Some city government officials and advocacy groups say they are uneasy about aspects of self-driving vehicle legislation that is taking shape in the U.S. Senate.

They’re worried the legislation could undercut the ability of cities to enforce local traffic laws. They also want to ensure that states and localities have ample access to self-driving vehicle data, which might be used to identify safety risks and to manage roadways.

There are other questions as well. Like how any final bill might deal with driverless buses.