[caption id="attachment_86818" align="alignnone" width="500"] Uber is now offering the option of hired-car services to residents in Sonoma County, after expanding to Marin and Napa counties. (image courtesy of Uber)[/caption]

SANTA ROSA and SONOMA -- San Francisco-based Uber Technologies has continued its expansion in the North Bay, following the launch of its mobile phone application-centered transportation service in the cities of Santa Rosa and Sonoma on Monday.

The startup, which contracts with freelance drivers dispatched via a mobile application, expanded into Marin County in January and Napa in April. The move further into the North Bay comes after those successful launches, particularly in Marin County, spokesman Spencer Rinkus said.

"Marin and Napa absolutely pushed us to expand into Santa Rosa and Sonoma," Mr. Rinkus said. "We've seen steady growth in both of those cities each week, and we measure that by watching how many requests are coming in, and if new users are starting to ride with more consistency."

Napa has about 20 drivers signed up, and Sonoma County expects to have a similar range, he said. But including Marin, where many residents were already familiar with the service because they work in San Francisco, "there are hundreds of drivers in the North Bay."

"Of all the places that Uber rides can be requested in the North Bay, Marin has significantly more drivers than Napa, Santa Rosa or Sonoma," Mr. Rinkus said. "Napa is growing rapidly, and we expect that Santa Rosa will take off at a similar rate. As demand goes there, we'll make sure there are drivers to pick up those requests."

Uber (uber.com) and other ride-sharing companies have proliferated over the past few years, harnessing mobile technology to disrupt the traditional taxi industry in cities large and small. Uber, started in 2010, is now in more than 100 cities worldwide and has continued to grow at a significant clip.

But it has also drawn the ire of both the taxi industry and regulatory agencies across a number of states, including California, for differing levels of insurance premiums and disagreement on whether the ride-sharing companies or the independently contracted drivers should be held liable in the event of accident.

In recent months, Insurance Commissioner Dave Jones proposed that ride-sharing companies, now dubbed "Transportation Network Companies," carry a minimum $1 million commercial liability insurance policy that begins the moment a driver switches on the mobile application as well as a $1 million policy addressing underinsured and uninsured drivers.

Elsewhere on the state level, the California Assembly Insurance Committee approved legislation addressing the matter and sent AB 2293 to the full Assembly for a vote. The bill, sponsored by Susan Bonilla, D-Concord, would require such companies to disclose to drivers upfront that their personal insurance may not apply while operating as a TNC vehicle, define that TNC activities begin once the app is turned on and end when it is turned off, clarify that TNC’s liability insurance is the primary coverage and require TNC’s liability insurance to defend and indemnify drivers when a claim or accident occurs.  

In the past the company has said its policy already provides $1 million in commercial liability and $1 million in underinsured and uninsured drivers, and that its policy leads the emerging TNC industry.

Mr. Rinkus said he couldn’t offer specifics on evolving regulations.

"I know that as a company we want to follow rules and comply with whatever is required of us," he said.

Numerous other ride-sharing companies such as Lyft and Sidecar, both based in San Francisco, have been cited in the insurance-coverage concerns as well.

Nevertheless, Uber said it will continue to grow into whatever region offers enough demand. As in Napa and Marin, Santa Rosa and Sonoma riders will be able to use increasingly appointed levels of service, called UberX, UberBlack and UberSUV.

"You should be able to request a ride in every area of the North Bay, and having people adopt the app so quickly in Marin and Napa made it clear that Uber is something people want," Mr. Rinkus said.

First-time riders in Sonoma County are receiving $20 off their first ride.