Assessment of Pavement Distress and Remedial Measures from Addis Ababa to Gibe River Trunk Road

Abstract

The current condition of Addis Ababa- Gibe River road corridor is subjected to heavy defects. As a result of inappropriate sub base and embankment material, crack was the dominant problem from Tefki to Weliso town. In addition to this, due to a significant growth of traffic and inappropriate maintenance technique the rates of deterioration accelerated exponentially. The objective of this study was to make an assessment on pavement distress and provide remedial measures from Addis Ababa to Gibe River trunk road. In order to achieve this research objective, necessary investigations have been conducted during the study period such as road condition survey, laboratory and field test, traffic volume and traffic load analysis. Road condition survey was performed from station km 0+000 (Wolete Suk) to station km 100+000 (Weliso Town) to assess the current condition of the pavement, Failing head method was used to determine the permeability of soil sample, DCP test was conducted to determine the bearing capacity of pavement layer and axle load analysis was made based on the data acquired from BEZA Construction Engineering PLC. Except for the cracks, the severity and extent of defect was analyzed according to ERA condition survey manual of 2005 edition. Purposive sampling technique was used to analyze the permeability of soil and bearing capacity of pavement layers. Comparative approach was used to analyze the effect of axle load from 2015 to 2018 GC. The cumulative number of vehicle and ESAL from Addis Ababa to Weliso road section was significantly accelerating, which has great contribution to dislodge the pavement cracks. Accordingly, the result from road condition survey indicates that approximately 49 % of the defects have low severity and a round 67 % of the defects have high extent of deterioration. Based on the research result, the problem related to cracking is highly related to the permeability of sub base and fill material. Red cinder gravel was widely used material as sub base and fill material from Tefki to Tulu Bolo town; the permeability of red cinder soil is 2.303 x 10 -2 cm/sec which is not suitable in ponding condition. And the research finally recommend to use impermeable material as sub base and fill material in area of ponding condition during