Drivers can breathe easy: probably no blow-up danger on motorways

The summer heat can suddenly crack freeways. Then there is danger to life for road users. But in 2022 the situation seems to have eased.

The first heat wave of the year is here. In previous years, this meant mortal danger for car drivers and especially motorcyclists on some German autobahns. But in 2022 the situation appears to be more relaxed.

In the meantime, the highway maintenance departments have prepared the well-known endangered sections of the highway as a preventive measure, as reported by Bayerischer Rundfunk. The concrete ceilings have been cut open at regular intervals over the last few years and the workers brought asphalt into these relief cuts. I can expand the asphalt, which relieves the concrete slabs and thus prevents life-threatening blow-ups. In addition, the highway maintenance departments regularly carry out inspections on the highway sections in question. So by 2022 the situation should be under control. As early as 2021 there were no more blow-ups in southern Bavaria, so the measure with the relief cuts seems to be effective.


Nevertheless, always pay attention to corresponding announcements in traffic radio and corresponding warnings on the Internet.

Blow-ups can only occur on concrete highways. You can read more about the technical background and developments in recent years here:

Background: The blow-up development since 2021

With increasing heat, a danger for motorists and motorcyclists in particular returned in 2021: blow-ups, i.e. bursting freeways with roadways made of concrete elements. This problem does not only exist in the particularly hot states in the southwest of the USA, such as this tweet

but also in Germany.

Road users should therefore be particularly careful and ready to brake on (mostly older) motorways with concrete lanes on hot summer days. Follow the traffic news for relevant clues. In addition, you may have to reckon with temporary speed limits – the motorway maintenance departments and police want to reduce the risk of accidents on endangered sections.

In the past, however, the highway maintenance departments have taken measures against the danger of blow-ups. Relief cuts were made on many lanes, which are then filled with asphalt.

If you discover blow-ups while driving that do not yet appear in the traffic reports or in the real-time traffic information from Tomtom, Garmin, Here or Google Maps and Apple Maps, then inform the police.

Blow-Ups: Development in the years 2014 to 2018

In July 2018 it was that time again: We had hardly had several hot summer days in a row when the motorway maintenance departments had to put speed limits on some concrete sections of the motorway. In Baden-Württemberg, for example, there was a speed limit of 80 km/h for selected sections on the A81 and A7, because the heat could cause the concrete roadway to bulge there. According to SWR3, the speed limit applied to these sections: “A81 between the Weinsberg motorway junction and the Jagsttalbrücke Widdern (both in the Heilbronn district) in both directions. Also the area between the Boxberg (Main-Tauber-Kreis) and Osterburken (Neckar-Odenwald-Kreis) junctions ) affected in the north direction. On the A7, the maximum speed allowed will initially be reduced in both directions between Ulm and Kreuz Feuchtwangen (Bavaria). The speed limit applies until Sunday from 10 a.m. to 8 p.m. According to the Stuttgart regional council, a section south of the Junction Westhausen (Ostalbkreis), here the speed could be throttled from Thursday.”

On the other hand, on the A93 (south of Regensburg), which has been a problem child in terms of blow-up danger in recent years and on which there was a fatal accident in 2013 due to a blow-up – see below in this report – this was the case year no danger. The Autobahn-Meisterei had had many relief cuts made on the road surface in recent years to prevent the sudden bursting. That was different in the years before: On the A93, for example, the motorway maintenance department discovered a bump in the roadway between the Abensberg and Hausen junctions in the direction of Regensburg. About a kilometer before the Hausen exit. There was a speed limit of 80 km/h. And in 2014, the first somewhat summery day was enough for the road surface to burst open on the A3 autobahn near Metten in Lower Bavaria in the direction of Regensburg. Nobody was injured at the time, and construction work intended to prevent a blow-up may have been the reason for the bursting open.


It is best to find out before starting your journey on the websites of the traffic situation services or on the websites of the regional press whether there is a speed limit on the motorway you are driving on because of the risk of blow-ups and then drive off earlier if necessary. Navigation devices with real-time traffic information such as the TomTom Go Camper or the Garmin Nüvicam or navigation apps such as Google Maps or Here We Go or factory-installed navigation systems such as Connected Drive from BMW or the Discover Pro from VW also indicate these speed limits and take into account the delays caused by this when calculating the arrival time.

Blow-up: That’s what it’s all about and that’s why it’s so dangerous

After the low temperatures in winter, the intense summer heat (partly in combination with the still quite cool ground) causes the road surfaces to burst open in many places in Germany. In this context, experts speak of so-called blow-ups. The road surface rips open within a few seconds and part of the torn-off road surface rises. And thus forms a kind of ski jump from which the cars, trucks and motorcycles driving over it really take off.

Incidentally, the problem in this way only affects roadways that are made of concrete slabs.

Asphalt road surfaces can also show changes under the influence of extreme heat, such as ruts, but they do not burst open as dangerously.

2013 on the A93: Fatal accident due to blow-up

Exactly such a blow-up happened in 2013 on the A93 motorway from the Hallertau motorway junction in the direction of Regensburg, almost exactly at the level of the Abensberg motorway exit. There, a BMW, a Fiat, a panel van and a Porsche turned into flying projectiles until finally a Harley-Davidson driver took off. And fell so badly that he died as a result. The skid marks left by the drivers involved in the accident could still be seen on the motorway surface for many months. The Autobahn-Meisterei pulled the emergency brake and imposed a speed limit on the affected section of the road.

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Drivers are almost helpless against such blow-ups, as the road surface rises or falls within a few seconds. The only protection: Drive slower than usual, so that if you fall, you might still be able to stop in time in front of the cliff edge, or at least drive over the cliff edge at a significantly reduced speed – and then accordingly not take off so much.

According to the ADAC, around 70 percent of the autobahns in Germany are made of asphalt, and around 30 percent are concrete lanes. According to the ADAC, there are problems especially on older concrete routes. This type of damage usually occurs primarily during prolonged periods of heat.

Who is liable?

The ADAC points out that in the event of accidents or damage to the vehicle caused by blow-ups, the injured party must prove that the responsible highway maintenance department has not complied with their duty to ensure road safety. This should be very difficult in view of the often spontaneously occurring bulges. This means that motorists have no choice but to slow down, increase the distance to the vehicle in front and report damage immediately, as recommended by us above.

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