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 – – – – – – – – – – – – – – – – Effects

27 Effects of Poor Drainage on Roads – – – – – – – – – – – – – – – – poor

28 By poor drainage effects of water on road  – – – – – – – – – – – – – – 11 

29  Culverts – – – – – – – – – – – – – – – – – – – – – – – – 11  

210 Components of a road and pavement drainage system  – – – – – – – – – – 13 

2101 Ditches  – – – – – – – – – – – – – – – – – – – – Erosion

2102 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:  – – – – – – – – – – – – – – – – – – 16 METHODOLOGY – – – – – – – – – – – – – – – – – – – 16 31 Research Methodologies – – – – – – – – – – – – – – – – – – – 16 

32 Selection of the Study Area  – – – – – – – – – – – – – – – – – – period

33 Study period – – – – – – – – – – – – – – – – – – – – – 18 

34 Research design  – – – – – – – – – – – – – – – – – – – – – 18 

35 Study population – – – – – – – – – – – – – – – – – – – – – 18 

36 Sample size and sampling procedures  – – – – – – – – – – – – – – – 18 

37 Study variables  – – – – – – – – – – – – – – – – – – – – – collection

38 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 – – – – – – – – – – Method

3141 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-Runoff

31422 Rainfall-Runoff Equation – – – – – – – – – – – – – – 28 

31423 Time of Concentration  – – – – – – – – – – – – – – Curve

31424 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  – – – – – – – – – – – – – – – – – – – 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 – – – – – – – – – – – – – – – Watershed

431 Descriptions of Watershed Area – – – – – – – – – – – – – – 51 

432 Computation of Catchment Parameters – – – – – – – – – – – 52 4321 Catchment Parameters at Station 18+160 Drainage system – – – – 5at

4322 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 – – – – – – – – – – – – – – – – – – – 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