Abstract:
The structural behavior of pavements can be affected by seasonal variation in
environmental factors such as temperature and moisture content. In Ethiopia the design,
construction and maintenance process of roads mostly give attention to structural
thickness of pavement layers, on which the designers and authoring focus on expected
future traffic. However it is critical to admit in practical the variation of pavement
material properties due to seasonal environmental changes, especially the temperature
and moisture. This study focused on assessment of the impacts of environmental
factors(temperature and moisture) on performance of flexible pavement in generally and
particularly on Tarcha - Omo River highway, hence doing this study, the objectives were:
to investigate the impact of temperature on the performance of selected highway, analyze
the impact of moisture on the performance of pavement through laboratory based
investigation and to examine the efficiency of the drainage system in removing excess
water from the pavement structure of selected highway by collecting all primary data
from the project site and secondary from, standard specification, Ethiopian roads
authority, Omo River-Tarcha road upgrading project. An assessment was done by using
both field observation and laboratory tests to characterize materials toward the factors.
The field observation was made to investigate the condition of drainage system in
removing water from pavement and surrounding. The sample of base course, sub base
and sub grade were collected from three different sampling stations and laboratory tests
were conducted and finally compared with standards to check the moisture sensitivity of
materials. NMC, Compaction, Particle size distribution, CBR and Atterberg’s Limit were
tests conducted. Statistical Microsoft Excel 2007 software was employed to analyze the
data. The assessment showed that temperature and moisture has considerable impact on
performance of flexible pavement and the pavement failed due to moisture variation on
pavement base, sub base and subgrade, due to, inadequate drainage facility, lack of
effective protection work and excessive water in the sub grade in first section and
temperature in second section of study. Therefore Standard of construction and design
should be improved. More research should be carried out on the engineering geo techniques of study road
