When the distance between the rear of the semitrailer and the front of the following trailer is 10 feet or more, the dolly shall be equipped with a device, or the trailers shall be connected along the sides with suitable material, which shall indicate to other Turnpike System users that the trailers are connected and are in effect one unit. These devices or connections shall be approved by the Commission prior to use on a tandem trailer combination.
67 Pa. Code § 601.107