Any incorporated city, in addition to powers granted by law or charter, may include in any sidewalk improvement district within the city all county roads or state highways or any part thereof which are located within the improvement district. It may cause to be built on the county roads or state highways or portions thereof within the improvement district, sidewalks for pedestrian travel, and may assess the cost thereof upon the property benefited thereby, in the manner provided by charter or law.
ORS 223.880