Application of ground penetrating radar in locating underground utilities in Taipei MRT system

The Neihu extention line of Taipei Mass Rapid Transit system is proposed to run along the main broadway of the Neihu district of Taipei metropolis in elevated structure. The 10 kilometers long route will underlain numerous public underground utilities, mainly consisted of electric cable duct, tele-communication lines, water pipes, gas pipe, sewerage culverts etc. To avoid the interference between the underground utilities and pillar foundations, a non-invasive and fast survey program for locating the underground utilities is necessary in carrying out the detailed design of individual pillar foundation before construction. Since it is impractical, both in time and economic consideration, to excavate trench for each pillar foundation site in the design stage, Ground Penetrating Radar (GPR) technique is suggested to be utilized in locating the underground utilities. GPR is proven to be a competent survey technique for locating these underground utilities. This paper describes the field operation and results of a verification survey program. From preliminary survey results and trenching data, it appears that GPR is a promising tool for such purpose.