Bridge Replacement for Improved Rural Access Sector Project

Considering the construction costs and number of subprojects as tentative when there are significant technical unknowns that cannot be determined during the design stage will help mitigate the risks and facilitate the implementation of sector loan projects. Under this project’s preparatory technical assistance (TA), cost estimates were prepared under conditions of significant technical information gaps for all potential bridge sites. The TA used past bridge construction contracts to establish cost estimates, an imperfect method that lacked specific details due to the limited sample of relevant projects. The lack of detailed construction drawings for the selected bridges made it difficult to develop tentative bills of quantities. The depth of rock layers, which could only be gauged by geotechnical surveys during the final design and engineering phase, and the unknown number of replaced bridges that could be reinstalled elsewhere, all contributed to the tentative character of the TA cost estimates. Overall, this meant that the construction costs and the number of subprojects can only be finalized after the completion of the detailed engineering design. The project followed this approach, which provided a more realistic implementation plan and timeframe that better reflected the borrower's institutional settings and approval procedures and the executing agency's (EA) project management capacity. The approach also facilitated implementation and provided an adequate level of risk mitigation, specifically in terms of preventing potential cost overruns.