[rndn]

In my experience there is no significant difference between an Autobahn and a North American highway regarding the difficulty of navigation. The tricky parts are the ramps, exits, construction zones and merging, and they occur roughly with the same frequency.

I think the test track is more about testing technology which will be installed at the roadside.

[DasIch]

Speaking as a German who spend quite some time driving in other European countries with speed limits, the difference is massive.

Elsewhere most people tend to drive at more or less at the maximum speed allowed. This makes for a very relaxed, easy albeit boring experience.

In Germany the difference in speed between the cars are a lot bigger, even in areas with a speed limit. In combination with the Rechtsfahrgebot (a law that makes driving in the right-most lane mandatory, unless you are overtaking or there is no space) you are constantly overtaking trucks and other cars, while others do so to you as well. Overtaking itself requires accelaration often time going beyond the actual speed limit so as not to slow down others too much which can be dangerous.

Furthermore you have to constantly monitor traffic so as not to be trapped on the right lane, if a larger group of cars comes up from behind, which happens frequently.

I highly doubt that current autonomous cars are capable of that to a degree, where I wouldn't be annoyed and wanted to take over. Especially at night, when it's raining, snowing, there is fog or a combination of these.

[joezydeco]

At least German drivers are predictable when it comes to Rechtsfahrgebot.

Contrast with American drivers, who will stay in whatever lane they want and/or pass at high speed in any lane they deem open.

[DasIch]

Maybe my standards are too high but whenever I'm driving on the autobahn I get the expression that some drivers didn't get the memo about the Rechtsfahrgebot.

[rndn]

It would be actually interesting to hear about this difference from someone who is working on autonomous cars for both highways and Autobahns. I still wouldn't call the difference 'massive' (at least not in terms of how much the technology would need to advance). Overtaking and avoiding slows down is an issue on highways in other countries too and once it is implemented it could possibly be easily adapted to traffic moving at a faster pace. Being trapped on the right lane happens quite often, but you generally have this problem when the current lane is crowded. It's not a special case for the Autobahn. I agree that the speed difference can be much higher which would possibly require a ToF sensor with higher range than what is currently built into the Google cars (only about 200 m).

[psycovic23]

I do work on this. Your last point is correct (and probably the biggest issue). Others include weather and general vision problems.

[jacquesm]

Speed.

Going 100 mph plus in the left lane on the German autobahn you'll be the recipient of flashing signals of grandmothers passing you at 120 if you don't get out of the way fast enough.

[cjbenedikt]

There is though: there is no speed limit on German Autobahns

[arrrg]

The only hard part about that is avoiding cars coming at high speeds from behind. (Though usually these people will be used to slowing down and they actually have to slow down if the car in front of them is legitimately overtaking another one The main responsibility to keep everyone save lies with the fast driving car on the left lane and with cars changing lanes to insure that they are not blocking someone else. Since autonomous cars have no blind spot and should be quite good at estimating distance and speed, presumably better than humans, that should really not be an issue.)

It's not as though you have to drive fast. Most people actually don't drive super fast, they stick to 130 to 160 km/h. You will only occasionally encounter someone going way beyond that. Just because there's no limit doesn't mean people drive at speeds they are uncomfortable with … extended periods at 160 or beyond make me queasy and I tend to stick to 140 or so. That also gets better mileage.

[this_user]

There is no general speed limit but most portions do actually have specific limits.

[joezydeco]

And it's dynamic. Portions will switch from unlimited to limited speed based on weather, construction, or accidents far ahead, giving everyone time to slow down and merge away from a blocked lane.

And drivers actually follow the signs. As an American driver it's an amazing thing to see.

[Argorak]

> And drivers actually follow the signs. As an American driver it's an amazing thing to see.

Speed control flashes are a common sight :).

[joezydeco]

You mean the ones that result in a ticket being sent to the rental car agency in the driver's name? Never heard of them. =)

[TkTech]

This doesn't matter at all to Google's cars. They are designed to ignore the speedlimit in favour of the real speed of traffic around it[1], as it has been proven to be far safer than slowing down. It's currently caped at 16km/h over but this is an arbitrary limit.

1: http://www.bbc.com/news/technology-28851996

[lttlrck]

It must matter when there are only Google cars present.

[pests]

That is actually a pretty interesting point you've made.

[mikeash]

Yeah, it's a good one to think about. I imagine massive swings in traffic speed with a frequency of a few minutes as the cars get into various interesting feedback loops.