Road construction equipment (machinery type vehicles) operating laden or unladen within the limits of a project are not required to display the $5 machinery license plate, regardless of the intermingling of regular vehicular traffic; however, conventional commercial vehicles operating within the limits of a project shall be required to be registered with regular commercial plates whenever traffic is allowed to intermingle. A highway construction project is that section of the highway between the warning signs giving notice of a construction area.
43 Tex. Admin. Code § 217.50