Assessment of the Cause and Effect of Early Damage of Cobble Stone Road Construction and Its Remedial Measurements: A Case of Nekemte Town Cheleleki Sub City

Abstract

Road constructing in Ethiopia is increasingly in demand to meet its medium and long term development programs. Most internal road of Oromia cities/town are cobblestone and gravel. Some portions along the alignment proposed and existing roads traversed low resistance of the subgrade that affect the stability of upper layers of cobblestones. Structural failures are observed on cobblestones roads, would it be constructed by good quality or low quality of materials. Nekemte Cobblestones Projects have been started in 2014 widely which were failed in most area today as we observed that needs to be addressed and a corresponding remedial measures must be drawn. A possible remedial measures had been organized for every observed failure or destroyed to obtain normal road condition of the study area. An assessment was made by using observation, interviews, laboratory and field test to determine the adequacy of the cobblestones, underlain material to serve as a subgrade for road construction based on project specifications and Ethiopian Road Authority (ERA) low volume road Specification. From the field tests and laboratory tests carried out, it is observed that the causes of cobblestone road failures of this road section are mainly due to the construction steps/sequence, quality of materials, road construction time, lack of proper design and quality control, absences of drainage structures, lack of highly compaction, lack of accurately fill fine aggregate and suddenly high loads vehicle applied on cobblestone road.