Comparative study of design-bid-build and design-build-maintain contracts delivery methods for highway projects in Rwanda

Abstract

This thesis examines the performance of two contract delivery methods—Design-Bid-Build (DBB) and Design-Build-Maintain (DBM) within Rwanda’s highway construction sector. The research places special emphasis on the DBM model when applied using Output and PerformanceBased Road Contracts (OPRC). Given the persistent issues of cost overruns, schedule delays, and inadequate long-term performance in Rwanda’s road projects, the study seeks to understand how contract delivery methods influence these outcomes. A mixed-methods approach was used, including surveys, interviews with professionals from government agencies and consulting firms, and case studies of completed highway projects. The research focuses on six key performance indicators: cost control, time management, construction quality, lifecycle performance, maintenance outcomes, and stakeholder satisfaction. Findings consistently show that the DBM approach, especially when combined with OPRC, outperforms the traditional DBB method across all indicators. DBM projects demonstrated more predictable costs, faster completion timelines, superior construction quality, and improved maintenance performance. This is attributed to the DBM model’s integrated structure, where the contractor is responsible for design, construction, and long-term maintenance,encouraging accountability and efficient resource management. In contrast, DBB projects showed higher vulnerability to cost overruns, design changes, and fragmented responsibilities, resulting in diminished performance and stakeholder dissatisfaction. The study also found that DBM projects, through their built-in performance monitoring and aligned incentives, foster higher stakeholder confidence and satisfaction. Although DBM may involve more complex planning and procurement, it provides better long-term value through reduced lifecycle costs. The thesis concludes that for Rwanda’s infrastructure goals, centered on efficiency, sustainability, and cost-effectiveness the DBM approach, especially when implemented through OPRC, is more suitable and should be prioritized in future highway projects.