This is discounting all of the other positives mentioned in my post which will probably make this $4B investment an investment which pays off in droves in reduc

This is discounting all of the other positives mentioned in my post which will probably make this $4B investment an investment which pays off in droves in reduced material use by the nation on cars and repairs, in reduced health care spending for respiratory illnesses, in reduced spending on funerals, reduced dependence on oil, and potentially even side effects such as reduced psychiatric visits (green spaces have very positive benefits, and if reclaimed parking and lane space is used effectively, it could make our cities much more healthy places to live).