On May 11, 6:02*pm, mm wrote:

With a rail fence, three rails will each bear as much load as the two
rails would,

Each? Not quite - each rail in a three rail fence will only have to
take 2/3 of the load on a rail in a two rail fence.

and the load on the posts will be 50% higher.

The only difference is the weight of the rail and the additional
fasteners. Not sure where you get the load difference numbers.

R