MUNICH — Brake, start, drive, brake again. Above all, be careful not to drive into the car in front of you. Stop-and-go traffic is annoying and unproductive. But soon cars will drive by themselves. And that raises all kinds of new possibilities, like reading the newspaper, checking your emails, or having breakfast — all while respecting the road laws.

Not bad, right? This, apparently, is the future for passengers of self-driving cars. It all sounds very practical. And if you believe what car manufacturers are saying, it's not going to be much longer before this becomes a reality. But will self-driving cars really be as hands-free as all that?

The truth is, we're still going to need to wait awhile until the passenger can really give the wheel its full autonomy. Because first of all, people and cars have to learn to coordinate with each other.

What customers can buy today are known as "Level 2" systems. The driver must constantly monitor the traffic and the assistance systems. Taking your hands off the steering wheel or quickly typing a message? Not allowed.

But even in the next stage of development — with Level 3 systems — vehicles still won't be autonomous from start to finish, though they will replace the driver in certain situations. Another problem is that international regulations haven't yet caught up to the quickly developing technology, as Audi, which announced a move toward Level 3 systems in 2017, can attest.

Testing the technology

Then there's the problem of coordination. If cars can control certain situations safely, but not all, they need to let the driver know when he or she must return to the wheel. Machine and man need to be in sync, in other words, and that's more complicated than it seems.

Because of legal requirements, it's unclear how long these issues will take to be sorted out. The German federal government, with its 36.3 million-euro research project "Co-Haf" involving both automakers and universities, now provides comprehensive data on what factors are involved when car and driver are mutually responsible for safety. But how the manufacturers use these findings or what lawmakers will decide to do with the information is still blurry.

But will self-driving cars really be as hands-free as all that?

Under the leadership of scientists from the Technical University of Munich, more than 1,700 people tested autonomous driving in a driving simulator and sometimes directly in real motorway traffic. The car used there was equipped with systems that signaled to the driver when he or she could completely relinquish control. In some cases, the vehicle was autonomous for up to one and a half hours.

In the tests, there was always a human driver who could intervene from the passenger seat. In between, there were always situations in which the car asked the driver to take over the wheel, so the subjects experienced exactly what the next step towards self-driving cars will be.

The researchers wanted to know what happens when a person is at the wheel, but no longer has to pay attention to traffic. More specifically, how can we ensure that the driver takes command again when the technology reaches its limits?

Professor Klaus Bengler, director of the Institute for Ergonomics at TUM, puts it this way: "Are there any positive or negative effects on time management for activities that are still prohibited at the wheel, such as eating or texting?" For now, he concludes, "The magic number of seconds for all imaginable activities does not exist."

Time for a little Tetris?

The first insight from the experiments is not surprising: If the driver does not have to pay attention to the traffic and has no other demanding task, he or she becomes inattentive and lethargic after a certain time. The experts call this "automation effect." The driving tests of the Munich researchers also showed that this can be counteracted.

According to Jonas Radlmayr, who was responsible for the experiments as a research assistant, "playing Tetris" is a great way to mentally engage the driver so that he or she can quickly take over again when the car can no longer steer alone. On the other hand, activities for which the drivers holds something in both hands prolongs the takeover time and are thus not advisable. Bad news for people imagining themselves in stop-and-go traffic with a coffee mug in one hand and a cigarette in the other.

The ignorance of motorists on what we should or should not do is a serious matter.

To determine a takeover time that makes sense, the assistance system needs as much information as possible about the current state of the driver. This means, in practice, that every blink and jerk in the seat should be registered and interpreted. This is possible, for example, with sensors in the seat, which can detect, among other things, when the driver turns in a different direction and is not facing the road anymore.

The system must be so intelligent, in other words, that it knows what the driver is doing. Only then can it properly calculate an appropriate reaction time. The Ko-Haf studies found that the amount of time necessary to retake control of the vehicle depends on how challenging the situation the driver has to deal with is, making this even more complex.

"The heart of the matter is that in many cases the existing systems will work well and the drivers will feel a sense of safety that does not exist in reality," warns Klaus Bengler.

The ignorance of motorists on what we should or should not do is a serious matter. And so, for the time being — and the foreseeable future — the only reasonable approach is to keep focusing on the road.

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