You’ll probably hail an autonomous taxi long before you’ll have the opportunity to buy your own self-driving car.

Alan Hall, who handles technology, research, and innovation communications for Ford, expects that the first application of the technology will be in automated taxis in certain cities.

The idea would be similar to the way ride-sharing services work now. You’d summon your ride with a smartphone, and it would send a car to your location, then deliver you to your destination. Except, no driver.

That is, provided your destination was within the city. Hall says that early implementations of self-driving cars would work only “in a defined area that is mapped, in appropriate weather, in a city environment.”

Experts agree that it will be a very long time before autonomous vehicles will have free rein over every road in America. Before that happens, every road, highway, byway, bridge, and obstacle needs to be mapped. And we’re not just talking the ordinary maps currently in your car’s navigation system. According to Google’s Chris Urmson, autonomous cars need detailed 3D maps that capture all features of the road, including lane markers and traffic signs.

Weather is also a big concern. Snow covers up the lane lines that cars’ cameras use to find their way. To counteract that, Ford has been testing cars at Mcity, a 32-acre simulated urban driving environment at the University of Michigan. The cars use high-resolution 3D maps, which provide information about road markings, signs, geography, landmarks, and topography. The goal is that when the Ford can’t see the actual road, it will still be able to detect above-ground landmarks to orient itself on the map.

A self-driving car’s software has to be ready for even the most bizarre circumstances and be ready to temporarily violate traffic laws—say, if a police officer or traffic worker waves the car into oncoming traffic lanes to avoid an obstacle. Could a car know to stop at a green traffic signal to avoid hitting a person chasing their dog into the street? Imagine the billions of lines of software code needed to accomplish that.

Editor's Note: This article also appeared in the May 2016 issue of Consumer Reports magazine.

From the 'Consumer 101' TV Show

Modern cars can do many things, including helping to steer, keeping you in your lane, and stopping in an emergency—just don’t call them “self-driving” cars in front of this CR expert.