In a Level 4 autonomous car  , a vehicle's automated driving system performs all driving tasks and monitors the environment. While the driver has the option to control the vehicle, the human operator, in theory, does not need to pay attention in these circumstances.

Do you think owners of a Level 4 autonomous car, however, will feel safe as the vehicle does most of the work?

Would you feel safe?

In a Webinar titled Standardization for Automated-Vehicle Testing and Simulation, a reader had the following question for two automotive industry experts:

"What is the minimal level of autonomous vehicle (AV) safety? How safe is safe enough? Level 4 is a laudable goal, however, to date, no one has come up with a safe fully automated train system. New York subways, the Washington Metro, and Amtrak trains all operate in very controlled environments. Yet, to date, they have been unable to be fully automated. Do you really believe it is possible to create a Level 4 vehicle that is acceptable to the public and why?"

Read the edited responses below from Jamie Smith, Director of Transportation Research and Design at the automated test manufacturer National Instruments, and Jeffrey Wishart, Managing Engineer at the consulting firm Exponent.

Jeffrey Wishart, Exponent

Jeffrey Wishart: This is a big question facing the automated vehicle industry. The first one, "How safe is safe enough? — that’s one that we all need to answer.

Does your automated vehicle need to be as safe as a human driver? I would guess that people are more likely to be forgiving of a human mistake than they are going to be of an automated vehicle making a mistake, so the AV probably needs to be safer.

But how much safer? Two times as safe? Ten times as safe? That’s going to require a large group of stakeholders, involving both the public and government entities coming together to make that decision. The answer may change over time, and it may be different in different parts around the world. I think it shouldn’t be a small number of people. It probably shouldn't be engineers. We need social scientists, people with lots of different perspectives, around the table to answer that question.

To the second question, I think what’s important to do is to create the performance standard and hope that will eventually result in a regulation. Then, you can see if the vehicle meets that standard, and maybe it should meet that standard before it gets deployed on public roads and commercialized.

You create the performance standard. You don’t need to say anything else necessarily on how things must be done, but you set a threshold above which the vehicles are safe to be on public roads, and below that, perhaps they aren’t.

Jamie Smith, NI

Jamie Smith: I want to go back to the question around the implementation of train systems that was submitted.

I have a high level of confidence that if a particular operator of a subway system such as the London Underground, or New York subway system, or Tokyo’s wonderful mass transit system could develop the business case to justify implementing that type of autonomous system, the technology is there to do it. But that's a wonderful point to raise, that that has yet to be done, and it’s a much simpler problem than the autonomous vehicle problem.

As we get into the Level 4 space, I have confidence that the automotive industry is going to get there. It was interesting to see what the folks attending this Webinar thought. They thought that we were at least about 10 years away from a Level 4 autonomous vehicle, [according to an audience survey presented earlier in the presentation], so that means kids in high school today should get their driver's license!

I think we’ll get there. The question is time: How long will it take for us to get vehicles on the road that we’re confident will safely get us from point A to point B?

What do you think? How long will it take before we get autonomous vehicles that make us feel safe? Share your questions and comments below.