Runway surface friction is a critical safety concern on all airfields; however, current friction measurement equipment is expensive. Airfield managers have identified a need for contingency friction assessment tools that are cost-effective and commonly found. The current Air Force standard for pavement friction measurement is a high-speed continuous friction measuring equipment (CFME) device, the Findley Irvine GripTester. Operation of the GripTester is both labor-intensive and

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... This report details the development of an alternative, more economical measure of a surface's frictional characteristics using accelerometers. Accelerometers were standard friction assessment tools in the late 20 th century before CFMEs became standard practice. Accelerometer-based friction testers measure the peak deceleration of a vehicle during the braking motion. The vehicle's deceleration is proportional to the surface's friction coefficient. This report documents research conducted to evaluate the use of smartphone accelerometers and vehicle engine control units (ECUs) having sufficient accuracy and precision to function as decelerationbased friction assessment tools. Findings herein show that smartphone accelerometers, given sufficient experimental controls, can operate as deceleration-based friction assessment tools. This report also details unsuccessful attempts to extract usable deceleration data from vehicle ECUs and the potential future of such efforts. Regressions are presented that show correlation between smartphone deceleration measurements and highspeed GripTester measurements.