Most U.S. drivers have concerns about sharing the road with self-driving vehicles, according to a new survey.

With on-road pilot programs and testing of self-driving vehicles increasing, the AAA teamed up with the Technology and Public Purpose Project at Harvard Kennedy School’s Belfer Center for Science and International Affairs to find out motorists’ thoughts.

The survey found that most drivers have concerns, with the vehicle type and driving scenario making little to no difference in easing that apprehension.

Despite concerns, the survey also found that implementing certain measures would ease driver anxiety. Sixty-two percent of motorists asked for clear markings to show that the vehicle is self-driving, 60 percent called for designated lanes and 31 percent wanted restrictions for self-driving vehicles on times of day and/or days of the week.

Currently, 38 states and the District of Columbia have active programs that allow self-driving test vehicles to operate on public roads.

The AAA says that, as state programs continue to grow, it is critical for policymakers and other state government officials to take actions that will build confidence and foster public acceptance of self-driving vehicles.