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LESSONS:

People’s Republic of China: Ningxia Roads Development Project

sector: Transport | country: China, People’s Republic of

The project completion report (PCR) identified a few important lessons from the project. There is a need for careful analysis of properties of collapsible loess at project sites since various types of collapsible loess behave differently and some treatment methods are more effective than others. (Collapsible loess is characterized by low density and cohesion, appreciable strength, and stiffness in the dry state, but is susceptible to significant deformation as a result of wetting. The approach used is applicable in project areas that are temperate and arid with annual average precipitation of about 300 millimeters. The main function of the upper layer asphalt is to provide water penetration to earthwork and skid resistance.) Also, for projects that encounter collapsible loess, sufficient budget should be allocated to the design of foundation treatment and its construction, which is more economical than having to remedy later deformed roads caused by inappropriately treated loess. Pavement layers should be constructed, to the extent possible, after 1 year or more after the settlement of earthworks, depending on the type of treatment of collapsible loess. This validation finds these lessons appropriate.

Given the significant increase in the number of affected households and the realignment of part of project construction sites, this validation would like to add a lesson on project cost estimation. Project designs need to provide adequate contingencies to cover possible changes in land acquisition and resettlement plans and unforeseen geological, topographical, and environmental aspects that could require modifications of detailed designs.

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