sustainability Article Toward Reducing Construction Project Delivery Time under Limited Resources Hossam H. Mohamed 1 , Ahmed H. Ibrahim 1 and Asmaa A. Soliman 2, *   Citation: Mohamed, H.H.; Ibrahim, A.H.; Soliman, A.A. Toward Reducing Construction Project Delivery Time under Limited Resources. Sustainability 2021, 13, 11035. https://doi.org/10.3390/su 131911035 Academic Editor: Carlos Oliveira Cruz Received: 10 September 2021 Accepted: 28 September 2021 Published: 5 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Construction Engineering & Utilities Department, Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt; Hosny_Hosm@yahoo.com (H.H.M.); mekky69@yahoo.com (A.H.I.) 2 Civil Engineering Department, Higher Technological Institute (H.T.I), 10th of Ramadan City 44629, Egypt * Correspondence: Asmaa.soliman@hti.edu.eg Abstract: One of the most vital construction project aspects is to complete a project in minimum time restricted to the time–cost trade-off. Overlapping activities’ planning and their impact on the project under limited resource constraints should be considered. This study aims to develop a model for optimizing the project schedule and cost regarding overlap activities and their impacts. This study reviews previous studies on changes in past activities likely to produce additional reworking of subsequent activities. In addition, an AHP model is developed to assess the reworking time of subsequent activities based on possible changes in previous activities. In addition, five realistic construction projects are applied. Finally, an optimizing model is developed for optimizing project time and cost using overlapping techniques by using the Java program. The results indicate that the proposed model can be used by project managers easily for solving time and cost optimization problems. In addition, it can be updated to continuously improve its functionality. Finally, it can be updated later to support AI for finding better solutions. Keywords: fast-tracking; AHP; rework time; Java; construction schedule 1. Introduction Rework in construction projects is a widespread problem that affects project perfor- mance negatively. First, it is necessary to clarify the definition of reworking, because how it is defined helps to find solutions and reduce risks [1]. Love et al. [2] defined rework as the unnecessary effort to re-implement a process or activity incorrectly carried out the first time regardless of any changes in project scope or design that might lead to additional work. Enshassi et al. [3] defined rework as a serious problem in construction projects in the Gaza Strip, which was one of the main reasons for the delays in schedule and increased construction costs, besides customer dissatisfaction. There are various definitions of re- work in the construction management literature, which mainly include quality deviations, quality failures, defects, and non-conformance. Martins et al. [4] introduced a model using cluster analysis to classify risks. Risks are classified according to different risk categories, activity development, sensitivity, production reliability, and constraints on construction projects. The delay in the schedule was defined as completing the construction project after the specified date. This delay is often accompanied by cost overruns. Delays in the schedule include location conditions, slow approval of work permits, design errors, delays in funding and progress payments, owner intervention, improper planning, inadequate subcontractors, and source change orders [5]. Cheng and Darsa [6] developed an ANN model to predict the time delay in a project. Identifying the most important factors affecting a project could reduce delays in the construction schedule. 2. Literature Review Chaos and complexity dominate construction sites, imposing difficult conditions for the establishment of reliable, robust, and easily controlled schedules [7]. For the past few Sustainability 2021, 13, 11035. https://doi.org/10.3390/su131911035 https://www.mdpi.com/journal/sustainability