Amazon quietly kicked off its regional Amazon Ride pilot shuttle program Monday to bring commuters from the suburbs to its Seattle campus.

The online retail giant debuted the shuttle service with little fanfare — there was no event or announcement. Instead, buses quietly began showing up on Monday morning at the company’s Brazil Building at Ninth and Republican in the South Lake Union neighborhood and at the new Doppler Building in the Denny Triangle.

Fitting with the under-the-radar pilot status of the program, and unlike the highly visible Microsoft Connector shuttles, Amazon’s buses are not decked out with company branding. The nondescript shuttles sport an all white exterior and tinted windows. The only visible logo on the bus was that of MV Transportation, which is based in Dallas and also operates the Microsoft Connector, meaning that company may be contracting with Amazon on the commuter bus project.

The buses are big, resembling charters, with what appeared to be capacity for more than 60 passengers. Most buses observed by GeekWire had at least a few people exit at the Brazil building, and some had as many as 15 or 20 people disembarking.

GeekWire first reported on the new bus service last week. Amazon released this statement, confirming the service: “Our employees tell us that they love being in the heart of the city. In fact, more than 50% of our employees get to work without a car. We are continually looking for ways to build a more sustainable urban campus and this pilot is another opportunity to do so.”

The company declined to answer our follow up questions about the popularity of the service so far and whether it will expand to more pickup locations. But the website gives a hint that more locations are on the way. So far, there are three active pickup spots in the Eastside suburbs of Bellevue, Issaquah and Redmond. Two more stops — one in Kirkland and one in Bothell — are listed on the website but do not yet have pickup or dropoff times.

At least several hundred workers will use the service to get home tonight. As of about 10 a.m. Monday morning, more than 500 people had signed up for rides. More than half — 278 people — signed up for the Issaquah route, which picks up once every 20 or 30 minutes between 4:45 p.m. and 6:45 p.m. with a final “sweeper” ride at 7:42 p.m. It has the most frequent services of the three routes, with buses to Bellevue running approximately every hour and routes to Redmond departing every 35 minutes or so. Amazon Ride’s schedule lists travel times for the three routes of about 30 to 35 minutes.

All full-time and part-time employees, as well as their dogs, are eligible for Amazon Ride, according to the site. Employees will be able to reserve seats up to two weeks in advance via an app that came online last week. For employees who need to work late or experience a sudden emergency, the service includes “Guaranteed Ride Home” coverage, up to five times per year.

Amazon Ride joins the bevy of commuting options Amazon employees use to get to work. GeekWire saw many workers trudging to the office on foot, while others waited in lines of cars to pull into parking garages. Many came in on packed King County Metro Transit buses and a few used the South Lake Union Streetcar. People took Uber and other ride-hailing services. Others arrived on scooters — both manual and electric.

Also spotted: the SLU Shuttle, which has numerous stops around the Amazon campus, ferrying employees to and from downtown and other surrounding neighborhoods. But that service does not cross Lake Washington. We even saw a few Microsoft Connector buses running through the neighborhood.

As it grew, Amazon decided to plant its flag in the middle of Seattle, rather than move out to the suburbs like fellow tech giants have. Amazon CEO Jeff Bezos has called Amazon’s decision to develop its campus inside the city, an environmentally-friendly approach and “a very attractive feature for some of our employees” who want to live in the urban core. The company’s presence here has been a major driver in the development of the South Lake Union into one of the top tech hubs in the U.S., with thousands of apartments being built there every year.

But much of the top tech talent still commutes from out of town. According to a recent Zillow study, 53.4 percent of tech employees working in South Lake Union live outside of Seattle proper. As tech giants like Amazon, Microsoft and others bring more people to the region, traffic has snarled as a result.

The commuter shuttle systems are one of several ways private and public organizations are working to unclog the region’s freeways and streets. Amazon, Microsoft, Expedia and others have donated to the campaign in favor of the Sound Transit 3 light rail expansion, which would bring 62 new miles of light rail to the region over the next 25 years.