Browsing by Author "DANIEL HAILEMARIAM WELDEMICHAEL"

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    QUANTIFYING AND MODELING OF SOIL DUST EMISSION RELEASED FROM GRAVEL ROAD (THE CASE OF DC4 STANDARD ROAD FROM HAWASSA REFERRAL ROUNDABOUT TO HAWASSA AIRPORT)
    (Hawassa University, 2020-08-17) DANIEL HAILEMARIAM WELDEMICHAEL
    A large portion of the Ethiopia road network is made up of gravel roads. Despite easy from locally available soil of better engineering properties, dust emission from these roads due to traffic at different season’s results in health and environmental problems. This study is aimed at quantifying and modeling dust emission from gravel roads of design class 4 design standard for the case Hawassa referral roundabout to Hawassa airport. The road segment has length of 33km divided into 3 segments (Hawassa Referral Roundabout – Loke Hospital village, Loke Hospital village – Dore Bafana Town and Dore Bafana Town – New Hawassa Airport). Based on systematic random sampling, 150 dust samples along the road at 2kms interval were collected over five months using single pocket record. Average daily traffic and mean monthly precipitation data (both for five months of 2017-2020) were collected as secondary data. Dust characterization was performed using hydrometer method of analysis. Result from the analysis indicated that 81.54% of the total sample collected was dust. Of these dust inhalable particulate constitute (%), 42.91, 38.94, 40.7, thoracic particulate (%) 21.6, 28.77, 31.26, and respirable particulate (%), 8.52, 12.95, 12.61.Labratory tests (plasticity index & shrinkage product, graduation, California bearing ratio) and field test (Dynamic cone penetration test) were conducted. The shrinkage product were 214,184,142 which all are between 100 and 250, implying dust is a major concern. Percent passing 75μm analysis indicated that segment A constitute high fine and clay content (9.65%) indicating decrease in strength. Whereas, B and C exhibit low fine content (12.66%, 10.52%) which is disposed for erosion. California bearing ratio of (32.54, 35.64 and 33.26%), indicating higher strength materials having low clay content, consequently corrugation problem exit. Multiple linear regression model was developed for the 3 segments between dependent variable (Gravel dust) and independent variables (Average daily traffic, mean monthly precipitation, plasticity index, percent passing 75μm and California bearing ratio). Negative relationship existed between gravel dust and California bearing ratio, whereas positive for remaining factors. Strong correlation was observed between plasticity index and silt content. The R2 values were 0.991, 0.939 and 0.967.To summarize, dust is a major concern on the selected segment harms human health and environment. Considering the result of this study, stake holders should give attention to dust emission before undertaking planning and maintenance activities.