Berhanu, Girma(PhD)Alebachew, Fiker2018-06-182023-11-112018-06-182023-11-112005-04http://etd.aau.edu.et/handle/12345678/1301Paved roads in tropical and sub tropical climates often deteriorate in different ways to those in temperate regions, because of the harsh climatic conditions, lack of proper design and quality control, high loads and inadequate assessment for identifying causes of distresses before carrying out maintenance and rehabilitation. A pavement distress that occurs at the surface can have a number of different causes which must be properly identified before corrective action is taken. The visible manifestation of the problem at the surface may be the same; however, the solution for each cause may be different. Therefore, if the remedial action is to be effective, the cause of the problem must be identified and corrected. The present road condition of Addis Ababa shows rapid deterioration. The severity of pavement distresses is even more critical on the major arterial roads were the traffic volume of busses, heavy trucks, passenger vehicles and taxies is comparatively 61 higher than other road network. Such severe distresses summed up with inadequate road signs and markings are resulting congestion and consequently causing further deterioration of roads due to maximum static load sustained from the vehicular traffic waiting in a queue on the pavement. This research mainly focuses on making assessment of asphalt pavement condition, identifying causes of pavement distress and proposing maintenance options for the arterial roads of Addis Ababa. These roads are most widely utilized, and therefore prone to severe distress and consequently exhibiting repeated maintenance and repair. Visual distress assessment, roughness tests, DCP tests and other necessary laboratory investigations were carried out on selected test sections in order to have better understanding of the pavement response and come up with identification of probable causes. Major causes of pavement distress associated with load, drainage and durability are tried to be identified. A statistical analysis is also made to check how each investigation results showing pavement response variables and material properties interact with each other to identify the cause of distresses. The visual survey analysis indicates that almost all test roads have very low PCI value. Raveling, corrugation, Bumps and sags are the most dominant type of distresses constituting more than 75% of the distress densities in the arterial road network. The majority of test sections showing low PCI values are observed to have a base material of low bearing value sandwiched between the asphalt and other pavement layers. The investigation and analysis also showed that moisture and drainage associated distresses are predominant in the arterial roads and most likely on the whole network as well. Moreover, it is also observed that most of the existing pavements lack structural adequacy and hence require reconstruction than doing a routine maintenance and/or rehabilitation.enRoads; Causes ; MaintenanceThesis