Causes and effects of poor drainage system on the asphalt pavement layer: a case study in agaro to bedele road

• 24 Alignment of Drainage System – – – – – – – – – – –25 Description and Function of Road Drainage System – – – – – – – – – – – – 9 251 Description of Road Drainage Systems – – – – – – – – – – – – 9 252 Functions of Road Drainage Systems – – – – – – – – – – – – 10 26 Failures of Road Drainage System – – – – – – – – – – – – – – – – Effects27 Effects of Poor Drainage on Roads – – – – – – – – – – – – – – – – poor28 By poor drainage effects of water on road – – – – – – – – – – – – – – 11 29 Culverts – – – – – – – – – – – – – – – – – – – – – – – – 11  210 Components of a road and pavement drainage system – – – – – – – – – – 13 2101 Ditches – – – – – – – – – – – – – – – – – – – – Erosion2102 Erosion Control in Ditches – – – – – – – – – – – – – – – 14 211 Necessities to Construct Drainage System – – – – – – – – – – – – – 14 212 The Criteria for Roadside Channels – – – – – – – – – – – – – – – 15 213 Design Flood for Road Drainage System – – – – – – – – – – – – – 15 214 Flow Velocity in Road Drainage System – – – – – – – – – – – – – – 15

Chapter THREE

SYSTEM DESIGN AND IMPLEMENTATION

• – – – – – – – – – – – – – – – – – – 16 METHODOLOGY – – – – – – – – – – – – – – – – – – – 16 31 Research Methodologies – – – – – – – – – – – – – – – – – – – 16 32 Selection of the Study Area – – – – – – – – – – – – – – – – – – period33 Study period – – – – – – – – – – – – – – – – – – – – – 18 34 Research design – – – – – – – – – – – – – – – – – – – – – 18 35 Study population – – – – – – – – – – – – – – – – – – – – – 18 36 Sample size and sampling procedures – – – – – – – – – – – – – – – 18 37 Study variables – – – – – – – – – – – – – – – – – – – – – collection38 Data collection process – – – – – – – – – – – – – – – – – – – 20 39 Data processing and analysis – – – – – – – – – – – – – – – – – – 21 310 Ethical considerations – – – – – – – – – – – – – – – – – – – 21 311 Data quality assurance – – – – – – – – – – – – – – – – – – – 21 312 Limitations of the study – – – – – – – – – – – – – – – – – – – 22 313 Hydrological Analysis – – – – – – – – – – – – – – – – – – – 22 314 Hydrological Equations for Determining Peak Flood – – – – – – – – – – Method3141 Rational Method – – – – – – – – – – – – – – – – – – 23 31411 Runoff Coefficient – – – – – – – – – – – – – – – 25 31412 Rainfall Intensity – – – – – – – – – – – – – – – – 26 31413 Time of Concentration – – – – – – – – – – – – – – 26 31414 Catchment Area – – – – – – – – – – – – – – – – 27 3142 The SCS method – – – – – – – – – – – – – – – – – – 28 31421 Catchment Area – – – – – – – – – – – – – – Rainfall-Runoff31422 Rainfall-Runoff Equation – – – – – – – – – – – – – – 28 31423 Time of Concentration – – – – – – – – – – – – – – Curve31424 Runoff and Curve Numbers – – – – – – – – – – – – – 32 31425 Hydrological Soil Groups – – – – – – – – – – – – – 34 315 Investigations of Design and Construction Practices on the study area – – – – – 34 3151 Design and Construction Practice at Station 18+160 – – – – – – – – 35 3152 Design and Construction Practice at Station 24+200 – – – – – – – – 36 3153 Design and Construction Practice at Station 42+120 – – – – – – – – 37

Chapter FOUR

SYSTEM TESTING AND EVALUATION

• – – – – – – – – – – – – – – – – – – – 39 RESULT AND DISCUSSION – – – – – – – – – – – – – – – 39 41 Results from questionnaires analysis – – – – – – – – – – – – – – – – 39 411 Causes and effects of poor drainage system on asphalt road that response from the Engineers – – – – – – – – – – – – – – – – – – – – 39 4111 Causes of poor drainage on the flexible pavement road – – – – –4112 The effects of poor drainage system on the road – – – – – – – 40 4113 Appropriateness of the drainage system – – – – – – – – – 42 4114 State of the drainage services – – – – – – – – – – – –412 Causes and effects of poor drainage system on asphalt road that response from road users – – – – – – – – – – – – – – – – – – – – – 43 4121 Level of road users‟ satisfaction of the drainage system – – – – – 44 413 Causes and effects of poor drainage system on asphalt road that response from the residents – – – – – – – – – – – – – – – – – – – – 45 42 Results from observation and photography – – – – – – – – – – – – – – 46 421 Causes and effects of poor drainage system on asphalt road Surface due to poor drainage that collected from the field with the photography – – – – – – – 47 43 Results from Hydrological Analysis – – – – – – – – – – – – – – – Watershed431 Descriptions of Watershed Area – – – – – – – – – – – – – – 51 432 Computation of Catchment Parameters – – – – – – – – – – – 52 4321 Catchment Parameters at Station 18+160 Drainage system – – – – 5at4322 Catchment Parameters at Station 24+200 Drainage System – – – – 58 4323 Catchment Parameters for Design and Check at Station 42+120 – – – 58 44 Peak Discharge Computation – – – – – – – – – – – – – – – – – –   59 441 Peak Discharge at Station 18+160 Drainage System – – – – – – – –   59

Chapter FIVE

SUMMARY, CONCLUSION AND RECOMMENDATIONS

• – – – – – – – – – – – – – – – – – – – 62 CONCLUSION AND RECOMMENDATION – – – – – – – – – – 62 51 Conclusion – – – – – – – – – – – – – – – – – – – – – – – 62 52 Recommendation – – – – – – – – – – – – – – – – – – – – – 63 REFERENCES – – – – – – – – – – – – – – – – – – – – – – 64 APPENDEX – – – – – – – – – – – – – – – – – – – – – – – 67 APPENDIX A: Time of Flow, Unit Peak Discharge, Velocity of flow and SCS CN Charts 67 APPENDEX B: Roughness and Runoff Coefficient Values and Parameters for the Design of Drainage Structures – – – – – – – – – – – – – – – – – – – – – – 74 APPENDIX C: Questionnaire Type – – – – – – – – – – – – – – – – 82