''Urban renewal project'', a project to be undertaken in accordance with an urban renewal plan (1) for acquisition by an urban renewal agency of the land and all improvements thereon, if any, within a decadent, substandard or blighted open area covered by an urban renewal plan and for assembly or clearance by such agency of the land so acquired; or a project (2) for the elimination and for the prevention of the development or spread of a substandard, decadent or blighted open area covered by an urban renewal plan by means of rehabilitation or conservation work, which work may include the promulgation and enforcement of building and other codes within such area or the restoration and renewal of any such area or portion thereof, including the preservation, restoration or relocation of historical buildings, by carrying out plans for a program of voluntary repair and rehabilitation of buildings or other improvements or by the acquisition by gift, purchase or eminent domain of land and all improvements thereon, if any, and demolition, removal, or rehabilitation of any such improvements whenever necessary to eliminate unhealthful, unsanitary or unsafe conditions, lessen density, mitigate or eliminate traffic congestion, reduce traffic hazards, eliminate obsolete or other uses detrimental to the public welfare, provide land for needed public facilities or otherwise remove or prevent the spread of blight and deterioration; or a project (3) involving any combination of the foregoing types of project. ''Urban renewal project'' may also include the provision of financial and other assistance in the relocation of persons and organizations displaced as a result of carrying out a project, the installation, construction or reconstruction of public and private ways, public utilities