Ground Stiffness Surveys LLC (GSS) is a specialist testing developer, researcher and contractor in Advanced Continuous Surface Wave (ACSW) technology, the first integrated surface wave system specifically designed for rapid and robust construction engineering testing. GSS's ACSW system is an innovative, sustainable and low-risk solution to obtaining high quality ground profiles cost-effectively and non-intrusively. ACSW testing measures the speed at which surface waves generated by a vibrating source travel through the ground. ACSW provides representative ground stiffness and shear wave velocity profiles (Vs) for accurate in-situ design stiffnesses, site characterisation, seismic design & liquefaction assessment. The system is rugged, highly reliable and capable of working in the extremes of the construction environment including sub-zero temperatures. Each tests takes only around 30 minutes to complete, with rates of 20 test or more per shift shift readily achievable Uniquely the company designs and manufactures the ACSW testing system, based around its cutting-edge integrated data acquisition and analysis software, C-DAS. C-DAS controls tests, allows on-site viewing of test results and subsequently completes advanced inversions of data to give a layered stiffness or Vs profile. Our website has extensive resources on the specification and use of ACSW data. GSS also publishes regularly in technical journals to encourage the practical engineering application of ACSW.