Design Changes in Construction Projects – Causes and Impact on the Cost

Isolation of design phase from construction has made the design changes inevitable in construction projects. Extensive literature appraisal has acknowledged the detrimental effect of design changes on project performances. However, the impact and causes of design changes have been divided up, either separately or project specific. As a result, the relationship between impact and causes of design changes could not be established for general construction. The primary objective of this paper is to examine the impact of design changes on project cost and identifying actions responsible for these changes. The objectives of the study were achieved through a systematic review of past literature published in well-established journals, and contents analyzed. From the extensive literature review, it was established that the design change is one of the predominant factors to cost overrun, and in some cases, may upshot into cost overrun between 5 and 40% of the project cost. Also, many causes of design changes resulting in cost overrun within the perspective of the owner, consultant, and contractors are explored. Some projects experienced closure as a result of owner induced design changes, although these changes may not be significant in number.  Design changes as a result of consultants and contractors in some cases might have reduced impact but are frequent. For each consideration, most events leading to design changes can be eliminated by improving on communication and coordination between stakeholders. The main contribution of this research is to bring together the impact and causes of design changes on cost under one platform for effectively managing the design process

Estimating annual average daily traffic (AADT) data on low-volume roads with the cokriging technique and census/population data [version 2; peer review: 1 approved, 2 approved with reservations]

Background: Geostatistics focuses on spatial or spatiotemporal datasets. Geostatistics was initially developed to generate probability distribution predictions of ore grade in the mining industry; however, it has been successfully applied in diverse scientific disciplines. This technique includes univariate, multivariate, and simulations. Kriging geostatistical methods, simple, ordinary, and universal Kriging, are not multivariate models in the usual statistical function. Notwithstanding, simple, ordinary, and universal kriging techniques utilize random function models that include unlimited random variables while modeling one attribute. The coKriging technique is a multivariate estimation method that simultaneously models two or more attributes defined with the same domains as coregionalization. Objective: This study investigates the impact of populations on traffic volumes as a variable. The additional variable determines the strength or accuracy obtained when data integration is adopted. In addition, this is to help improve the estimation of annual average daily traffic (AADT). Methods Procedures, Process: The investigation adopts the coKriging technique with AADT data from 2009 to 2016 from  Montana, Minnesota, and Washington as primary attributes and population as a controlling factor (second variable). CK is implemented for this study after reviewing the literature and work completed by comparing it with other geostatistical methods. Results, Observations, and Conclusions: The Investigation employed two variables. The data integration methods employed in CK yield more reliable models because their strength is drawn from multiple variables. The cross-validation results of the model types explored with the CK technique successfully evaluate the interpolation technique's performance and help select optimal models for each state. The results from Montana and Minnesota models accurately represent the states' traffic and population density. The Washington model had a few exceptions. However, the secondary attribute helped yield an accurate interpretation. Consequently, the impact of tourism, shopping, recreation centers, and possible transiting patterns throughout the state is worth exploring

Mitigating schedule overruns in Pre-Stressed girder bridge Construction: Assessing risks and proposing mitigation strategies

Purpose: The paper discusses the critical importance of understanding and managing risks associated with the construction of pre-stressed girder bridges. As a result, it aims to assess, analyze, and propose strategies to mitigate various risk factors contributing to delays and schedule overruns in bridge construction projects. Methodology: These risk risks through literature review and interviews with stakeholders engaged in bridge projects in Pakistan, highlighting the need for activity-specific risk analysis rather than general assumptions. Results: The findings show that 74% of the identified risks can be effectively managed through suitable risk management strategies. Additionally, it was suggested that 17% of the risks should be transferred, while 9% of the identified risks must be retained without any mitigation measures. This survey not only confirmed risks already identified in existing literature but also brought to light new risks previously unnoticed. Moreover, the results highlighted significant differences in risk severity among various project activities. This underscores the necessity for conducting activity-specific risk analysis instead of depending on generalized assumptions for the entire bridge construction project. Conclusions: Among all bridge construction activities, piling emerged as the most high-risk activity, while girder installation was deemed the least risky. Based on this assessment, a set of guidelines aim to mitigate these risks and serve as a reference for minimizing schedule overruns in bridge construction, providing valuable insights for bridge constructors to effectively manage risks