The e-commerce giant is field testing a new machine, called Amazon Scout, for handling some packages.

The news: Amazon says it’s launching a trial of its robot, which looks like a small blue cooler on wheels, in an unspecified neighborhood in the state of Washington’s Snohomish County. The company will start with six Scouts that will make deliveries during daylight hours on some routes. The robots, which move at walking speed, will initially have human chaperones to help them avoid accidents.

The background: Amazon has been developing its own delivery infrastructure in an effort to drive down costs and reduce its reliance on delivery behemoths like UPS and FedEx. Among other initiatives, the company has encouraged entrepreneurs to launch their own local services to deliver Amazon goods, and has been experimenting with delivery drones. Street-hugging robots could be yet another way for the company to complete the “last mile” to people’s homes.

Roadblocks: There are plenty of potential ones. Unlike humans, Amazon’s robots can’t hop up steps and open gates. Nor will they be able to drop off a package if a customer isn’t present: a security code has to be entered to retrieve a package. Cities may also be wary of letting fleets of robots roam their crowded streets. San Francisco has already imposed strict limits on such experiments on its sidewalks.

Busy streets: Amazon isn’t the only company working on delivery robots. A bunch of startups, including Starship Technologies, Postmates, and Robby Technologies, are also developing them. Starship, for instance, recently began a test using its robots to deliver coffee and pizzas to students at a US university.