The Hydraulic Performance of 900mm Diameter Pipe Culvert Using Wenchi - Sampa Road as Case Study

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
Inadequate drainage of surface and subsurface water can have significant impact on road pavement behaviour and long-term maintenance costs. Interception of water before it infiltrates into the pavement foundation is essential unless the soils are truly free draining. Most pipe culverts are not seen by the travelling public and become noticeable only when a problem arises, such as flooding or settlement in the roadway. Occasionally there is an accident because an unexpected hydraulic failure of pipe culvert causes flood to overtop the roadway. In the past, the 450mm, 600mm, 1200mm and 1800mm diameter pipe culverts were used as cross drainage structures. Due to the hydraulic inefficiencies of the 450mm and 600mm diameter pipe culverts, the Ghana Highway Authority and the Department of Urban Roads decided in the 1980s to make the 900mm diameter pipe culvert (or its equivalent box culvdrt) the minimum cross drainage structure for their roads, as a regulatory measure. However, the hydraulic inefficiencies associated with the 450mm and 600mm diameter pipes were still found with the 900mm diameter pipes. This therefore necessitated the study into its hydraulic performance using the reconstructed 30km section of the Wenchi - Sampa Road in the Brong Ahafo Region of Ghana, as case study. Forty- five 900mm diameter concrete pipe culverts were covered in the study. The prevailing conditions at their locations were assessed. Generally, about half the number of the 900mm diameter pipe culverts were silted and few had their inlets and outlets scoured. The Regional Office of the Ghana Highway Authority was surveyed by administering a questionnaire to find from them their inspection and maintenance programmes for the 900mm diameter pipe culverts on the project road. Much of the information presented has been taken from the Field Survey Results. Information  from the literature has also been incorporated and adapted where necessary, to fit highway needs. Appropriate recommendations were made based on the findings.
A Thesis submitted to the Department of Civil Engineering, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science Road and Transport Engineering.