Most of the roads constructed in Ethiopia fail prematurely before serving the design life duernto various causes arising from many factors. One of these roads failed before reaching designrnlife time is the Addis Ababa-Modjo Trunk Road.rnThe Addis Ababa-Modjo road is approximately 50 km trunk road and very crucial for therncountryâ€™s transportation and tourism sector as it is the main import export corridor to andrnfrom the capital, Addis Ababa. The road carries the highest daily traffic in the country. Thisrnroad was constructed and opened to traffic in the year 2000. The design pavement life wasrnestimated 15 years, however; pavement structure failure have been manifested since 2005,rnwithin the first 5 years after opening to traffic.rnFrom end of 2007 to date the Addis -Modjo trunk road is repeatedly under periodicrnmaintenance. Considerable resources have been spent during this period for periodicrnmaintenance but without solving the basic problem. This maintenance is not working as eachrnmaintained section is failing with in short period, hence, it needs finding the root causes ofrnthe failure to come up with appropriate solution.rnField and laboratory investigations which include visual condition survey, BenkelmanrnDeflection measurement, test pitting and pavement layer profiling, materials sampling andrntesting have been conducted in order to investigate causes of failure moreover, the past trafficrndata was collected and analysed. Finally based on the investigation, expansive subgrade soil,rnside drain problem, workmanship problems, use of substandard materials are found torncontribute for the pavement failure. However, it is noted that the traffic load take the highestrnshare for the cause of pavement failure. Proper treatment of expansive subgrade soil, use ofrnquality construction materials, proper maintenance design based on the forecasted traffic arernrecommended as mitigation measures.rnKey Words: Pavement Failure, Condition Survey, Traffic Loading, Maintenance, BenkelmanrnBeam, Deflection.