As with other auto companies speeding toward autonomous driving, Mercedes-Benz is testing its products and technology in real-world scenarios, but the German company knows that autonomous driving must overcome different challenges in different parts of the world, which is why it set up a 5-continent driving test.
The 5-month Mercedes-Benz Intelligent World Drive, which ended at the 2018 Consumer Electronics Show (CES 2018) in Las Vegas at the beginning of the year, was a deep learning exercise in country-specific, real-road traffic.
An autonomous technology laden S-Class completed the around-the-world-journey dealing with challenges such as crosswalk markings on Chinese highways, right-hand turns from left-hand lanes in Melbourne, Australia, overwhelming pedestrian traffic in South Africa, and dealing with stopping school buses in North America — all of them peculiarities to their respective regions, but ones that an automated vehicle must understand and deal with in proper perspective to make intelligent driving decisions.
“The Intelligent World Drive makes it clear that autonomous driving requires global development activities and test drives,” says Ola Källenius, Daimler Management Board member responsible for Group Research and Mercedes-Benz car-development. “Automated and autonomous vehicles need international learning material from actual road traffic in order to understand traffic situations and to be prepared for different scenarios.”
Completing its education in Germany, China, Australia, South Africa and the US, in that order, the automated S-Class had to adapt to national peculiarities in infrastructure, traffic laws and regulations, and the behaviour of other road users.
For example, one of the basic requirements of automated driving is traffic sign recognition, but for speed limits alone, there are different variants — North America uses high rectangles, rather than the smaller round ones in China and Europe, and Australia uses electronic displays with variable speed limits that change according to the time of day, and can even display warning signs and messages, all within a short time span.
The “zebra crossings” in China designate pedestrian crossings in urban areas (much as what we’re accustomed to in North America), but when used on the highway, they designate the minimum observed distance between vehicles (much like our failed highway chevrons of the 1990s).
And in some North American jurisdictions, lanes are designated not just by painted dashes but sometimes by mini “domes” or reflective plates, both elevated above the road surface. They help human drivers feel or see lane designations better (especially in low-light situations) but they can confuse an autonomous lane-detection system.
Sometimes the signs and lane markings are just missing altogether, such as the missing signs at intersections in South Africa, and also warning signs at hazards such as speed bumps. Plus, overtaking on single lane roads is often performed by the vehicle being overtaken moving onto the paved should, so an autonomous vehicle would have to know when to pull over to be overtaken, or when to recognize it is being encouraged to overtake a slower-moving vehicle.
And then there is the infamous “Hook Turn” in downtown Melbourne, where a right turn (across traffic) from a road used by street cars must be performed from the farthest left lane only on a red light. The idea is to allow all forward moving traffic to pass before the turn is negotiated, and to cross the street-car tracks at right angles, presumably for safety (as it is mostly used by cyclists in other world regions). The theoretical equivalent in North America would be to turn left from the right-hand turn lane.
And then there is the interaction with non-motorized road users, such as cyclists, pedestrians and animals, all of which have their own unpredictable, and sometimes unique, road behaviours.
Ultimately, the easiest way to deal with these discrepancies is to harmonize road standards at the global level, but we’re dealing with countries where sometimes traffic lights don’t bear any authority.