_____________________________________________________________________________________________________ *Corresponding author: E-mail: Ifynwaogazie@yahoo.com; Current Journal of Applied Science and Technology 41(39): 39-51, 2022; Article no.CJAST.93242 ISSN: 2457-1024 (Past name: British Journal of Applied Science & Technology, Past ISSN: 2231-0843, NLM ID: 101664541) Investigation of the Causes of Flexible Pavement Failure along Three Selected Roads in the Niger Delta Region of Nigeria Jonathan O. Irokwe a , Ify. L. Nwaogazie a* and Samuel Sule a a Department of Civil and Environmental Engineering, University of Port Harcourt, P.M.B. 5323, Port Harcourt, Rivers State, Nigeria. Authors’ contributions This work was carried out in collaboration among all authors. All authors read and approved the final manuscript. Article Information DOI: 10.9734/CJAST/2022/v41i393984 Open Peer Review History: This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/93242 Received 30 August 2022 Accepted 31 October 2022 Published 07 November 2022 ABSTRACT This study investigated the causes of flexible pavement failure along three major roads in the Niger delta region of Nigeria. The three selected roads are Ogbia-Nembe road, East-West Road and Port Harcourt-Aba. Different types of failure such as alligator cracks, rutting, corrugations, etc., were observed on the selected road alignments. Pavement condition and traffic surveys were carried out on the selected road locations to ascertain their causes of failure. The study method involved the use of structured questionnaires which were distributed mostly to civil engineers and other construction stakeholders. A 5-point Likert scale was used to analyze the questionnaires retrieved from the respondents. The results of data analysis of the questionnaires and traffic survey showed that lack of laboratory investigation of construction materials, poor quality of the construction materials, lack of maintenance culture, poor soil condition of the road, inadequate drainage systems and overloading of road pavements are the major factors that are responsible for flexible pavement failures of the three selected roads in the Niger delta. Keywords: Flexible pavement; condition surveys; 5-point Likert scale; questionnaires; poor soil condition. Original Research Article