A test method for walkability--most recently--comes from the development of the Synthetic Underlayment standard (quire recent initial publication). Negatives about slip resistance of these products were unresolved until Matt Dupuis and I volunteered to chair a TG to develop/reinvent a test method for slip resistance of steep-slope underlayments. This is important for manufacturers and contractors for rooftop safety of workers. Manufacturers will be able to list Walkability / Slip Resistance as a physical property of underlayments so users of products can compare Walkability from product to product.
The title and scope are in draft form and are under development within this ASTM Committee.