One aspect of global issues is roads themselves. Ive heard that any where we lay down pavement the ground beneath the road leaches a way all the neutrients in the soil. Which is fine since we dont really plan to grow anything where the roads and streets are anyways. However they say prolonged this will bleed over to create run off with extremely high mineral content that ends up in other water sources causing unhealthy algae blooms and too acidic for wildlife to utilize.
The streets themselves may also be one source of global warming. Hear me out, because I know that sounds crazy.
Trees and plants, ie grass areas absorb the suns light and dissipate heat in a balanced way. However roads heat up and radiate the heat back into the air warming the air dramatically. plants would not do this. Think of roads as heating elements like a stove top burner. They absorb massive amounts of solar radiation and super heat the surrounding air. This chemically needs to balance out. So the air in cities become warmer than they would if they were just covered by grassland or forests.
With all that said. Why not use elevated rails like the hanging rollercoaster? You can easily suspend double or quad size cars controlled by computers. Boarding stations are off the main track to allow free flow of traffic. You board and the car merges onto the main rail. Sensors prevent collisions and routes interconnect for network travel.
These cars could opperate on electric power instead of gasoline. Which eliminates dependancies on fossile fuels. You can own your own track car if you want.
Trees and plants can take back the roads and streets. There is more to this idea but I dont want it too long.