Google Self-Driving Car Project CTO Chris Urmson, who has been working on autonomous vehicle technology at the company for over seven years, has announced his departure.

Urmson, a research scientist from Carnegie Mellon University, joined Google back in 2009 to help in the development of the then-secret project. He took over leadership of the initiative in 2013 after Sebastian Thrun, founder of the Google X research laboratory, left the company.

Urmson posted on Medium regarding his departure, as he looked back on the many accomplishments that the Google Self-Driving Car Project has made over the past years. He recalled that when he joined Google, the first milestone of the project was to have its modified Prius vehicles drive autonomously over distances of 100,000 miles, with those first trips not exactly going as smoothly as was hoped.

The project was able to learn significant lessons over the years, leading to the decision to manufacture the prototype vehicles of the Google Self-Driving Project. The cars, which were rolled out last year, were the first ones to be designed from scratch for self-driving purposes.

"Now, 1.8 million miles of autonomous driving later, I've decided the time is right to step down and find my next adventure," Urmson wrote, adding that he is now ready for a fresh challenge after leading Google's self-driving cars over the human equivalent of 150 years worth of driving.

"Chris has been a vital force for the project, helping the team move from a research phase to a point where this lifesaving technology will soon become a reality," wrote Alphabet spokesman Johnny Luu in an e-mail, adding that the company sends Urmson their warmest wishes as he leaves.

The X research laboratory, under which Google's Self-Driving Car Project operates, has been facing increased pressure to reveal financial returns for their efforts. While the project has been leading the development of autonomous vehicle technology, a version of the vehicle that can be sold to customers is likely still several years away.

Google hired John Krafcik, former CEO and President of Hyundai America to become the project's CEO last year. Urmson, however, has expressed unhappiness under Krafcik's leadership, and has privately quarreled with Alphabet CEO Larry Page over the direction of the project.

Urmson took a leave for the summer, and has only recently come to the decision to part ways with the project. He, however, disputed that the disagreements with Krafcik and Page were a reason for his decision to leave.

In addition to Urmson, two other executives of the project are dropping from the project, with principal software engineer and one of the project's founders Jiajun Zhu co-founding a startup along with software lead Dave Ferguson.

What is next for the Google Self-Driving Car Project after these departures?

"I have every confidence that the mission is in capable hands," Urmson wrote in his Medium post, signifying that it is business as usual for those who are still working on Google's self-driving car.

The people working on the project have chosen to focus on autonomous vehicle technology over many other possible products as they understand the impact that the vehicle could have in the everyday lives of millions of people.

Urmson promised that he will be cheering for the project and following its progress, as Google continues to work on getting the self-driving car to market.

Alphabet Executive Chairman Eric Schmidt recently claimed that the project will be ready in years, not decades, and so we will see how the Google Self-Driving Car Project unfolds.