This project developed a field instrument for automated rapid permeability measurements of pavement base or subbase. The instrument has the advantage of being highly portable and avoids the need for large volumes of water. Following development and testing of the new prototype Permeability Test (APT) device and a new sensor verification/calibration panel, design drawings, specifications, and system configurations for the final version of the device were developed. Further development and improvements were also done on the housing unit, programmable digital display panel, interchangeable orifice for precision flow control, ruggedized wheel cart/pick-up system for rapid testing, a serial port computer connection for data logging, and a cable extension with push-button data logging. The digital display was programmed to output gas flow rate, which is a calculated value from the inlet and chamber head pressures. A form fitting polyurethane base plate seal was designed and leak tested successfully.  A large compaction mold permeameter, 1000 mm in diameter and 300 mm high, was developed for verification testing with the APT device. Comparison permeability measurements demonstrated that the APT was within one order of magnitude of laboratory and another in-situ permeameter test device that use water. Work in the final phase focused on field testing of the developed permeameter. Measurements at test sites on US 63 in Iowa, I-94 in Michigan, and US 22 in Pennsylvania indicated strong correlations between APT measurements and fines content. The contractor's final report is available.