Some people have theorized that self-driving cars and ride-hailing apps will lead to the end of public transport, but really, you still can't beat the efficiency of cramming a load of people into a single bus. Combine that with autonomous driving tech and you might have a whole new sort of public transport. At least, that's what Mercedes-Benz thinks, and its semi-autonomous Future Bus program has just passed a major milestone: navigating a route of more than 20 kilometers.

Now, this is nothing compared to the million-plus kilometers traveled by Google's self-driving cars, but every journey starts with single step (or rotation of the wheel). The Future Bus followed a route from Amsterdam's Schiphol airport to the town of Haarlem, a journey that included numerous bends, tunnels, and traffic lights. Local laws meant that the bus had to have a human driver ready to take over in an emergency, but Mercedes-Benz says all its extra technology — collectively known as CityPilot — means the end ride is more safe and efficient.

The interior of the bus includes designer benches and wireless charging surfaces.

The bus's self-driving tech is adapted from software used to guide Mercedes-Benz's autonomous trucks (under the Daimler name), and is capable of recognizing all the objects on the road as well as bus stops, where it automatically comes to a halt and lets passengers on or off. Mercedes-Benz notes that even during the busiest rush hours the bus drives gently and smoothly, meaning standing passengers never have to worry about being knocked off their feet.

The bus has a top speed of 70 km/h (around 43 mph), and can communicate with a city's infrastructure network. This gives it information on when traffic lights will change (making for a more efficient journey), but it also acts a data collector for the city, using its cameras to spot wear and tear in the roads, such as pot holes, and report back to a central computer.

Mercedes-Benz points out that the number of people living of cities worldwide is growing fast, and public transport will need to improve to cope with the extra passengers. The Future Bus program is one way of dealing with this potential gridlock, and many of its key ideas (such as communicating with street lights) are also being trialled in the US.