(a) Generally sidewalks shall be required on both sides of the street in all residential subdivisions where the predominant lot width is less than 100 feet and may be required in other instances by the Planning Commission. No sidewalks will normally be required where the predominant lot width is greater than 150 feet.
(b) Public sidewalks shall be required for all commercial lots.
(c) Public sidewalks may be required for industrial lots, subject to the approval of the Commission.
(d) Curb walks of three-foot width may be granted as a variance to conventional four-foot sidewalks.