FMSCA Regulation 356.9
(a) Regular-route authoritiesconstruction. All certificates that, either singly or in combination, authorize the transportation by a motor common carrier of property over:
(a)(1) A single regular route; or
(a)(2) Over two or more regular routes that can lawfully be tacked at a common service point, shall be construed as authorizing transportation between authorized service points over any available route.
(b) Service at authorized points. A common carrier departing from its authorized service routes under paragraph (a) of this section shall continue to serve points authorized to be served on or in connection with its authorized service routes.
(c) Intermediate point service. A common carrier conducting operations under paragraph (a) of this section may serve points on, and within 1 airline mile of, an alternative route it elects to use if all the following conditions are met:
(c)(1) The carrier is authorized to serve all intermediate points (without regard to nominal restrictions) on the underlying service route;
(c)(2) The alternative route involves the use of a superhighway (i.e., a limited access highway with split-level crossings);
(c)(3) The alternative superhighway route, including highways connecting the superhighway portion of the route with the carrier's authorized service route,
(c)(3)(i) Extends in the same general direction as the carrier's authorized service route and
(c)(3)(ii) Is wholly within 25 airline miles of the carrier's authorized service route; and
(c)(4) Service is provided in the same manner as, and subject to any restrictions that apply to, service over the authorized service route.
