Causes of failure of Nigerian roads: A review

Many cases of road failures have been reported by experts in Nigeria from North to South, East to West. Most of these roads are in a deplorable condition and professionals have attributed it to a number of causes. This study reviewed causes of failure of roads in Nigeria and categorized them into lack of careful and diligent geotechnical studies, inadequate knowledge of geology of the area, and other conditions. Roads that have failed due to lack of proper geotechnical studies include; Awotan-Akufo, Sagamu-Papalanto highway, Onitsha-Enugu Expressway and Akoko highway. Geotechnical studies provide information on the physical and mechanical properties of soil or rock around or brought to the construction site. Some roads have failed as a result of improper consideration of geology for instance the Shagamu -Benin expressway, Lagos- Ibadan expressway, Ibadan -Ife, Osogbo -Iwo expressway, Abakaliki area and Port Harcourt -Enugu expressway. Roads are founded on geologic earth materials and are greatly controlled by geology; hence, geology is very important in road construction. Other conditions such as old age, inadequate maintenance, poor design and construction, lack of drainage, use of poor and substandard materials, and heavy traffic have also led to road failures. Despite the absence of definite statistics, most experts agree that the rate of roads failure have increased in recent years in Nigeria. There is strong evidence to suggest that while geotechnical processes are becoming better controlled and more reliable, failures of small, medium and big scale geotechnical works such as roads continue to arise with embarrassing frequency in the country.