Abstract
A railway drainage system gives vital role for effective, efficient operation of rail track. This study worked on an assessment of railway drainage system problem along the Addis Ababa- Mieso railway line, specifically on Akaki rives crossing. It was done to check adequacy of hydraulic structure provided on Akaki River crossing by undertaking hydrologic and hydraulic analysis.
 Hydrologic modeling of the Akaki catchment area was developed by HEC-GeoHMS program with the help of Arc-GIS and hydrologic analysis was computed by HEC-HMS program. The catchment land use, soil type, rainfall data, Akaki river stream flow data, etc were used to develop hydrological model. SCS unit hydrograph and flood frequency analysis methods were used to estimate instantaneous peak design discharge for 50 and 100 year return period. Model input parameters were calibrated and verified with observed flow data of the river at Akaki gauging station.
 Hydraulic models were developed by HEC-RAS step-backwater to determine water-surface profiles for the bridge. Cross-sectional elevation data, hydraulic-structure geometries, roughness coefficients along with peak-discharge esti¬mated were used as input for the model.
 Finally, adequacy of the bridge was evaluated where the bridge was hydraulically efficient over its design period.
Highlights
IntroductionAbout 2000km of standard gauge railway infrastructure is under construction
Detailed hydrological assessment had been undertaken with different method such as SCS unit hydrograph with the help of calibrated and validated HEC-HMS model, and Flood frequency analysis methods Based on the HEC- RAS result, this bridge has sufficient opening size that can safely passes computed peak discharge for 50/100 years return period respectively
The minimum lower cord elevation of the bridge is 2056.33m, whereas the maximum water surface elevation at bridge location are 2053.9m and2054.08m for 50/100 year peak flow respectively i.e. greater than 2m clear space above water surface level
Summary
About 2000km of standard gauge railway infrastructure is under construction. Among this the Addis Ababa – Mieso-Dire Dawa – Dewale route is one of them. Adequate drainage system is essential in the design of railways and highway as it affects their serviceability and usable life [1]. The need to effectively remove surface water from all passengers, vehicle and rolling stock environments are essential for the network to operate safely and reliably. For the highway or railway designer, the primary focus of hydrology is the water that moves on the earth’s surface and facility that can safely convey quantity of water [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
