Except as otherwise provided in subsection (b) of this section, if curbs or sidewalks at the intersection of 2 or more streets or roads are constructed or reconstructed by the State Highway Administration, by a political subdivision, or by a private contractor for dedication to a political subdivision, the curbs or sidewalks shall have ramps or curb cuts: graded onto the crosswalks of the intersection; at least 40 inches wide; and constructed to allow reasonable access to the crosswalks by physically handicapped individuals. Ramps or curb cuts are not required under this section if, for a particular intersection outside Baltimore City, the State Highway Administration determines or, for a particular intersection in Baltimore City, the Baltimore City Department of Public Works determines that: ramps or curb cuts would be contrary to public safety; the cost of ramps or curb cuts would be too great considering the need for them or their probable use; or the sparsity of population, the existence of other ways, or other factors show the lack of a need for ramps or curb cuts. Nothing in this section may be construed to prevent the State Highway Administration from certifying any project described in this section for the purpose of determining statewide eligibility for federal assistance.