Abstract: Moveable barrier apparatus is disclosed for use in controlling traffic along parallel lanes of a roadway. The apparatus includes elongate channels which are embedded in the roadway transversely of the lanes at spaced-apart positions. Carrier cars are mounted by roller bearings for movement lengthwise within each channel, and posts which are mounted on the cars extend upwardly above the roadway through slots formed along the channels. An elongate upstanding barrier is mounted on the posts to form a divider between adjacent lanes of the roadway. Actuators are mounted in each of the channels for moving the cars and posts lengthwise of the channels for selectively changing the transverse position of the barrier. In one embodiment the actuator comprises a single hydraulic ram, and in another embodiment the actuator comprises a pair of telescoping hydraulic rams positioned on opposite sides of the car within the channel.