WASHINGTON — If your dream is riding to work in a self-driving car, it’s time for a reality check. Your wait may be longer than expected, and you might have to trade speed for comfort.

Google expects to let everyday people start testing its driverless cars on public roads in as little as two years, but Sam Abuelsamid, a senior analyst for smart transportation at Navigant Research, doesn’t think that’s likely.

He says self-driving cars being tested now won’t work on snow-covered roads if their sensors can’t see the lane lines.

Then there’s this: Researchers at Imperial College London found that if self-driving cars are designed to create a smooth, train-like experience for riders, the cars will make traffic even slower than it is now.

The Atlantic CityLab reports researchers came to that conclusion after simulating what traffic at a city intersection would be like if 25 percent of cars on the road were self-driving.