In order to improve the air quality in southern Maine, trucks, including truck tractors but excluding pickup trucks, all as defined in 29-A M.R.S.A. §101, may only operate in the two farthest right hand lanes on any section of the Turnpike south of Mile Marker 44 that consists of three lanes in each direction.
99-420 C.M.R. ch. 1, § 1A