Over the past year, Amazon has been on a drone and transportation patent spree as the online retail giant continues to make moves toward becoming its own delivery service.

In mid-December, Amazon CEO Jeff Bezos shared a video of a successful fulfillment of an Amazon order delivered via drone. In August, Amazon unveiled its own airplanes. The year before, the company purchased a fleet of trucks.

Since launching its two-day and same-day delivery services, Amazon’s shipping costs have skyrocketed. According to the company’s last quarterly report, which ended in September, its shipping expenses are up 43 percent from the same time the year before; Amazon spent $3.9 billion on shipping in its last reported quarter.

Here are some flying-, driving- and tunneling-related patents Amazon has been awarded in the past year alone.

Floating warehouses

Amazon won a patent for its design of floating fulfillment centers for its drones to collect packages to deliver to people on the ground below. The airborne warehouses would float some 45,000 feet in the air and be recharged and restocked using smaller aircraft that shuttle to the dirigible. The patent was awarded in December 2016.

Highway networks for self-driving trucks

Earlier this month, the company was awarded a patent for a network to communicate with self-driving vehicles about changes in traffic patterns, like when a highway uses reversible lanes that can be relabeled to go in either direction or when vehicles cross state lines with new traffic laws and restrictions.

A voice-controlled drone that can fit in your pocket

The company designed a personal voice-controlled drone — imagine an Echo with a propeller. In its October 2016 filing, Amazon suggested the drone could be used to replace dashboard-mounted cameras in police cars or be used to help find lost cars in parking lots. The drone is pictured as small enough to perch on a police officer’s shoulder.

A drone that can land on a truck

Amazon won a patent in September for a system that would allow drones to land on and hitch a ride on a truck. The idea is twofold: The drone can save energy by riding on the truck for as far as it makes sense to do so, and to provide the aircraft a safe place to land in case its power gets low or it malfunctions.

A network of tunnels to deliver packages underground

In one of the company’s more ambitious patents, Amazon proposed a subterranean tunnel system to deliver orders through conveyor belts, rail or pneumatic tubes that would be able to bypass congestion on roadways. The underground delivery tunnels could connect airports to fullfillment centers, or even route directly to someone’s house. The patent was awarded in November of last year.

Aerial drone recharging stations on street lights

Amazon filed a patent for drone docking stations where an aircraft can safely land to get help if the weather conditions are too rough or if a drone needs to recharge its battery or receive new directions. The patent, awarded July 2016, envisions these docking stations could be built on existing electrical or phone poles or street lights.

Drones that can assemble to carry large packages

For packages that are too big for a single quadcopter drone to carry, Amazon patented a collective unmanned aircraft configuration that describes how multiple drones can assemble, link together and share the load. Awarded at the end of last year, the patent explains how drones can connect to share battery power or operating instructions, or even fly collectively to a common point before breaking apart to make individual deliveries.

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