Google's Christopher Urmson, pictured, and the engineers in charge of self-driving software took journalists on a 25-minute loop through the city streets of Mountain View.

Photo credit: Reuters
GABE NELSON

Google self-driving cars master delicate dance of city driving

Gabe Nelson is a reporter for Automotive News.
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Sitting in one of Google’s self-driving vehicles feels just the same as it does with a person in control.

As I sat in the backseat of one of Google’s modified Lexus RX 450h crossovers with test drivers in the front seats, I found myself absent-mindedly and comfortably gazing out the window because it felt just like a human was in control.

On Tuesday, the technology giant pulled open the blinds to the media for the first time since Google co-founder Sergey Brin commissioned the self-driving vehicle experiment in 2009. Journalists were taken on a 25-minute loop through the city streets of Mountain View in California.

Google wanted to show that its cars can handle an urban environment with cyclists, pedestrians and tricky traffic maneuvers. The company said in April that its cars have traveled more than 700,000 miles under computer control, with a recent emphasis on surface roads, which project director Christopher Urmson described as about "100 times more difficult than freeway driving."

City driving is a delicate dance. It has hard rules, such as traffic signals and speed limits, but much of it is about drivers’ expectations -- the unwritten customs of the road: how quickly to speed up and slow down, the body language and nonverbal agreement of changing lanes.

All that must feel natural, and, at first blush, Google’s car passed the tests.

For one thing, the car knows to keep down the G-forces. It accelerates briskly from a stop, but not jarringly. It braked softly enough to be comfortable, except in one case, when we were coming down a hill and a traffic light turned yellow. The car made a snap calculation and slammed the brakes to avoid running a red light. It felt harsh, partly because of the hill, but it was probably a sensible decision.

The same goes for courtesy on the road. Google’s car knows to give other drivers and cyclists their space.

All around us, Google employees whizzed around on the multicolored bicycles that Google makes available for crossing its corporate campus. Our car approached a slow-moving bicycle on the right shoulder of the road. Rather than centering itself in a lane, as the car is normally programmed to do, it nudged over to give the cyclist a bit of extra cushion.

Then a large truck started to encroach on our lane. The car edged over again.

It showed a few other learned behaviors for safety’s sake. It waits a second or so to accelerate when a light turns green, in case a driver decides to blow through a yellow light and mistimes the maneuver. In another stab at self-preservation, Google also programmed its car to stay out of other cars’ blind spots.

Yet the Google car is not timid.

At one point, we passed a speed radar outside one of Google’s buildings. The posted speed limit was 35. As we approached, the electronic board told us we were going exactly 35. Never 34. Never 36.

I asked a test driver about that. She told me that traffic conditions permitting, Google programs its cars to move as fast as the law allows. It’s an apt metaphor for Google itself, which sees itself racing ahead of the auto industry.

You can reach Gabe Nelson at gnelson@crain.com.

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