The ultimate challenge for autonomous vehicles: cyclists
Autonomous vehicles cannot reliably identify cyclists' different shapes and inconsistent changes in speed and direction of movement. Deep3DBox, the most successful programme to detect cyclists, only spots a cyclist in 74% of cases and correctly detects the direction they're facing just 59% of the time. The unpredictable behaviour of cyclists  will make the development of a foolproof detection algorithm impossible, said Robin Hickman, a reader in transport and city planning at the Bartlett School of Planning at University College London. Instead, traffic should be moved from lower speed streets that cyclists use, said Professor David Levinson of the University of Sydney.
Picture yourself cycling down a city street in the year 2035. You’re late for a meeting, but the road you must cross ahead has recently been designated an “Autonomous Vehicle-only” route, where platoons of driverless cars whizz past, mere centimetres apart. You can’t ride across it, as cyclists and pedestrians have been banned for fear they would slow the driverless traffic. You must find a way around.

The clock is ticking. Do you attempt to climb the barrier and make a dash through the traffic? As you wait, you see a group of kids on a side street which is open to all vehicles. They are darting between driverless pods and forcing them to a stop. It’s a popular game.

Rewind to today. A report last month estimated that by 2035 up to 25% of new vehicles sold could be fully autonomous. Humans can be terrible drivers, and many proponents believe AV could reduce the 1.34 million annual global road death toll.

But cities have some urgent questions to answer and failure to address the issues raised could see us sleepwalking back into the problems of the 1960s and 70s, where cities became thoroughfares for traffic first … and places for people second.



A human behind the wheel of Hyundai’s Ionic driverless car. Photograph: Hyundai

The ‘problem’ posed by cyclists

Driverless cars navigate and detect other road users using a combination of cameras, detailed maps, radar and, in the case of Google cars, Lidar (light detection and ranging), a laser-sensing system adapted from oceanographic surveying. Google, in a company now spun off as Waymo, has been testing driverless cars (with pilots inside) on public streets in the US since 2009, clocking 2.5 million miles, and honing the technology following interactions with other road users.



A driverless car will, in theory, stop if it detects an object in its path – but cyclists, being small and agile, represent a unique challenge. AVs struggle with changes in speed and the huge variety of cycle shapes and sizes. They even struggle to detect which way a bicycle is pointing. Deep3DBox, a programme designed to identify 3D objects from 2D images, such as camera footage, is the most successful at doing this; yet it only spots a cyclist in 74% of cases, and correctly predicts the direction they are facing just 59% of the time. Poor weather makes detection even less accurate.

Former Renault-Nissan chief executive Carlos Ghosn described cyclists as “one of the biggest problems for driverless cars” last year. They confuse the vehicles, he said, because at times they behave like pedestrians, at other times like cyclists, and “they don’t respect any rules usually”.

Google has acknowledged that “it’s hard for others to anticipate their movements”. This came after one cyclist bamboozled a self-driving Lexus by performing a prolonged track stand at a junction. Google has since taught its cars to recognise cyclists’ hand signals, different sizes and shapes of bike, and allows them more space on the road.

The issue of detecting and reacting to unpredictable behaviour is far from solved, though, as the Guardian recently witnessed during a ride in a driverless Nissan Leaf. In a separate incident earlier this year a driverless Leaf was caught on camera overtaking a cyclist at very close proximity, even though the vehicle’s monitors indicated it had detected the rider.



A skateboarder rides next to an electric driverless bus in Lyon, France. Photograph: Jean-Philippe Ksiazek/AFP/Getty

‘Unworkable’

But what action should a driverless car be programmed to take when it sees a cyclist or a pedestrian in its path? And what happens if people crossing roads learn they can simply walk in front of AVs which will be forced to brake?

Robin Hickman, a reader in transport and city planning at University College London’s Bartlett School of Planning, believes this makes driverless cars “unworkable” on busy urban streets.

“In terms of the algorithm for dealing with obstacles that move in unpredictable ways, like cyclists or pedestrians, I would say that’s unsolvable,” says Hickman. “If a pedestrian knows it’s an automated vehicle, they will just take the priority. It would take you hours to drive down a street in any urban area.

“And in the context of India or China,” he adds, “where there are different types of vehicles, more pedestrians, more cyclists, I would say it’s even more difficult for the AV to mix with all these unpredictable users.”

There’s a lot of interest and people tend to get distracted by this shiny new toy Janette Sadik-Khan

The options for solving these kinds of problems are not always attractive. One possibility is an integrated network of environmental sensors, making the street an extension of the internet of things. This would reduce the likelihood, for example, that a child running out from behind a parked car could surprise an autonomous vehicle. But what about privacy?

Then there’s the idea of the electronic detection of road users via some form of RFID beacon system, which could even be built into future e-bikes. But – as Ceri Woolsgrove, road safety and technical policy officer at the European Cyclists’ Federation – says: “What about the 30, 40, 50% of pedestrians, cyclists who aren’t connected? It doesn’t exactly make you feel very safe.”

Or how about prosecuting pedestrians or cyclists who get in the way of driverless cars? David Levinson, a professor at the School of Civil Engineering at the University of Sydney, is broadly supportive of AVs, but says: “It’s very big brother like, there’s a question of safety v freedom. How much risk to endanger yourself are we going to let you take?”

Thinking back to the kids stopping driverless cars on our imaginary future street, Levinson sees a future where blocking a driverless car could even be criminalised. “The car has a camera and the picture will be sent to the police department, and the police department will come and arrest you for annoying an autonomous vehicle.”

Endless streams of traffic on Sheikh Zayed Road in Dubai. Photograph: Gavin Hellier/Alamy

Back to the 60s?

Given these challenges, experts including Hickman and Levinson believe segregation and AV-only roads are inevitable. But wouldn’t that risk a return to the urban dystopia of the 1960s and 70s, when planners crisscrossed cities with elevated highways and erected barriers around roads with the aim of improving safety? The unintended consequences were fast, aggressive driving, and the splitting in two of countless communities.

“I think there will be some roads that will be transformed to higher speed roads,” says Levinson. “I’d be sceptical of someone who says we will not do any of that. But if you can move traffic away from the lower speed streets that pedestrians and cyclists want to use, that’s an improvement.”

Hickman believes “the case is overwhelming against AVs” but fears the powerful motor industry lobby means there is so much private and government money already at stake that the rise of driverless cars would be hard to stop.

In Britain, the Department for Business, Innovation and Skills is delivering a feasibility and R&D programme worth more than £200m, via Innovate UK. This includes the GATEway programme in Greenwich, which recently turned a section of bike path along the Thames into an AV shuttle lane.

The European Commission has said it is “fully committed to a fast deployment of self-driving technologies”, citing the economic and safety benefits. A recent commission document on Smart Cities mentioned cycling only once, and that was in reference to helmets.

And in the US, legislation to allow the testing of driverless cars has been introduced in 35 of 50 states, and adopted in six. Google, Lyft, Uber, Ford and Volvo recently formed the Self Driving Coalition for Safer Streets to lobbying for more favourable federal standards.

The effect of driverless pods on healthy lifestyles, as imagined by Pixar movie Wall-E

As Hickman says: “We shouldn’t be designing our future transport strategies based on selling vehicles, we should have different objectives. It should be more about the liveability of urban life, and the benefits of active lifestyles which include walking and cycling. I think there should be a full stop after that.”

Woolsgrove of the ECF sees “potential for good and potential for evil”. “In terms of the car itself, Vision Zero could be genuinely within reach with some of these technologies,” he says. “You can programme a car to obey all of the traffic rules perfectly and to be extra vigilant of cyclists and walkers. You can literally control where the car goes.”

‘It’s about people, not cars’

Although driverless cars may be many years from our streets, some of the technology is here already. Lane departure prevention, forward emergency brakes, and automatic parking are fitted in today’s cars.

Progress is slow now, but it will reach a tipping point, after which adoption will rapidly accelerate. There is a real concern that while cities are thinking about the implications of autonomous vehicles, the ground is shifting under their feet.



The level of mapping data required for AV navigation, with accuracy down to the millimetre, means a vehicle can only currently download the information for a single city.

This makes an urban, lift-sharing scenario more likely but – as former New York transportation commissioner Janette Sadik-Khan warns – human-controlled Uber and Lyft cars have already added “tremendous” numbers of vehicles to city streets.

Sadik-Khan, who is chair of the National Association of City Transportation Officials (Nacto), says mayors around the world should be asking themselves: “What is the city that you want to be?”

“There’s a lot of interest and people tend to get distracted by this shiny new toy,” she says. “Let’s make sure that is the focus – creating the city that we want to have – and not looking at the technology as the be all and end all.

“There are some exciting possibilities with autonomous vehicles but I think we need to remember what makes a great city, and that’s really about the people, not the cars.”



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