For manufacturers of self-driving vehicles, the technology is relatively straightforward – radars, cameras, artificial intelligence (AI), advanced digital mapping and so on. Understanding the ‘unofficial rules of the road’ from one country to the next is the challenge.

Compare the notoriously chaotic and often fatal traffic in Ho Chi Minh City, Vietnam, to the more orderly road users of Munich, Germany – they are vastly different.

It’s said that autonomous vehicles will be everywhere in towns and cities from 2020, significantly reducing accidents by taking people out of the driving equation. Yet how can they be adapted to meet the needs of many countries with widely differing road conditions and cultures?

Bernhard Weidemann, spokesperson for autonomous driving at Mercedes-Benz, says manufacturers will eventually address this with diverse model and package options, but don’t have clear distinctions yet.

First, they are working to overcome problems identified from trials in Western countries, like how can self-driving cars replicate human interactions and be accepted on the roads?

In most countries, drivers and pedestrians use eye contact, hand gestures and other expressions to communicate intentions.

Autonomous vehicles, however, cannot recognise these signs. This became apparent during a long-distance test journey in 2013 by Mercedes-Benz in Germany with its S500 Intelligent Drive technology. As the car approached a pedestrian crossing, it stopped for an elderly lady. The woman waved the vehicle on as she wanted to cross slowly, but the system could not recognise the gesture. The safety driver had to intervene.

For the Mercedes-Benz F015 Luxury in Motion concept model, unveiled at the CES 2016 trade show, designers tried to mitigate this problem by putting blue lights on the exterior to inform other road users that the car is computer-controlled.

“A pedestrian can then pass or turn away from the crossing so the AI can continue – this is crucial to the success of self-driving vehicles, as it will help people understand and accept them,” says Weidemann.

Nissan has hired an anthropologist to help designers with such issues. The company’s IDS Concept vehicle, a vision for 2020, also uses external lights and displays to convey its awareness and intentions to people, flashing messages like ‘After You’ when giving way.

Truly autonomous vehicles will need to interact with human drivers, but again, will they have the capability?

As well as flashing indicators to communicate their intentions, people also use all sorts of physical and personal gestures. If these interactions don’t go smoothly, tensions can escalate.

“People will be unsure how to interact with autonomous vehicles,” says Chris Tennant from the Department of Psychological and Behavioural Science at London School of Economics (LSE).

Tennant and his colleagues conducted a study asking people how they feel about interacting with self-driving motors. It included 48 focus-group participants and an online survey, answered by approximately 12,000 European respondents.

He describes a scenario: an autonomous vehicle needs to overtake a parked delivery truck on a busy two-lane urban road. When there is a gap it must speedily pull out, going slightly into the other lane, and around the obstruction.

“In that situation, some people think the car will get stuck there all day because it will see an obstacle and if there is a lot of traffic, it will stop,” Tennant says. “Some commentators were clear that they would just nip right round and take advantage of the situation.”

This could be a bigger problem in some countries than others. “In Istanbul, if you don’t push into the traffic you will get rammed from behind, because they are already anticipating that is what you will do,” he says. “That doesn’t sound like an environment that autonomous vehicles can function in.”