Aurora self-driving technology powers the big-rig, but there’s still a safety driver. That truck driving down the interstate might not have a flesh-and-blood driver.

On Wednesday FedEx announced its first autonomously-driven Class 8 truck delivery route (“Class 8 truck” is an industry term for what many Americans call a “semi-trailer truck”). Working with truck maker PACCAR and self-driving company Aurora, which is backed by Amazon, FedEx will start making deliveries in Texas using an autonomous semi.

The route on Interstate 45 between Houston and Dallas is about 500 miles round trip, and expected to be busy as the holiday shopping season approaches. The test route will run multiple times each week starting Wednesday. The Aurora-modified trucks will drive in real, everyday traffic, and a safety driver will be behind the wheel, but the trucks will be operating in autonomous mode.

Inside the truck cab, Aurora’s autonomous equipment includes a screen showing what the truck is seeing around it from the cameras, LiDAR, radar, and other sensors stacked onto the big-rig. Aurora has been developing Level 4 self-driving trucks with other partners like Volvo. At that level of autonomy, the truck can handle itself without human intervention in most situations and driving conditions.

FedEx has dabbled in other high-tech delivery methods, like with Nuro’s delivery bots. That project was focused on the so-called “last mile” to get packages to doorsteps. But the Aurora trucks mark a first. Until now, FedEx hasn’t let self-driving computers take over on the highway for hundreds of miles.