INVESTIGATION INTO ASCERTAIN THE CAUSES OF FAILURE AND PRESENT TRAFFIC CAPACITY OF HIGHWAYS
ABSTRACT
The essence of this project work is to look into the causes of highway failure and the different types of failure which are presented along the Eliozu – New Airport road in Obio/Akpor L.G.A in River state, taken as a case study. Some factors identify as being responsible for the failure of the chosen road section includes, poor sub grade soil with questionable material. Ground water study is carried out, which give insight to it effect to the failure of the flexible pavement, lack of drainage facilities, improper pavement design, poor compaction and traffic volume increase and lack of maintenance are critically taken into consideration.
Traffic volume count and soil test analysis and test on asphalt such as extraction-gradation test, are properly carryout, of which it result gives an adequate insight to the various causes of the failure situation experience along the road section through this investigation, show that relative to pavement, base course, wearing course and sub base were to less than the requirement for effective functionality of the said road of case study.investigation into ascertain the causes of failure and present traffic capacity of highways From the investigation carryout, useful recommendation are made to improve the design and proper ways of reducing the rate of failure in Nigerian highways.
INTRODUCTION
In construction of highway, generally the roads are not designed to last forever. It is been designed to serve some purpose for a specific time. As it can be seen in engineering work, the life span of a road is always an important factor that must be taken into consideration as one of the criteria for the construction. This really depends on the factors like construction procedure and consideration, the soil water relationship, quality of workmanship during the construction and the type of maintenance culture adopted.
Many roads (Highway mostly) are seen widely as attaining the state of failure and show signs of distress before the expected life span used for construction is reach, due to the lack of factors such as lack of maintenance culture etc. many of our road today serve as death trap and hang out for hoodlums going by the number of accident recorded daily on them as a result of bad paved road.
Pavement failure can be defined as the failure of the constructed layer of durable material of specified thickness, usually of concrete, asphalt or bituminous materials assigned to carry wheeled vehicles. Due to the number of load passing through a pavement structure, some deflection of the surface and underlying layers occur. The deflection can be as a result of the excess load, poor material usage, and poor road foundation resulting from the nature of the soil or groundwater rise in the area of high groundwater level. If layers are lacking in strength, repeated applications causes roughening and cracking that ultimately lead to failure of the pavement structure.
