For any development or enlargement on Block 3 with a building wall facing 45th Road, a sidewalk widening of five feet shall be provided on 45th Road between 23rd Street and Jackson Avenue. Such sidewalk widening shall be a continuous, paved open area along the front lot line of the zoning lot at the same elevation as the adjoining sidewalk and directly accessible to the public at all times. Such sidewalk widening shall be unobstructed from its lowest level to the sky except for temporary elements of weather protection, such as awnings or canopies, provided that the total area (measured on the plan) of such elements does not exceed 20 percent of the sidewalk widening area, and that such elements and any attachments thereto are at least eight feet above curb level, and that any post or other support for such element, or any attachment to the support, has a maximum horizontal dimension of six inches. No street trees, vehicle storage, parking or trash storage is permitted on such sidewalk widening.