A sidewalk constructed or reconstructed after April 12, 1973 on public or private property for public use within this state, whether constructed by a public agency or a person, firm, corporation, nonprofit corporation, or organization, shall be constructed in a manner that will facilitate use by persons with physical disabilities. At points of intersection between pedestrian and motorized lines of travel, and at other points when necessary to avoid abrupt changes in grade, a sidewalk shall slope gradually to street level so as to provide an uninterrupted line of travel. The state transportation department shall prescribe standards of slope gradient, width, and slip-resistant qualities that will assure that a sidewalk accommodates a person in a wheelchair or other persons with physical disabilities. All agencies of state and local government including school districts and other groups aforementioned, public or private, shall comply with these standards and this act when undertaking construction or reconstruction of affected streets, curbs, or sidewalks, except that a local unit of government may adopt ordinances that provide for standards at least equal to those provided by the state transportation department.