The sidewalks and asphalt would probably be a 15 year land improvement.  My first thought for the building is "no, it still would be 39 years", but I would need to check if there are any special rules involved in connection with that election.

For the most part, this election is for people that DON'T want the full deduction in the current year (which is rather unusual).  But you seem to want to take the full deduction, so why are you wanting to make this election?

And as I mentioned before, it is POSSIBLE it might affect the QBI calculation (I would need to check on the rules for "unadjusted Basis")