Highway Drainage Facilities Problems (Case Study – Assessment of Drainage Problems in Adama)
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Date
2015-12
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Addis Ababa University
Abstract
Most designs of roads projects have limitations with drainage related issues. Especially,
town section drainage design and provision needs a great consideration as the scale of
damage due to lack of proper drainage facilities provision is high.
This research paper is an assessment of drainage problems in Adama, section of the
Nazareth-Assela road project, Ethiopia. Based on the site investigation, the design and the
available data of the area, the analysis has been done.
The design floods are estimated using SCS method per the requirement of Ethiopian Roads
Authority Drainage Design Manual, 2013. The spread sheet program has been developed to
estimate the design flood using SCS method. The existing structures hydraulics data have
been modeled using Hydrologic Engineering Center-River Analysis System and HY8 Culvert
analysis to determine the capacity.
The results of the finding include: a) Inadequate structure provision which the hydraulic
capacity of the crossing structures, being less than the design discharge b) Lack of properly
designed side drains c) Lack of inlet/outlet protection works of the crossing structures d)
Growth of vegetation at inlet and outlet of the crossing structures and e) Siltation and
blockage with sand and stone respectively of the crossing structures.
In this connection recommendations forwarded include: a) Due consideration, to be given to
important factors such as appropriate design method to be employed, variability of the
climate and future settlement to be taken into account during the design of the drainage
facilities b) Ensure that the drainage facilities are integrated with the master plan c) Ensure
that if the town administration takes measure to keep the serviceability of the road, the
rehabilitation needs to be supplemented by the design and d) Continuous monitoring of the
drainage facilities.
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Designs of roads projects