Browsing by Author "Solomon, Habtamu"

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    Chemical Stabilization of Expansive Sub-grade Soil Performance Evaluation on Selected Road Section in Northeastern Addis Ababa
    (Addis Ababa Universty, 2011-03) Solomon, Habtamu; Kumar, Tarun (PhD)
    Expansive soils are characterized by volume change due to variation in moisture content. The cyclic wetting and drying processes causes vertical movements in expansive soils and these movements lead to failure of pavements. These soils have very low load bearing capacity too when wet. These problematic expansive soils, therefore, when encountered as sub-grade should be avoided or treated properly. The removal of expansive soils and replacement with suitable fill material is an appropriate method in areas like Addis Ababa in most cases where there is suitable fill material available nearby. At places, however, its feasibility depends on the availability of suitable fill material within economic distances and the thickness of the poor sub-grade soil to be replaced. Chemical stabilization is another alternative being applied worldwide even if the method is at a conceiving stage in Ethiopia. In recent years there are tendencies to use lime and other chemicals to stabilize sub-grade and sub base materials by Ethiopian Road Authority (ERA) and Addis Ababa City Roads Authority (AACRA). In the present study, hence, the performance of a locally manufactured hydrated lime and an imported industry product Anyway Natural Soil Stabilizer (ANSS) were evaluated based on laboratory test results on expansive sub-grade soils collected from Gerji area. The sub-grade soil was first characterized based on Atterberg limits, linear shrinkage, CBR and percent swell of CBR. The test results showed that the sub-grade soil is classified as A-7-5 in the AASHTO and MH in USCS systems. These soils have very low load bearing capacity and are highly expansive nevertheless of the mineralogy of the sub-grade soil samples have no montimorillonite, as expected in such soils. Two soil layers on colour variations were observed in the field: the upper dark gray clay soil and the lower light gray clay soil. The effects of the chemicals were then evaluated on two soil samples. The improvement of the sub-grade soil samples increased with increasing both dosages as well as curing periods. In general terms, increasing the dosage has more significant effect than that of increasing the curing period and 4% of either chemical has resulted in adequate improvements of the subgrade soil. In most cases the performance of hydrated lime is better than that of ANSS and the improvement of the dark gray clay soil is better than the light gray clay soil.
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    Fleet Management Practice and its Implication for Fleet Performance in Ethiopian Pharmaceutical Supply Agency
    (Addis Abeba University, 2021-09) Solomon, Habtamu; Temesgen, Busha (Ph.D.); Kleineidam, Julia(M.Sc.)
    Fleet management is a component of transportation management that gives due concerns to the work of vehicles in the supply chain management pipeline. The general objective of this study is to assess the fleet management practice, its implication for fleet performance, and associated challenges of the Ethiopian pharmaceutical supply agency. Institution based descriptive and explanatory cross-sectional study designs were employed in this study. Sampling was done purposively both for the agency’s branch selection and study participant selection. Data collection and analysis was accomplished with mixed quantitative & qualitative research approaches, and document review. The relationship and predictability between the dependent and independent variables were determined with Spearman correlation and ordinal logistic regression analysis methods. Qualitative data were analyzed using thematic analysis technique. The descriptive findings reveal that vehicle routing & tracking (Mean=3.59) is the most practiced fleet activity. The correlation and regression analysis show that maintenance & repair (ρ=0.559, p=.000), fuel (ρ=0.458, p=.000), and routing & tracking management (ρ=0.421, p=.000) have a significant association and predictive power for the fleet performance of the agency. The qualitative findings shows that delay of vehicle maintenance & repair due to the absence of spares was the major challenge for the agency. Though there is significant and positive association between all fleet practices and fleet performance, driver management do not significantly predict fleet performance of the agency. The researcher recommends that EPSA higher officials need to build well-organized workshop and give more concern for fuel, tracking and maintenance activities.