Spectra performed a ground penetrating radar pilot study along sections of FDR Drive in Manhattan. The purpose of this survey was to investigate a section of FDR Drive to evaluate subsurface conditions including pavement structure and to identify potential voids beneath the pavement.
Spectra performed the investigation in the north bound lanes of FDR Drive in the lanes closest to the median, near East 40th Street. A portion of the investigation area contained a steel plate that was believed to cover an area where voids may exist beneath the pavement.
Spectra’s technicians used a 1600 MHz antenna, with penetration depths of about 1-2 feet, and a 400 MHz antenna, with penetration depths of about 5-6 feet.
The study revealed that there were variations in the pavement structure in the areas of investigation. Metal reinforcement was present beneath the majority of the site; however, some areas lacked reinforcement and appeared to be missing some pavement layers. The survey also identified two areas where pavement appeared to be subsided and subsoil layers beneath it were deformed.