A joint study from the American Automobile Association (AAA) and Harvard has revealed how uncomfortable many drivers are about sharing the roads with self-driving vehicles.

The study, conducted with the Technology and Public Purpose Project at Harvard Kennedy School’s Belfer Center for Science and International Affairs, revealed that 53 percent of drivers surveyed felt less safe sharing the road with self-driving semi-trucks while 47 percent felt less safe sharing roads with other self-driving vehicles.

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In the study, the AAA noted that 38 states and the District of Columbia have active self-driving test pilot projects in operation. While many of these programs, particularly those in California and Nevada, are well-publicized, many others aren’t. In fact, just 35 percent of those that responded to the survey knew that some states allowed self-driving test vehicles on public roads. Additionally, 34 percent of those surveyed said they are in favor of self-driving pilot programs while 36 percent said they oppose them. The remaining 31 percent said they were unsure about such programs.

Of those that opposed the programs, 77 percent said they had concerns over the safety of sharing the road with self-driving vehicles while 62 percent had concerns over who would be responsible for crashes with self-driving vehicles. More than half also believe that the public needs to know the best way to behave around autonomous test vehicles.

The study also revealed that some of the anxieties of drivers could be overcome if autonomous test vehicles were easier to identify. In fact, 62 percent said they would feel safer if such vehicles were clearly marked. Meanwhile, 60 percent said they want dedicated lanes for self-driving vehicles. In the study, the AAA said regulators should establish guidelines that make such vehicles more identifiable.