COMPARATIVE STUDY OF DB AND DBB DELIVERED ASPHALT CONCRETE ROAD CONSTRUCTION PROJECTS: A CASE OF ETHIOPIAN ROADS AUTHORITY

Abstract

Achievements are measured by whether or not the projects are completed on time, budget and specified quality. Now-a-days, it has become difficult to complete projects on time, budget and specified quality. Design Build and Design Bid Build are the widely used project delivery systems. Ethiopian Roads Authority is widely using ancient delivery system Design Bid Build and alternative delivery system Design Build. Most of the projects in Ethiopia are delivered using design bid build delivery system. Therefore, this research tried to analyze the challenges on asphalt concrete road construction projects delivered in design bid build and design build in Ethiopian Roads Authority to see whether one is more effective than the other one with regards of cost overrun, time delay, and quality performance. The research targeted on identifying the main challenges of asphalt concrete road construction Projects and then based on the identified main challenges, identifying challenges for main challenges and comparing their impacts on both Design Bid Build and Design Build delivered projects for identified main challenges. With this regard, the objective of this paper is a comparative study of Design Build and Design Bid Build delivered asphalt concrete road construction projects in Ethiopian Roads Authority. Extensive review of literature is conducted and challenges on asphalt concrete road construction projects were explored that can influence to complete on time, budget and specified quality. Desk study, questionnaires and case study survey are applied and data gathered from forty seven respondents using non-probability sampling technique from the targeted population of the clients, contractors, consultants and professionals. Data collected by likert scale method and analyzed using quantitative analysis; interpreted using Statistical Package for Social Sciences software version 26 and discussions are made on the results. Results in case of desk study for cost overrun and time delay in design bib build and design build are 76.92% and 38.46%, and 38.46% and 23.68% respectively. The mean value results on identifying main challenges of the delivered projects of time delay, quality performance, cost overrun, selection of delivery system, risk mitigation and external environment are 4.55-very high, 3.51-high, 3.04-medium, 2.60-low, 2.19-low, and 2.15-low respectively. In case of questionnaire analysis mean values of cost overrun, time delay and quality performance for design bid build and design build are 3.26 and 3.04, 3.61 and 3.46, and 3.67 and 3.37 respectively and in case of case study mean value results are 3.56 and 3.19, 2.95 and 3.03, and 4.07 and 3.68 respectively. The Research result discovered that, from the main challenges of asphalt concrete road construction projects time delay, quality performance and cost overrun respectively are ranking very high, high and medium. Therefore, they were taken as the main challenges and after identifying these main challenges again, questionnaires were distributed to identify which challenges are more triggering time delay, quality performance and cost overrun on construction sites in both deliveries. The results of the comparative evaluation of the identified challenges for three main challenges shows that design build has less time delay, better quality performance and fewer cost overruns than the Design bid build. Therefore, based on the result of the research the client and stakeholders of asphalt concrete road construction projects should use design bid delivery method for the upcoming projects and should focus on research-based solution on the identified challenges, which are still triggering time delay, quality performance and cost overrun.