WASHINGTON - Self-driving cars are expected to usher in a new era of mobility, safety and convenience.

But here's the problem, according to researchers: People will use them too much.

Experts foresee robot cars chauffeuring children to school, dance class and baseball practice. The disabled and elderly will have new mobility. Commuters will be able to work, sleep, eat or watch movies on the way to the office.

People may stay home more because they can send cars to do things like pick up groceries ordered online.

Researchers believe the number of miles driven will skyrocket. It's less certain whether that'll mean a corresponding surge in traffic congestion, but it's a clear possibility.

Cars that can drive themselves under limited conditions are expected to be available within five years to 10 years.