Hank
Officially the terms hardwood and softwood have nothing to do with the density of the wood. Deciduous trees are "hardwoods" and evergreens are "softwoods". There is a wide variation in the actual density. The "hardwoods" I mentioned are in fact quite soft, while Western Hemlock, a "softwood", is so hard when dry that you can barely get a nail in it. For this reason it was used on skid roads when horses or oxen were used for log skidding, but it rots quickly in ground contact and would not be suitable for cross ties.
Jim Grigsby
U.S. Forest Service (ret.)