Instruct: Given a question, retrieve relevant passages that answer the question.
Query: What's the speed limit on the autobahn?
General speed limits in Germany are set by the federal government. All limits are multiples of 5km/h. There are two default speed limits: 50km/h (31mph) inside built-up areas and 100km/h (62mph) outside built-up areas. While parts of the autobahns and many other freeway-style highways have posted limits up to 130km/h (81mph) based on accident experience, congestion and other factors, many rural sections have no general speed limit. The German Highway Code (Straßenverkehrsordnung) section on speed begins with the requirement [1] which may be rendered in English:
Some cars with very powerful engines can reach speeds of well over 300km/h (190mph). Major German car manufacturers, except Porsche, follow a gentlemen's agreement by electronically limiting the top speeds of their cars—with the exception of some top of the range models or engines—to 250km/h (155mph).[32] These limiters can be deactivated, so speeds up to 300km/h (190mph) might arise on the German autobahn, but due to other traffic, such speeds are generally not attainable except during certain times like between 10 p.m. and 6 a.m. or on Sundays (when trucks drivers have to rest by law). Furthermore, there are certain autobahn sections which are known for having light traffic, making such speeds attainable during most days (especially some of those located in Eastern Germany). Most unlimited sections of the autobahn are located outside densely populated areas.
In a variance to the general Austrian motorway speed limit of 130 km/h (81 mph), a special environmental speed limit of 110 km/h (68 mph) is in force on the Tauern Autobahn between 10:00 PM and 5:00 AM.
The autobahns of East Germany (GDR) were neglected in comparison to those in West Germany after 1945. East German autobahns were used primarily for GDR military traffic and for state-owned farming or manufacturing vehicles. The speed limit on the GDR autobahns was 100 kilometres per hour (62mph); however, lower speed limits were frequently encountered due to poor or quickly changing road conditions. The speed limits on the GDR autobahns were rigorously enforced by the Volkspolizei, whose patrol cars were frequently found hiding under camouflage tarpaulins waiting for speeders.
"Roads with no possibility of a side impact or frontal impact" are sometimes designated as Type 1 (motorways/freeways/Autobahns), Type 2 ("2+2 roads") or Type 3 ("2+1 roads"). These roadways have crash barriers separating opposing traffic, limited access, grade separation and prohibitions on slower and more vulnerable road users. Undivided rural roads can be quite dangerous even with speed limits that appear low by comparison. For example, in 2011, Germany's -limited rural roads had a fatality rate of 8.7 deaths per billion travel-km, over four times higher than the autobahn rate of 2 deaths. Autobahns accounted for 31% of German road travel in 2011, but just 11% (453 of 4,009) of traffic deaths.
"Autobahnähnliche Straßen" mostly are colloquially referred to as "gelbe Autobahn" (yellow motorway) because they have the same technical standard as the "Autobahn" but have black on yellow signs instead of the white on blue signs used on the "Autobahn" motorway network. These are generally high-speed arterial roads in larger cities or important roads within a federal state that do not connect to major cities, so that they do not fall under the federal budget for the "Autobahn" network. The federal road Bundesstraße 27 is an example where about half of its length is upgraded to a high speed motorway standard. On the basis of their structure these roads have, comparable to the German "autobahn", the legal foundation that no default speed limit exists (design speed 130 km/h), although the standard advisory speed limit () still exists. Nevertheless expressways are often given speed limit signs.
At the moment some (blue) motorways have been taken out of the "Autobahn" network programme but still have the blue signs; and on the other hand some former non-"Autobahn" (yellow) motorways have been added to "Autobahn" budgeting but the signs have not been changed either. Motorways that are neither in the "autobahn" network nor in the "Bundesstraße" network are given black on white signs, following the same sign code as high-speed dual carriageways—this is mostly seen on urban trunk roads.
Germany's autobahns are famous for being among the few public roads in the world without blanket speed limits for cars and motorcycles. As such, they are important German cultural identifiers, "... often mentioned in hushed, reverential tones by motoring enthusiasts and looked at with a mix of awe and terror by outsiders."[1] Some speed limits are implemented on different autobahns.[25]
German manufacturers initially started the "gentlemen's agreement", electronically limiting their vehicles to a top speed of , since such high speeds are more likely on the Autobahn. This was done to reduce the political desire to introduce a legal speed limit.
Some limits were imposed to reduce pollution and noise. Limits can also be temporarily put into place through dynamic traffic guidance systems that display the according message. More than half of the total length of the German autobahn network has no speed limit, about one third has a permanent limit, and the remaining parts have a temporary or conditional limit.
Road speed limits are used in most countries to set the maximum (or minimum in some cases) speed at which road vehicles may legally travel on particular stretches of road. Speed limits may be variable and in some places speed is unlimited (e.g. on some Autobahn sections in Germany). Speed limits are normally indicated on a traffic sign. Speed limits are commonly set by the legislative bodies of nations or provincial governments and enforced by national or regional police or judicial bodies. Even with the minimum speed limit, that violator is punished. 
There is a general speed limit of 80km/h (50mph) for trucks with a GVWR over 3,500kg (7,716lbs) and for vehicles with trailers. For vehicles with a GVWR of over 7,500kg (16,534lbs) the limit is set to 60km/h (37mph) except on autobahns (also 80km/h).[26] For coaches and cars with trailers the limit is increased to 100km/h on autobahns (under certain requirements).[27] Posted speed signs for trucks are not common, they can be seen on some dangerous curves or descents.
Investigation sections probe crime at rest stops and the movement of criminals and smugglers on the "Autobahn", often together with German Customs. The "Autobahnpolizei" also use fast unmarked vehicles with video cameras discreetly mounted front and back to follow and film reckless drivers and speeders. Approximately 30% of autobahns in Germany have a permanent speed limit of or less, primarily in urban areas. On the remainder, the 130 km/h speed limit is only advisory.
The Richtgeschwindigkeit (German Advisory or Suggested Speed of Travel) is a legal term in Germany describing the advisory speed limit for roads without a mandatory speed limit. Autobahns have an advisory speed limit of on non-signposted sections.
The first maximum speed limit was the limit introduced in the United Kingdom in 1861. The highest posted speed limit in the world is , which applies to some motorways in UAE. However, some roads have no speed limit for certain classes of vehicles. Best known are Germany's less congested Autobahns, where automobile drivers have no mandated maximum speed. Measurements from the German state of Brandenburg in 2006 showed average speeds of on a 6-lane section of autobahn in free-flowing conditions. Rural roads on the Isle of Man and the Indian states of Andhra Pradesh, Maharashtra, and Telangana, also lack speed limits.
The following tables show various jurisdictions' default speed limits (where applicable) that apply to different types of vehicles travelling on three different types of road. Actual speed limits may range beyond these values. Speeds are listed in kilometers per hour. The enforcement tolerance is specified in km/h or percentage above the stated limit. For the United Kingdom and the United States, the speed limit listed in miles per hour. Germany, with its Autobahns, is the only country without a general speed limit on its highways. The Isle of Man is the only jurisdiction without a general speed limit on rural two-lane roads.
In Germany, the "Autobahn-Richtgeschwindigkeits-Verordnung" (Directive on Reference Speed on Motorways), introduced in 1974, recommends a speed of no more than for autobahns and similar roads, whose lanes are separated by a median or which have at least two lanes per direction, provided there are no traffic signs posting a lower speed limit.
Typically motorways have higher speed limits than conventional roads because motorways have features which decrease the likelihood of collisions and severity of impacts. For example, motorways separate opposing traffic and crossing traffic, employ traffic barriers, and prohibit the most vulnerable users such as pedestrians and bicyclists. Germany's crash experience illustrates the relative effectiveness of these strategies on crash severity: on autobahns 22 people died per 1000 injury crashes, a lower rate than the 29 deaths per 1,000 injury accidents on conventional rural roads; however, the rural risk is five times higher than on urban roads – speeds are higher on rural roads and autobahns than urban roads, increasing the severity potential of a crash. The net effect of speeds, crash probability, and impact mitigation strategies may be measured by the rate of deaths per billion-travel-kilometers: the autobahn fatality rate is 2 deaths per billion-travel-kilometers, lower than either the 8.7 rate on rural roads or the 5.3 rate in urban areas; the overall national fatality rate was 5.6, slightly higher than urban rate and more than twice that of autobahns.
Signposting of advisory speed limits varies from country to country; Australia makes extensive use of advisory speed limits across its highway networks while the "Richtgeschwindigkeit" ("reference speed") in Germany is valid for the whole autobahn network (but can be overruled by speed limits in particular sections or for special reasons like weather conditions or roadworks), while the United States and the United Kingdom only give advisory speed limits for hazards such as bends.
In the mid-1980s, acid rain and sudden forest destruction renewed debate on whether or not a general speed limit should be imposed on autobahns.[55][56] A car's fuel consumption increases with high speed, and fuel conservation is a key factor in reducing air pollution. Environmentalists argued that enforcing limits of 100km/h (62mph) limit on autobahns and 80km/h (50mph) on other rural roads would save lives as well as the forest, reducing the annual death toll by 30% (250 lives) on autobahns and 15% (1,000 lives) on rural roads;[57] the German motor vehicle death toll was about 10,000 at the time.[58] The Federal Government sponsored a large-scale experiment with a 100km/h (62mph) speed limit in order to measure the impact of reduced speeds on emissions and compliance.[59] Afterward, again, the Federal Government declined to impose a mandatory limit, deciding the modest measured emission reduction would have no meaningful effect on forest loss.[60] By 1987 all restrictions on test sections had been removed, even in Hesse where the state government was controlled by a "red-green" coalition.[61]
Just prior to the 1973 oil crisis, Germany, Switzerland,[44] and Austria[45][46] all had no general speed restriction on autobahns. During the crisis, like other nations, Germany imposed temporary speed restrictions; for example, 100km/h (62mph) on autobahns effective 13 November 1973.[47] Automakers projected a 20% plunge in sales, which they attributed in part to the lowered speed limits.[48] The 100km/h limit championed by Transportation Minister Lauritz Lauritzen lasted 111 days.[49] Adjacent nations with unlimited speed autobahns, Austria[45][46] and Switzerland,[44] imposed permanent 130km/h (81mph) limits after the crisis.
German national speed limits have a historical association[33] with war-time restrictions and deprivations, the Nazi era, and the Soviet era in East Germany. "Free driving for free citizens" ("freie Fahrt für freie Bürger"), a slogan promoted by the German Auto Club since the 1970s,[34] is a popular slogan among those opposing autobahn speed restrictions.[35][36][37] Tarek Al-Wazir, head of the Green Party in Hesse, and currently the Hessian Transport Minister has stated that "the speed limit in Germany has a similar status as the right to bear arms in the American debate... At some point, a speed limit will become reality here, and soon we will not be able to remember the time before. It's like the smoking ban in restaurants."[38]
In 2014, the conservative-liberal ruling coalition of Saxony confirmed its rejection of a general speed limit on autobahns, instead advocating dynamic traffic controls where appropriate.[74] Between 2010 and 2014 in the State of Hesse, transportation ministers Dieter Posch[75] and his successor[76] Florian Rentsch,[77] both members of the Free Democratic Party, removed or raised speed limits on several sections of autobahn following regular 5-year reviews of speed limit effectiveness; some sections just prior to the installation of Tarek Al-Wazir (Green Party) as Transportation Minister in January 2014[78][79] as part of an uneasy CDU-green coalition government. In 2015, the left-green coalition government of Thuringia declared that a general autobahn limit was a Federal matter; Thuringia would not unlaterally impose a general Statewide limit, although the Thuringian environmental minister had recommended a 120 kilometres per hour (75mph) limit.[80]
In December 1952 the West German legislature voted to abolish all national speed limits, seeing them as Nazi relics,[42] reverting to State-level decisions. National limits were reestablished incrementally. The 50km/h (31mph) urban limit was enacted in 1956, effective in 1957.[43] The 100km/h (62mph) limit on rural roads—except autobahns—became effective in 1972.
Germany's network of controlled-access expressways includes all federal Autobahnen and some parts of Bundesstraßen and usually no Landesstraßen (State Highways), Kreisstraßen (District Highways) nor Gemeindestraßen (municipal highways).
The federal "Autobahn" network has a total length of in 2014, making it one of the densest networks in the world.
The German autobahns have no general speed limit (though about 47% of the total length is subject to local and/or conditional limits), but the advisory speed limit ("Richtgeschwindigkeit") is . The lower class expressways usually have speed limits of or lower.
In 1973, in the wake of the 1973 oil crisis, a federal speed limit of 100km/h (62mph) on Autobahns was imposed to help conserve fuel for fear of impending future shortages (not for environmental or safety reasons). The measure only lasted from December 1973 to March 1974; while the administration and the Bundestag were in favor of keeping the speed limit, the Bundesrat pushed to repeal the law. As a compromise, a recommended speed was introduced on Autobahns and "highways outside of built-up areas with a center divide or without a center divide and a continuous lane for overtaking in both directions". This law is basically still in effect today. Unrestricted non-Autobahn highways, however, have since become virtually non-existent or replaced by Schnellstraßen, Autobahn-like expressways typically limited to 120 or 130km/h and normally only covering a few kilometers.