Subsurface Investigation on Federal Route Failure at Pengkalan Raja, Pontian, Johor

Abstract Road settlement is one of the major problems that often occurs in soft soil ground areas. The combination of destructive test method (trial pit, Standard Penetration Test (SPT) and borehole) and non-destructive method by using seismic refraction, electrical resistivity tomography (ERT) and ground penetrating radar (GPR) were performed to identify the factor causing the tension cracks and road differential settlement. The study area selected is at Section 39 to 50, Federal Route (FT005) Johor Bahru to Malacca (Pengkalan Raja, Pontian, Johor) because of the severe road condition which may cause an accident to road user. This paper presenting the result of destructive and a non-destructive test. From results of borehole, seismic, and ERT, the road was underlaid by 7-12m of a soft compressible layer. The GPR image showed the existing of concrete slab below the road has deviated from its original position and may not function as a foundation of road. In conclusion, the combination of destructive and non-destructive method is best approach in identifying the underground failure because it is the fastest solution, economical and suitable in area of high volume of traffic.