The other day I rode in a car that no one was driving.

Well, OK, there was a guy named Mike in the driver’s seat. But he wasn’t touching the steering wheel or pedals. That was left to a system connected to a 2.7 GHz Intel Quad-core blade server—and essentially three backup systems—stacked in the cargo area of the Ford Explorer in which I rode. Riding along were Randy Iwasaki, chief deputy director of California Department of Transportation (Caltrans) and Chairman of the Intelligent Transportation Society of America, and Federal Highway Administrator Thomas Madison, Jr.

The self-driving Explorer, outfitted by the Southwest Research Institute (SRI), pulled onto 11th Avenue in New York City, drove two blocks south, made a U-turn in front of a parked van, weaved through barricades, stopped at a stoplight, crept past a parked van, looking for pedestrians that might step out in front of it, made another U-turn three blocks later, turned right, and parked itself in front of the Jacob K. Javits Convention Center.

Mostly it worked flawlessly. If you count driving like an overly cautious, newly minted teenage driver as flawless. At least, we didn’t hit anything, never errantly crossed a lane line, and Mike was never forced to take over.

Two radar units were fitted on the front bumper, and the SUV kept track of its position via GPS satellites. The radar could identify objects beside the car and in front, informing the computer to enable safe lane changes. SRI says it has had the machine up to 80 mph under autonomous control, and it expects that is about the limit of its technology. One caveat is that GPS mapping data is not precise enough: programmers have to tell the machine exact coordinates of things like lane dividers and curbs.

Along with the second-place-winning Stanford University entry from the Defense Advanced Research Projects Agency (DARPA) Urban Challenge that was on hand, this Explorer showed it is possible for cars to drive themselves, even in a challenging urban environment. I have no doubt that the day will come when cars can drive themselves in many situations. But the jerky ride up and down 11th Ave. (especially when it came to the brakes) showed there’s a lot more development work needed before computers can substitute for human vision and judgment. For now, the technology is promising, though like a teenager, supervision is recommended.

—Eric Evarts