Texas Transportation Code - TRANSP § 644.002. Conflicts of Law

(a) A federal motor carrier safety regulation prevails over a conflicting provision of this title applicable to a commercial vehicle operated in interstate commerce. A rule adopted by the director under this chapter prevails over a conflicting provision of a federal motor carrier safety regulation applicable to a commercial vehicle operated in intrastate commerce.

(b) A safety rule adopted under this chapter prevails over a conflicting rule adopted by a local government, authority, or state agency or officer, other than a conflicting rule adopted by the Railroad Commission of Texas under Chapter 113, Natural Resources Code.