The Influence of Quality Control Mechanism Implemented by Consultants on Quality Assurance of Road Projects: A Case of Dar es Salaam Metropolitan Development Projects, Tanzania

This paper aimed to examine the influence of quality control mechanisms (evaluation of work executed, supervision of work, advising on proper execution of work and inspection of work executed) implemented by consultants on quality assurance of road projects in Tanzania so as to provide a comprehensive understanding of the relationship between quality control mechanisms and quality assurance, which stakeholders can make informed decisions to improve project outcomes and enhance overall infrastructure quality. This study was guided by agency theory. The study employed a case study research design that utilized a quantitative research approach, involving 122 respondents from the population of 175 randomly selected in the 50 road projects under Dar es Salaam Metropolitan Development Project (DMDP), but valid responses were 110. The data was collected using self-administered questionnaire, and the collected data were analyzed by factor analysis and multiple regression analysis. From the analysis, the findings demonstrated that the evaluation has a negative relationship (-1.680, p < .022), implying that lower evaluation of work executed scores correspond to lower project quality. Conversely, both supervision of work (1.375, p < .001) and advising on proper execution of work (1.151, p < .026) show positive relationships with project quality, implying that higher levels of supervision and effective advising contribute to enhanced outcomes of the projects. Inspection of work executed failed to serve as a significant predictor (0.011, p >.949) which shows that its effectiveness on quality assurance did not show up as expectations compared to other mechanisms. The research reveals consultants' application of evaluation procedures and supervisory techniques together with advising practices to uphold road construction quality standards. The research finds that evaluation, supervision, and advising serve as essential quality control tools used by consultants but recognizes the need to enhance inspection practices for better process effectiveness. Consultants should prioritize rigorous supervision practices to make sure construction activities comply with specifications while adhering to safety regulations and quality standards. Adequate quality assurance requires full-time supervision through regular site visits and progress reviews combined with stakeholder coordination.