Imagine standing on a street in need of a ride home. You enter your destination into an app on your phone, a car pulls up moments later, you get in, and the vehicle slips into the driving lane -- just as with any taxi ride.
The difference is that no one is driving this vehicle.
This may sound like science fiction. But a rapid pace of innovation in the automotive industry has turned this scenario into a possibility in the not-so-distant future.
The advent of autonomous vehicles is expected to bring a revolutionary change that will potentially save us time and fuel, prevent accidents, transform urban planning, and improve the mobility of old, disabled, or intoxicated people.
It might also help ease congestion by removing the main factor that causes traffic jams -- the multiple decisions human drivers make about speed, safe distance, and when to move or make a turn.
Larry Page, CEO of Google, one of the top firms working on self-driving, praised the values of this technology last month.
"Imagine how self-driving cars will change our lives and the landscape: more green space, fewer parking lots, greater mobility, fewer accidents, more freedom, fewer hours wasted behind the wheel of a car," he said. "The average American probably spends almost 50 minutes commuting. Imagine if you got all that time back for other things."
The revolution is already under way, with automated driver-assist systems equipping new cars.
Computerized control of a car’s steering, acceleration, and braking has been made possible thanks to lane-keeping systems, adaptive cruise control, auto-parking systems, and satellite-navigation systems.
Interaction With Other Vehicles
For a car to be fully autonomous these systems must all be tied together using software and be supplemented with a combination of sensors that includes cameras, radar, and lidar -- a laser that works like radar.
These instruments inform the software about what is going on around the vehicle, allowing it to map nearby features, spot road edges and lane markings, read signs and traffic lights, and identify pedestrians.
To become truly safe, the general view is that the car also must be able to interact with other vehicles.
According to Richard Wallace, director of transportation systems analysis at the Center for Automotive Research in Ann Arbor, Michigan, this is necessary, for example, to deal with upcoming intersections.
"If you're in a tight urban environment, radar and optical systems don't work around corners," he says. "So you have buildings and intersections blocking the view of the oncoming, 90-degree-angle lanes, and you will get intersection crashes without having radio communication also being a part of the picture."
Working prototypical autonomous vehicles have been developed, but experts expect it to be more than a decade before they are available to the public.
"Based on industry input we have, by 2018 maybe you'll have vehicles that can operate on their own, unassisted for a fairly large swath of freeway travel," says Wallace. "That is you can get into your lane, hit a button, and boom, off you go down the highway. Now, when you want to change lanes or exit you're going to go back to manual control. I would say more or less driveway to driveway, self-driving is going to be at the earliest 2025."
Google says test models of its self-driving car have gone some 700,000 kilometers under autonomous control without a reported incident.
Last month, Mercedes-Benz showed off its "virtual chauffeur" technology in its $100,000 S-Class, a car that the German firm says is capable of driving itself in city traffic and going in its own lane by itself at 200 kilometers per hour if it is running on a highway and conditions are right.
Meanwhile, Britain’s Oxford University is working on developing a self-driving car controlled by Apple's iPad.
'As Revolutionary As The Automobile Itself'
If and when autonomous vehicles do become widespread, observers say the consequences will be far-reaching for the car-insurance sector, the way we interact with vehicles, and the design of roads, cities, and cars.
Futurist Thomas Frey is the director of the DaVinci Institute in the U.S. state of Colorado. He says the driverless feature that will be added to vehicles will be "as revolutionary as the introduction of the automobile itself because it just changes virtually every aspect of the industry."
Instead of aiming to sell as many cars as possible, he predicts the industry will make its profits from charging users by the mile.
"You won't need to own your own vehicle," he says. "So, it will be like a taxi service but you’re not having to pay for the driver. Today, most of our cars are sitting in driveways, parking lots, and garages -- maybe 97 percent of the time. So we have what I call a 'just in case mentality:' we have these vehicles around just in case we need them. If cars are readily available by just pulling out your smartphone, we transition to a 'just in time mentality' so that we can have these vehicles whenever we need them, just in time for when we need them."
But experts say regular drivers will have to wait for regulations to catch up with the technology and address issues such as insurance and driver responsibility.
In the United States, where three states have legalized the use of autonomous cars, federal safety officials made their first formal policy statement on such vehicles last month.
In a nonbinding recommendation to the states, the Transportation Department advised that driverless cars should not yet be allowed except for testing, saying that the technology has not demonstrated the necessary safety capability.
Other suggestions include requiring drivers to get special licenses to operate driverless vehicles and cars to have a button within easy reach that returns control to the driver.