In connection with the acquisition of lands, property or interests therein for state highway purposes, the department may, in its discretion, acquire, by any lawful means except through the exercise of eminent domain, an entire lot, block, or tract of land or property if, by so doing, the interests of the public will be best served, even though said entire lot, block, or tract is not immediately needed for state highway purposes. Without limiting the same hereby, this may be done where uneconomic remnants of land would be left the original owner or where severance or consequential damages to a remainder make the acquisition of the entire parcel more economical to the state; Provided, that when any such property or land is left without access to a road, and the cost of acquisition of such landlocked property or land through the exercise of eminent domain would be more economical to the state than the cost of providing a means of reasonable ingress to or egress from the property or land, the state may, in its discretion, acquire such landlocked property or land thereof by eminent domain.