WASHINGTON—Ride-sharing company Uber Technologies plans to begin reminding passengers to wear seat belts by pinging driver phones and sending riders messages amid a spike in U.S. traffic deaths. Uber told Reuters its new feature that launches Tuesday aims to alert riders to buckle up via a distinctive chime from the driver’s phone and a simultaneous push notification to the rider’s phone. “The intent is really just to help remind riders that they should be buckling up—every seat, every time,” said Kristin Smith, Uber’s head of Global Road Safety Policy, who added the chime “sounds kind of like an airplane seat belt reminder.” Uber wants riders to get in the habit of always buckling up. It plans to send riders to push notifications at the start of their next five trips and then periodically thereafter. Last week, the National Highway Traffic Safety (NHTSA) estimated that U.S. traffic deaths climbed 12 percent …