Via dispatch.com Auto insurer Root, which began offering auto insurance in Ohio in October, has expanded into Arizona. The Columbus-based insurer has built a model on insuring only good drivers. Drivers must apply for coverage by using Root’s smartphone app, which tracks their driving habits, such as how fast they go, how hard they brake and how hard they swerve. The app then will tell drivers whether they’re eligible for coverage. The company says its model can cut insurance rates for good drivers in half. Root says it chose Arizona because the state is embracing innovation in the auto industry, including tests for self-driving car services. The company says it is working on expanding to other states.