SAN FRANCISCO (Reuters) -Alphabet's Waymo robotaxis have driven more than 100 million miles without a human behind the wheel, doubling the mileage in about six months, a top company official said, as it speeds up deployment in U.S. cities amid rising competition.

Waymo's push comes as Tesla expands its self-driving taxi service after a small trial with about a dozen of its Model Y SUVs in a limited area of Austin, Texas last month.

While Tesla CEO Elon Musk has said Tesla will scale up the service rapidly and launch in several U.S. cities by the end of 2025, Waymo with about 1,500 vehicles has been expanding its service cautiously for years. It is currently available in San Francisco and some other Bay Area cities, Los Angeles, Phoenix, Austin and Atlanta.

"Reaching 100 million fully autonomous miles represents years of methodical progress now accelerating into rapid, responsible scaling," said Waymo's chief product officer, Saswat Panigrahi.

"As we expand to serve more riders in more cities, we'll encounter new challenges that will continue strengthening our service," Panigrahi added.

Waymo had logged about 71 million autonomous miles as of March, up from 50 million miles at the end of 2024 and 25 million miles through July 2024. It had completed its first million miles in January 2023.

Commercializing autonomous vehicles has been harder than anticipated with high costs, tight regulations and federal investigations forcing many, including General Motors' ( GM ) Cruise, to shut down. Among the few still in the race are Amazon's Zoox, which is testing a vehicle without manual controls such as a steering wheel and pedals, and plans to launch the commercial services in Las Vegas this year.

Until Tesla's robotaxi roll out last month, Waymo was the only U.S. firm to operate uncrewed taxis with paying passengers.

Waymo, Tesla and Zoox and others have faced federal investigations and recalls following collisions.

Despite multiple traffic problems and driving mistakes as Tesla tiptoed into the robotaxi business after years of missed promises, Musk expanded the service area in Austin and said last week it will roll out services in the San Francisco Bay Area within two months.

Waymo in March said it aims to launch fully autonomous ride-hailing in Washington, D.C. next year. It has applied for a permit to operate autonomous vehicles in New York, with a trained specialist behind the wheel in Manhattan, and said last month it will start by manually driving in the city until it gets the permit.

Robotaxis from Waymo, which started as Google's small self-driving project in 2009 and spun out seven years later, now cover more than two million miles per week autonomously.

As of May, the company has completed more than 10 million autonomous trips, up from 5 million trips at the end of 2024.