Uber passengers in Pittsburgh will be able to summon rides in self-driving cars with the touch of a smartphone button in the next several weeks. The high-tech ride-hailing company said Thursday that an unspecified number of autonomous Ford Fusions with human backup drivers will pick up passengers just like normal Uber vehicles. Riders will be able to opt in if they want a self-driving car, and rides will be free to those willing to do it, spokesman Matt Kallman said. Uber, which has a self-driving research lab in Pittsburgh, has no immediate plans to deploy self-driving cars beyond the Pittsburgh experiment.