(a) No block shall be longer than 1,320 feet nor less than 500 feet, except in unusual circumstances. Where a subdivision adjoins a major highway, the greater dimension of the block shall front along such major highway to minimize the number of points of ingress and egress.
(b) Where blocks are over 750 feet in length a crosswalk easement not less than ten feet in width on or near the halfway point may be required if necessary to provide proper access to schools, playgrounds, shopping centers and other facilities.