current law was enacted nine years ago, no in-depth research has been undertaken related to the extent of public savings. Thus, the aim of this research is to analyze the performance of public investments for construction with respect to their success in achieving on time and within budget completion. Additionally, a comparison between the completion duration and budget of construction projects undertaken under the current and the previous law is presented. To achieve these goals, historical contract documents addressing 878 and 575 public construction projects undertaken under two laws, respectively, were analyzed. In this context, the data mining method, including decision trees, artificial neural network, and support vector machines, was applied to predict the duration and cost deviations of the construction projects during the tender process, and the results were compared. It was demonstrated that the current law has contributed substantially towards the completion of the projects within estimated or envisaged durations and costs. The findings of this research can be generalized to countries with similar economical and organizational structures with Turkey.

Calculation Method of the Uncertainty Duration of Construction Projects

The duration of construction project is of great uncertainty because the construction project is of large scale, its construction cycle is long, it takes much consumption in material resources, human and financial resources, it is of complicated cases, and there are also many unpredictable factors. A method to determine the uncertainty duration whose chief path is not a single one is raised combining with engineering practices in this thesis.

Factors Influencing the Duration of Road Construction Projects in Sri Lanka

This study attempts to reveal the factors influencing the duration of road construction projects in Sri Lanka, and to identify how delays can be mitigated. The emphasis here is limited to study the Contractor's point of view. The main concern of the study is to identify the nature of the population (Road projects in Sri Lanka) using Statistical Inference. The other focusing areas are to identify Main Causes of Delay & Delay Diversification, and Delay Mitigation. This study defines the Percentage Delay parameter and the Relative Significance Index (RSI) model, which are the new concepts introduced by the author this study. The preliminary data for this research have been collected through a literature review and a questionnaire survey targeted at local contractors of Road Construction. The collected data yields a high reliability coefficient, which is 90%. This study reveals that the local road construction projects experience 56 % - 88 % of average time overrun compared to the original (planned) project duration. The findings further illustrate that the financial problems of the Owner as well as of the Contractor, is the most influencing factor causing delays in road construction projects in Sri Lanka.

Multi‐objective particle swarm optimization for construction time‐cost tradeoff problems

Reduction in construction project duration is generally linked to additional cost due to more expensive resources required. Hence tradeoff between time and cost is crucial to the efficiency of a construction project. The time‐cost tradeoff (TCT) issue has been studied through various multi‐objective optimization methodologies to determine an optimal set of activity methods with the objectives of minimizing project duration and total cost. A multi‐objective particle swarm optimization that adopts a combined scheme for determining the global best of each particle is presented for solving the TCT problem. The candidate TCT solutions in terms of a set of construction methods for activities are represented through the multidimensional particles. The framework of the combined scheme‐based multi‐objective particle swarm optimization (CSMOPSO) is developed. Computational analyses are conducted to investigate the performance of the CSMOPSO, including comparison with other methods. This study is expected to provide an alternative solving methodology for the TCT problem and help contractors or engineers plan construction methods with optimal time–cost tradeoff.

Forecasting final budget and duration of highway construction projects

PurposeThe purpose of this paper is to develop models to forecast final budget and duration of a highway construction project during construction stage.Design/methodology/approachHighway construction project data are collected and analyzed to find out factors affecting project final budget and duration before developing the forecasting models, research for which is based on the principle of Artificial Neural Network (ANN). The forecasting results obtained from the proposed method are compared with those obtained from the current method based on earned value.FindingsFactors affecting final budget and duration are presented. The forecasting results obtained from the proposed method based on ANN application are more accurate and stable than those obtained from the current method based on earned value.Research limitations/implicationsFactors affecting final budget and duration may differ if applied in other countries, since the project data were collected in the Kingdom of Thailand. The forecasting models, therefore, must be reconsidered for better outcomes.Practical implicationsThe study presents a useful tool for the highway construction project manager to predict project final budget and duration. The results can potentially provide early warning of over‐budget and schedule delay.Originality/valueThe ANN models to forecast final budget and duration of highway construction projects during the construction stage, developed by using project data reflecting continual and seasonal cycle data, can provide better predicting results.