What kind of rock is best to avoid "washing out"?

Many problems can occur with little to no drainage. Due to that, a very common and serious problem is driveway washout, which can occur with various slopes, soils, and conditions. For usage at a culvert or around pipe entry or exit areas, rock that is 3" - 6" in diameter is typically used, depending on how steep the drainage area is. #2 rock would usually be the smallest rock used to prevent collapsing and to protect the driveway from erosion. Any driveway showing signs of erosion should also be repaired and resurfaced to avoid future problems.