Google said Monday it has made progress on its self-driving car and was "more optimistic" about its goal of developing a vehicle that can operate "without human intervention."

In a blog post, Google said that since its last update in August 2012, "we've logged thousands of miles on the streets of our hometown of Mountain View, California" to refine the software needed for autonomous vehicles.

Google, which has been testing self-driving cars since 2010, said it has overcome some of the obstacles in urban driving.

"A mile of city driving is much more complex than a mile of freeway driving, with hundreds of different objects moving according to different rules of the road in a small area," said the post from Chris Urmson, head of Google's self-driving car project.

"We've improved our software so it can detect hundreds of distinct objects simultaneously -- pedestrians, buses, a stop sign held up by a crossing guard, or a cyclist making gestures that indicate a possible turn. A self-driving vehicle can pay attention to all of these things in a way that a human physically can't -- and it never gets tired or distracted."

Google posted a video on its blog which illustrated how the autonomous car navigates through construction zones, detects pedestrians and cyclists, and handles railroad crossings, for example.

"As it turns out, what looks chaotic and random on a city street to the human eye is actually fairly predictable to a computer," Urmson said.

"We still have lots of problems to solve, including teaching the car to drive more streets in Mountain View before we tackle another town, but thousands of situations on city streets that would have stumped us two years ago can now be navigated autonomously. Our vehicles have now logged nearly 700,000 autonomous miles, and with every passing mile we're growing more optimistic that we're heading toward an achievable goal -- a vehicle that operates fully without human intervention."