Q: I notice that some some manufacturers are offering flexible iron rather than wood or steel. What's the advantage? Are we moving toward higher wind speed standards for structural strength and is this primarily due to storms?
A: Ductile iron has a number of properties that can make it useful for many pole applications. It has the physical strength of steel with the corrosion resistance of cast iron. It weighs about 50% less than comparable wood poles and far less than concrete. It has a life span of 75 years. And it's more cost effective than steel or concrete. Of course overall cost for each project has to be considered.
Yes, we can expect the wind speed standards to be raised. For example, in some areas of California the pole design stands have been raised to 112mph from 92mph.
Paul Mauldin P.E.