Seven-and-a-half years ago I joined what was then a secret project within Google. For decades, self-driving cars have been dreamt of in science fiction. The question was could we make that dream a reality?

My own journey with self-driving cars had begun a few years earlier with the DARPA grand challenges, where my team at Carnegie Mellon competed to navigate a vehicle autonomously across the desert and later through a 60-mile mock city. Driving an average of 14mph, with no pedestrians and relatively well-behaved traffic, my team from Carnegie Mellon came out on top. Compared to the thousands of miles Google’s self-driving fleet now travel on real roads each day, this may seem like a drop in the ocean; but even then, we saw this as a step towards creating something that could improve road safety, save lives and transform mobility.

When I arrived at Google, our first milestone was to have our modified Prius cars self-drive 100,000 miles including “interesting” roads such as the twisty highway from Santa Cruz to San Luis Obispo. Like the miles of a teenager on their first drive, our first trips in 2009 were not exactly smooth. But it taught us many lessons that our cars still heed to to this day (pro tip: it’s always a good idea to slow down before a turn!).

One hundred thousand miles soon became five hundred thousand — and soon our cars were capable enough to have people outside our team try them during their freeway commutes. From that experience, we learned some valuable lessons about human nature, and made the decision to develop a self-driving car that could shoulder the entire burden of driving and help anyone get anywhere they wanted to go.

So we turned our attention to teaching our car to navigate city streets, including the extra challenges of detecting cyclists and pedestrians. In 2015, we rolled out our prototype vehicles — the world’s first car to be designed from the ground up to be self-driving.

Now, 1.8 million miles of autonomous driving later, I’ve decided the time is right to step down and find my next adventure. Today will be my last day on the project as CTO. After leading our cars through the human equivalent of 150 years of driving and helping our project make the leap from pure research to developing a product that we hope someday anyone will be able to use, I am ready for a fresh challenge.

It has been a tremendous privilege and honor to be part of a team that has been at the forefront of bringing this life-saving technology to the world. I feel lucky to have played a role in building this team from a handful of people into the world-class team it is today, readying self-driving cars that will soon take you from A to B at the push of a button. If I can find another project that turns into an obsession and becomes something more, I will consider myself twice lucky.

I have every confidence that the mission is in capable hands. There are many other problems or products this talented group of people could work on, but they’ve chosen self-driving cars because they understand the impact their work can have on making our roads safer and bringing everyday destinations within reach for millions of people. I will be cheering along and following their progress.