It is pretty frustrating when the development community in the boomtown (aka 'it' town) that is Nashville complains about contributing to the neighborhoods that they are richly profiting from. They should do the right thing and put in their piece of sidewalk infrastructure.
What I can say, is that it never gets cheaper. Sidewalks are expensive but the easiest time to put them in is during construction - the equipment is there and the land already torn up.
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In addition, sidewalks add value as they improve quality of life. They increase the value of homes.