Two is better than one. Mark two-way traffic with two durable aluminum signs. One sign facing each direction will notify all drivers of the change from one to two ways.
Standard: 01 Opposing traffic lane dividers shall not be placed across pedestrian crossings. 02 The Opposing Traffic Lane Divider (W6-4) sign shall be an upright, retroreflective orange-colored sign placed on a flexible support and sized at least 12 inches wide by 18 inches high.