Figure 5(b) Maximum Forward Reach over an Obstruction. The maximum depth of an obstruction with knee space below is 25 inches (635 mm). When the obstruction is less than 20 inches (510 mm) deep, the maximum high forward reach is 48 inches (1220 mm). When the depth of the obstruction is greater than 20 inches (510 mm) and less than 25 inches (635 mm), the maximum high forward reach is 44 inches (1120 mm). A clear floor space 48 inches (1220 mm) long and 30 inches (760 mm) wide is provided.