Part delivery van, part helipad—that pretty much describes a handful of Mercedes-Benz vehicles that are currently cruising the streets of Zurich. Last year we reported that drone firm Matternet and Mercedes-Benz were exploring the use of vans as rolling distribution hubs for aerial package delivery. That concept is now a reality, with a three-week trial in the Swiss city using drone-van combos to deliver goods for local e-tailer Siroop.

The experiment uses drones to shuttle parcels of up to four pounds from a distribution center to vans—at least, when they’re parked at one of four rendezvous points around the city. The vans have a special landing zone on their roof, which allows the drone to set down and drop off its payload. The driver of the vehicle is then tasked with actually delivering the package to a customer.

The idea is to help e-tailers provide on-demand delivery for customers without the need for more vehicles and drivers, or return trips to a distribution center. The approach also neatly sidesteps the issue of having customers interact with drones at their front door, which remains a thorny problem for those wanting to make drone deliveries commonplace.

Still, it remains to be seen whether hauling four-pound packages in this way is actually cost-effective, and this small-scale trial is designed to evaluate if the scheme could actually save time and money.

If it does, Matternet has big plans for the concept, with “van fleets dynamically synchronized with drone fleets for efficient on-demand delivery.” In other words, it would like the vans and drones to be in constant communication, with the vehicles not only receiving parcels at designated rendezvous points but wherever it’s safe to stop and have an aircraft land on the roof. First, though, it needs to see how this trial goes.

This isn't the only trial Matternet is running in Switzerland, either: it's also using drones to ship medical supplies between hospitals there, too.