Which safety features of the German Autobahn make it possible to have no speed limits as opposed to every other country?

One thing I haven’t seen mentioned yet is that the sections of the Autobahn with no speed limit have well-spaced interchanges (both on and off), compared to the roads in other countries. A common example I hear is that the Autobahn may have segments of 20 or 30 KM without any interchanges, while other European countries have 6 or 7 on that stretch of land. While I can’t give a concrete example of this due to unfamiliarity with the Autobahn, an article at http://www.auguszt.de/english/VZ/autobahn.html gives an example of the distance between interchanges sometimes exceeding 30 km. Meanwhile, the 26 km of the E-19 from Antwerp to Zaventem Airport (arbitrary choice based on personal knowledge) has about 10 interchanges depending on what you count as an interchange. Fewer interchanges means less merging traffic, means fewer dangerous manoeuvres, means the speed can be higher for the same risk.

Driving culture

I feel much more safe driving 170-180 on the German Autobahn than driving 120-130 on equivalent highways in other countries, especially in the East. The main reason is that the Germans keep their distance between the cars.

What I very often see in other countries, and much less often in Germany:

• tailgating but not overtaking
• joining a lane between two cars which were already too close to each other
• closing up behind the car in the front, and suddenly overtaking it in the last second
• overtaking in the right lane
• switching multiple lanes with one single motion.
• choosing a lane seemingly at random, regardless of speed or other drivers.
• cutting left curves through the lane to their left

Although probably not the main or official reason for having no speed limit, it surely contributes to not having more accidents than average, despite higher average speeds than in other countries.

In addition to the cultural aspects, there is a technical reason for autobahns being safer to drive on. The construction techniques used mean the surface is extremely consistent, with very few bumps, and a design that removes standing water. Additionally, the lanes are wider than those in many other countries with a wide shoulder – when I have driven in the Czech Republic I notice the difference at the edge of the road surface – it is not as consistent as on autobahns.

A couple of specifics:

The autobahn is 27 inches thick, or 686 millimeters thick. The life span is 40 years, compared to 20 years for the United States freeway system that is 11 inches thick.

and

The freeze-resistant concrete helps keep the road smooth. German crews routinely inspect the road network with high tech scanning equipment. When a defect is found, the entire road section is replaced.

(from allkmc.com)

I’d still put the emphasis on culture, but these technical advantages also help.

There are in fact some key features distinctive in Germany aside from having the cultural attitude:

• No garbage cans on the street. Cars must regularly be checked every two years by either the TÜV or the Dekra. Cars which do not pass may not be driven on the road.

• More demanding environment Germany has a very high car density and in contrast to the typical US checkerboard design the streets in cities are built like a maze, there are one-ways, crossings with five/sive intersections, small alleys, confusing arrangements and in some cities you have also a tram moving on the road together with the cars.

• Fahrschule: Getting the driving license is relatively expensive (1500€) and quite demanding. The training is given by certified driving instructors inside special cars which allow the instructor to brake the car if he/she sees dangerous behavior.

  • You need to make a visual test which shows that you can see clearly and distinctively even at night
  • You need to make a first aid course (not if you already made one or if you are a paramedic)

  • The theoretical course are at least 14 hours a 90 min. The final test consists of choosing 30 questions, each correct answer give a point, 20 points means a pass. Trying to learn the questions by heart is senseless because there are currently 522 questions for the basic stuff, the extended stuff has 993 questions.

  • Every trainee must absolve Sonderfahrten (special trips) which are
    at least 1 night trip (3 hours), 1 overland trip (4 hours) and 1 autobahn (5 hours).

  • The practical test itself is one official tester together with your driving instructor. The car is now unmarked. As long as no instructions are given you are driving straight. The tester may not send you into a wrong direction, but that is all. If the straight road is forbidden (one-way in wrong direction) and you try to drive, fail. If you approach a railway without looking out, fail.

  • Driving trucks is even harder, there are more restrictions and more tests.

• Verkehrsfunk: We have continous radio traffic every 30min or so which warns of traffic congestions, people or game on the autobahn, Geisterfahrer (wrong-way driver) and so on.

• Flensburg point system and the MPU. Every recorded traffic violation not only causes problems every time (fine, loss of license or even trial), the violations gain you points and once a threshold is reached, you must go to the infamous MPU (idiot test). This means a doctor examines your health and a psychologist talks with you and tries to find out if you have insight in your behavior and if your behavior will remain stable in a positive way.
  Many, many people do not pass this test.

German autobahns are not exceptionally safe

In fact, German Autobahns have mid-level safety compared to other countries, well behind countries such as the UK. The Czech Republic has particularly unsafe roads by EU standards so you are perhaps better off in Germany but your presumption that German roads are exceptionally safe is unsupported. Thus the unrestricted nature of some of Germany’s autobahns is down to history and politics not technology and safety.

I’d also note that actual travel speeds on Germany’s autobahns are not as extreme as you suggest.

On a German Autobahn, you can drive as fast as you want provided that:

• There is no specific speed limit posted; many accident-prone stretches have one.
• You can do so safely considering the condition of the road, the weather, your vehicle, and other traffic; if there is somebody on the left lane of the Autobahn at a mere 150 kph it is your job to slow down.

Regarding safety, it certainly helps that German drivers are used to speeds in excess of 130 kph. If you haven’t done it before, 200 kph is frightening. If you are on a three-lane-per-direction highway and the other guys in the leftmost lane are all doing 200 kph, you just go with the flow, and pass motorists who are doing 130 mph in the middle lane. Just watch out for those people who pull into your lane at a mere 150 kph …

If you want to go 280 kph, there are a couple of stretches where it can be safely done, on a Sunday morning (few trucks) on a sunny summer day (dry and bright).

A few things might contribute to make it possible:

• There are speed limits, a lot of them. There are speed limits around cities, before interchanges, in areas with a lot of traffic or many curves, etc. Increasingly, you will see road sections with dynamic speed limits being turned on or off depending on the conditions. So even in Germany there is an awareness that speeding can be dangerous, people do not speed to the same extent everywhere.
• You’re still responsible for your speed. There are no special safety features, no broader curves or anything like that. If anything, Germany has been underinvesting in its infrastructure and road surface tends to be worse than in neighbouring countries. But drivers are aware that some cars will be very very fast, which might alleviate the danger if you compare it to illegal speeding in other places.

But the key is that nobody knows what the effect on safety is and there are many reasons to think it does have a negative effect overall. All you can say is that it’s not dramatically worse to the point that Germany would be much more dangerous than other European countries.

Historically, the number of deaths on the road (appropriately normalised) tended to be lower than in other countries, which specialists explained mostly through the higher traffic density (more cars on the road means more traffic jams and therefore less deadly accidents). Now, it’s in the middle of the pack, not much more dangerous than other European countries and certainly safer than, say, North Africa, but not especially safe either.

The thing is that it’s a game of numbers, cars don’t break down when you pass 140 km/h in another country and in fact you can find many countries in the world with worse road infrastructure and lax rules (or strict rules that aren’t enforced). So everything is “possible”, it will just make road slightly safer or slightly more dangerous.

And, ultimately, the issue is highly politicised and, AFAIK, no separate statistics are available on non-limited stretches of motorway (which would be necessary to make a head-to-head comparison or try to model the effect of speed limits).

TL;DR: It’s religious cultural.

A considerable portion of Germans consider the absence of a general speed limit a fundamental freedom and will strongly argue against any suggestions to abolish it. If a politician or political party were to suggest a general autobahn speed limit, they would lose a considerable number of votes – which is why it does not happen. I have experienced that even with very reasonable people (including university professors and legal professionals), it can be impossible to have a reasonable discussion about this topic. Note that this also applies to much higher limits than 130 km/h. As an example, see the discussion on this answer.

This has often been compared to US weapon laws and bullfighting in Spain. If you speak German, this article in a prominent German online newspaper seconds my assessment.
The answers to this question also contain a few documents sharing this assessment.

Of course it should be noted that the quality of German highways allows for the laws to be like this without a considerable number of accidents or deaths, and speed limits on highways do exist when the quality of the road or other circumstances would make no speed limit even less advisable.