Tall building & cranes etc are required to have red anti-collision lights. These are similar to the flashing red anti-collision lights fitted to aircraft.
More info on building anti-collision lights.
https://www.wetraobstructionlight.com/tall-buildings/
https://www.wetraobstructionlight.com/wp-content/uploads/2017/04/ICAO-Annex-14.pdf
The London Plane tree is pretty damn tough and can handle city pollution better than most other trees, and is resistant to disease.
It will handle most soil types and can cope with occasional floods and droughts.