This seems less like a "visionary concept" and more like a "well, duh" concept, but looking at Google Maps I was noticing how many places adjacent to the LRT could be planter strips that aren't. For instance:
It would seemingly help the heat island if these area's were filled with planter strips and trees. Additionally it would of course beautify the city and as the tree's grow and vault and create that ceiling feeling it would give our streets more of a sense of place.
Here in Boston they do a good job of this, many of their Light Rail lines have trees on either side of them:
The train line is back behind the diagonal parking and the line of trees.
Obviously we'd never get that kind of tree density in a desert but it would be nice to at least have some palms, cacti, agaves, lantana and some tall/thin trees (that wouldn't interfere with the trains) like Jacarandas in those areas where planter strips are.