Road Failure in Nigeria has been a monumental disaster that has resulted to loss of lives and damage of vehicles which has also in turn increased the travel time of motorist plying on the these roads. In order to unravel the cause of this disaster geotechnical, geochemical, mineralogical and geophysical tests were conducted to evaluate the cause of failure along Sagamu-Papalanto Highway southwestern Nigeria. The laboratory tests result conducted shows that the percentage amount of fines ranges from 12-61.3%,natural moisture content ranges from 6.8 to 19.7%, the liquid limit in the range of 25.1-52.2%, linear shrinkage between 3.96 to 12.71%, plastic limit ranges from 18.2-35%, the plasticity index ranges from 5.2 to 24.6%,free swell in the range from 5.17 – 43.9%,maximum dry density from1.51 -1.74g /cm 3 , the specific gravity ranges from 2.52-2.64 and the CBR between 3-12%. The Cone Penetrometer Test (CPT) has a resistance value in the range of 20-138 kgf/cm 2 .There is the predominance of kaolinite as the major clay minerals and the main oxides in the study area shows SiO 2 , Al 2 O 3 , Fe 2 O 3 , K 2 O,Na 2 O, MgO and CaO.2D Electrical Resistivity Wenner Array Method was employed in the investigation. Four profiles covering a distance of 250 meters for profiles 1, 2, and 3 and 500meters for profile 4 each were established parallel and perpendicular to the road pavement along the sections of the road. Data were gather along the four profiles using ABEM Terra meter SAS 1000. The recorded field data were filtered and inverted using 2-D modelling inversion algorithm with the aid RES2DINV Software . The results revealed a low resistivity values for profile 2 and 3 ranging from 100 Ωm – 300 Ωm, between distances of 20 m – 240 m along the profile to a depth of 7.60 m and a low resistivity value ranging from 50 Ωm – 111Ωm, between distances of 80 m –120 m along the profile to a depth of 15m from the surface of the profile the topsoil along the profile. The low resistivity values and low shear strength obtained from the profiles shows the study areas comprises of incompetent materials which has the propensity to retain water and eventually results to swelling and collapse under imposed load with subsequent failure as the resultant effect. Sections of the road with sandy and clayey materials should be scooped out from the subsurface to a depth of 3 m – 5 m from the top soil of the road and put back with competent fill materials.