Tex. Transportation Code § 545.405: DRIVING ON MOUNTAIN HIGHWAY.

An operator moving through a defile or canyon or on a mountain highway shall:

(1) hold the vehicle under control and as near the right-hand edge of the highway as possible; and

(2) on approaching a curve that obstructs the view of the highway for 200 feet, give warning with the horn of the motor vehicle.

Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995.