Though wood may be pressure treated, it is still not waterproof, or UV proof, and a right of way constructed from it will gradually suffer from slow deterioration. I was working with a buddy on an indoor flooring project (my kitchen) and in the back of his pick up cab was a product I had never even heard of before. He described it as a liquid bed-liner for decks (i.e., PT wood - they also make a version for concrete). The stuff is water based and goes on REALLY thick. Don’t know how it would work for layouts already down, but it might make sense for new construction. The FAQ’s on the website indicate that it may not stick too well to new wood - it’s optimized to adhere to old, weatherbeaten wood - but a once over with a pressure washer might do the trick.
http://www.synta.com/prod_restoredeck2.html
Brian
Taxachusetts