Tackling Tokyo in a self-driving car

Think of Tokyo and you’re likely to conjure up images of clogged multi-lane roads and 10s of thousands of pedestrians. After all, it is one of the world’s most densely populated cities, with 38 million inhabitants. While car ownership is relatively low compared to the population, around 30 million people commute on public transport every day. 

So the thought of letting a self-driving car loose on these busy streets is daunting to say the least. If it’s too assertive, it could accidentally cause carnage, and if it’s too cautious, it could simply be sat at one road crossing all day.

However, the brave and innovative engineers at Nissan have spent the last two years creating a vehicle that they say copes admirably with this city’s traffic and pedestrians. 

That’s why I found myself sitting in the back seat of a heavily modified Nissan Ariya, with executive chief engineer, Tetsuya Iijima, in the driver’s seat. He wasn’t driving, but, like here in the UK, it’s a legal requirement in Japan to have a person in the driver’s seat ready to take over the controls of an autonomous vehicle if necessary in an emergency. 

We were about to embark on a five-mile, 40-minute drive through the city. Our start and end point was the Tokyo Prince Hotel, near Shiba Park, and the car’s first hurdle was to join the dual carriageway at the front of the hotel. It did this with ease, gently gliding out onto the main road when the traffic on the main road was halted by nearby traffic lights. 

The multi-lane road wasn’t too busy, and the Ariya worked its way over to the right in preparation to take a right turn a couple of junctions ahead. Iijima explained that we weren’t going to drive through the famous Shibuya crossing, purportedly the world’s busiest crossing, which is used by up to 3000 people every two minutes at peak times, because it was actually a pretty simple, wide four-way junction, so it wasn’t that much of a challenge for the car.

Instead the car drove us under the Shimbashi overpass, through one of the city’s most complex junctions that has lots of traffic, multiple lanes, traffic lights with filters and many different road signs in Japanese and English. Again, the car positioned itself well and drove confidently through the confusing junction. 

It then weaved its way through the narrow streets of the Shimbashi shopping district, along roads clogged by parked lorries being unloaded, with large numbers of pedestrians, and buses and taxis making multiple stops, many seemingly at the last second. Progress was slow, but the Ariya navigated these obstacles in a calm yet confident manner, pressing ahead whenever it was safe to do so, but stopping whenever a pedestrian or other vehicle made it necessary. 

The rest of the route consisted of wider, less congested roads, but lots of pedestrians, who it had to stop for multiple times. It wasn’t too polite, though - if they weren’t too close to the crossing or didn’t look committed to crossing, it didn’t stop for them. 

The most surprising thing about the drive in the Ariya was how calm the whole experience felt. If I’d been driving the car through similar traffic in London, I’d have felt pretty stressed 40 minutes in, but sitting in the Ariya I felt relaxed enough to take in the scenery and chat with Iijima. 

The other pleasant surprise was the smoothness of the way the car drove itself. According to Iijima, electric cars that have no gears and responsive acceleration are better suited to autonomous driving than petrol or diesel engined models because their power delivery is instant and predictable power, and they have fewer mechanical variables and more electronically-controlled systems, such as steering and brakes, that are easier for a computer to control. 

My one criticism was that the car wasn’t always as assertive as I felt I would have been in the same driving situation. However, Iijima explained that when the system is implemented in production cars from 2027, its AI system will enable it to learn the driving style of the car’s owner, so it could be less polite at times. 

That doesn’t mean I’ll be able to get my car to drive like a ‘white van’ driver, though. The cars are likely to have three settings - similar to today’s driving modes of eco, normal and sport - and the driver will be able to select the most appropriate of these for each situation. 

How does the Nissan self-driving car work? 

The prototype Nissan Ariya-based self-driving car I was driven in is the basis for the third-generation of Nissan’s Pro-PILOT system. The result of a collaboration between Nissan and UK company Wayve, it follows on from the first ProPILOT system, which was introduced in 2016 for assisted driving on single-lane motorways, and ProPILOT 2.0, which arrived in 2019 and offered multi-lane support and hands-off functionality. 

The new vehicle is fitted with 11 cameras, five radar detectors and one LiDAR detector, and together these are known as Nissan’s Ground Truth Perception technology. They provide a constant stream of live information to the drive system about the surroundings, so it can react accordingly. 

The car relies on the data from these three systems and information from its AI Wayve AI Driver system, so unlike some other autonomous driving vehicles, including the prototype Nissan Leaf I experienced in the UK in 2025, it doesn’t need to have any map information pre-programmed into it. This means it can be used in any town or city, and doesn’t have to stick to a set route. 

Like many existing advanced driving systems, it uses images from its cameras for short-distance driving information, and LiDAR for more challenging situations, such as dark roads, or when there is poor visibility due to bad weather such as heavy rain or fog. 

The AI system provides the computation skills to comprehend and interpret the vehicle’s surroundings in real time, so it can predict what will happen next and react like a safe, skilled human driver. According to Iijima, it is so sophisticated it can learn to drive like a skilled driver in a very short time - it would take a human around four years to learn to drive to its level, but the whole project has been running for less than two years.

According to Iijima, this latest combination of technology is completely revolutionising self-driving cars. “Physical AI is a huge leap from the existing technology. It will change the world,” he enthused. 

The 2026 Elgrand MPV will be the first Nissan model to be equipped with the production version of the ProPILOT 3, when it launches in 2027, and we expect other pure electric models such as the Ariya and Leaf to gain the technology after that. 

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