As a result of the inconsistencies in the result of structural thickness design of flexible pavements, arising from individual differences in sight and judgment in the use of design charts and tables, a study on the development of a computer program for the design of flexible pavement was carried out. The study was based on the Nigerian (CBR) design method for flexible pavement. The thickness above layer for each pavement material was obtained by interpolation at 1% CBR interval. Using the data obtained, equations for curves A to F were developed. Using the developed equations, Algorithm and codes were written in accordance with the Nigerian (CBR) designs procedure. The results of developed program, N-Flex-Pave were validated by comparing it results with that of the conventional procedure (CBR design curve). Results show that structural thickness design using N-Flex-Pave compared favorably with the conventional procedure with a minimum ratio of 0.97 and a maximum ratio of 1.10. Calibration of N-Flex-Pave-calculated and Design Curve-measured results were compared using linear regression analysis and the results were found to be good with minimum coefficient of determination R2 of 0.996 and maximum R2 of 0.999 indicating that N-Flex-Pave is a good estimator of pavement layer thickness using the Nigerian (CBR) design procedure. Result also indicated that design can be completed in few seconds when compared to the time spent when conventional procedures are employed. A conclusion was made that N-Flex-Pave is capable of carrying out structural thickness design for the Nigerian (CBR) method and should be recommended for use by pavement engineers in Nigeria.
