Those things are not opposed to each other. In fact one benefits from the other. One is national, the other is more local. And the main thing holding back citi

Those things are not opposed to each other. In fact one benefits from the other. One is national, the other is more local. And the main thing holding back cities is cars and removing them is not primarily a cost issue, but a political one. As for what will it solve, it decarbonize the most important air routes in your country. It will serve as a backbone for the transportation network of your country for next 100 years.