Parking space as required in the foregoing shall be on the same lot with the main building, except that in the case of buildings other than dwellings, spaces may be located as far away as 600 feet. Every parcel of land hereafter used as a public parking area shall be surfaced with gravel, stone, asphalt or concrete. It shall have appropriate guardrails, parking blocks, etc., where needed as determined by the Administrator. Any lights used to illuminate said parking areas shall be so arranged as to reflect the light away from adjoining premises if in a residential district and/or from adjoining streets.