they are planter boxes too which should protect the trees from salt buildup.
100% correct. The additional buffer provided by the bike lane (much less spray than a car travel lane, further helps).
I'd like to see a cross-section of these planters. It would be lame if they were just concrete boxes, and didn't have subterranean silva cells or something to support larger tree growth.
I would certainly hope so, of course, the City with its re-do of the Application Information portal has deleted all the supporting documents such as the landscape plan that would contain that.
I could certainly hope that the sidewalks are floated over Silva Cells or other similar tech allowing for long-term root growth.
Superficially though, this looks like very good soil volume and proper tree placement. (they aren't right at the ends of the planters, allowing more balanced root growth. )