Ask HN: Alternatives to Sidewalks?

Hello. I live in a midsized city in the US that, for the most part, lacks sidewalks. As a results, the walkability of the city is poor. The reflexive response is, “just build more sidewalks”. But this can be expensive and I would think might interfere with utilities (ie water to residences, sewage line from residence, etc). Does anyone know of examples or alternative schemes for making streets more walkable that have actually been put into place?