The GDS Hydraulic Resilient Modulus Testing System (HRMTS) enables the resilient modulus and permanent deformation of unbound basesub-base pavement materials to be determined. The system, uses an axially-stiff load frame with a beam mounted hydraulic actuator to apply dynamic cyclic axial loads, with a GDS triaxial cell used to confine the test specimen. A number of options are also available for measuring axial deformations, ranging from localised LVDTs to external linear potentiometers.