Tanneberger Hole

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On the right the new motorway from a bird's eye view, on the left the old route in the Tanneberger Loch, which can still be seen very clearly in this picture from 2010.
Hardly used motorway in Tanneberger Loch in October 1982, looking east
Old motorway in Tanneberger Loch 34 years later from the same location, looking east

As Tannenberger hole , named after the nearby village of Tannenberg , a former section is Bundesautobahn 4 in Saxony between Dresden and Chemnitz referred. The motorway crossed the Triebisch valley there . Known for steep gradients and as a hotspot for accidents, the Triebisch valleys were planned and implemented for the area in the 1990s . Since 1999, the motorway has been running a little further north and bypassing the Tanneberger Loch on several valley bridges .

location

The Tanneberger Loch is located in the center of Saxony in the extreme south of the Meißen district , about eleven kilometers west of the Dresden city limits and 22 kilometers as the crow flies from Dresden city center. The river Triebisch, coming from the Tharandt forest , flows roughly northwards in the direction of Meißen , where it flows into the Elbe , in a narrow valley cut 50 meters deep into the Meißner highlands .

Former route of the motorway

The A 4 runs in the area in an east-west direction between the Wilsdruff motorway exit and the Nossen motorway triangle , where the federal motorway 14 branches off to Leipzig . The old route separates in the direction of Chemnitz from the new section about two kilometers north of the Blankenstein location or 4.5 kilometers west of the Wilsdruff radio tower , a well-known landmark . Initially, the motorway ran here with a steep gradient to the southwest and made a right-hand bend until it reached the bottom of the valley. In the Triebischtal itself, the route went straight for almost a kilometer and crossed the winding Triebisch three times. Between the first two crossings there was a small parking lot with no deceleration or acceleration lane - there was no parking space in the opposite direction. At the third crossing, just before leaving the depression, the route swung into a left curve. In the narrow Krebsgrund, a left side valley of the Triebisch valley, it led back up into the highlands. Once there, about one kilometer south of the Rothschönberg location , the old route runs for two kilometers a few meters south of the new one, until both meet again directly at the Nossen triangle.

History of the motorway route in the Tanneberger Loch

Motorway construction in the 1930s

The motorway - here a map almost a century before it was built - led through the side valley north of the Hirschelberg down to the Triebisch, followed its valley to the north of Tanneberg and then turned half-left into the Krebsgrund. It continued past the cow puddle and the tube well.

In connection with the construction program for various Reichsautobahns in the 1930s , the National Socialists also pursued the plan of an east-west connection from Upper Lusatia to Hesse , to the major Thuringian cities such as Erfurt , Gera and Jena as well as the major Saxon cities of Chemnitz and Dresden should be connected. The “ Supreme Construction Management of the Reichsautobahn ” (OBR) Dresden responsible for Saxony finally initiated the construction of the 83 Dresden – Chemnitz – Meerane route planned by the “Society for the preparation of the Reichsautobahn” (GeZuVor) . The first groundbreaking was on March 21, 1934 at the Dresden-Altstadt junction 15 kilometers east of the Tanneberger Loch. From there the construction continued to the west.

The highways have been artfully inserted into the landscape. In the highlands between Dresden and Nossen, most of the autobahn could be led straight on by the fastest route, even if it sometimes required larger engineering structures. A few kilometers west of the Tanneberger Loch, the Siebenlehn motorway bridge was built , which at the time of construction was 70 meters above the valley floor and was the highest in Europe. The comparatively wide valley of the Wilder Sau near Wilsdruff, where the Saubachtal bridge was built, and the bridging of the Kleine Triebisch near Birkenhain did not require any sharp turns. But planning on the Große Triebisch turned out to be more difficult, because the Tanneberger Loch was a deep, branched and narrow incision, but was partly along the planned route. A planning office developed two variants: One contained a bridge over the Triebischtal north of Neutanneberg and the further course south of Alttanneberg and Rothschönberger Tännicht, which would have met the current route just west of the Nossen autobahn triangle between Deutschebora and Hirschfeld .

For reasons of cost, however, the other variant was implemented: Two small side valleys served as ramps down to the Triebisch and up again. The existing landscape forms were cleverly used for the construction of the motorway and after completion offered a successful change from the sections on the plateau. This created a very distinctive route. The road followed the course of the valley and the two directional lanes ran in sections on the inclines at different altitudes. In the Triebischtal a bridge was built for the road from Tanneberg to Groitzsch and a small passage so that the farmers could continue to cultivate their meadows on the other side of the motorway. Newly created embankments were not greened, but left to natural succession .

Adolf Hitler opened the Dresden – Meerane autobahn and thus the section through the Tanneberger Loch on June 25, 1937 with an inauguration drive. In a traffic count at the nearby Saubachtal Bridge on Whit Sunday, June 4, 1938, 4728 cars, 2384 motorcycles, 46 trucks and 34 buses used the motorway. This route - four lanes and without slow lanes or hard shoulder lanes - remained largely unchanged in the time of the GDR due to a lack of urgent needs and financial means. At the western end, the Nossen junction was built until 1971 in connection with the construction of the Leipzig- Grimma- Nossen autobahn, and the concrete ceiling was renewed shortly before the fall of the Wall in the GDR .

Development in the 1990s

In the 1990s, a route relocation became necessary for various reasons, including structural, safety and ecological aspects.

For a long time since it opened in the 1930s, traffic has increased slowly but steadily. In addition, the vehicles were not as fast until the end of the GDR, so the motorway was sufficient. After the reunification and the associated increased permeability of the European internal borders as well as the German reunification, the traffic on this important connecting route between Eastern and Western Europe, the Europastraße 40 , increased dramatically. The Tanneberger Loch is even at a focal point, namely in the busy section of the A4, on which the traffic from Dresden towards Leipzig and Chemnitz and the other way round is bundled. It is only unbundled at the Nossen triangle, where the A 14 branches off to Leipzig.

At the beginning of the 1990s, the existing car park on the Triebisch in the direction of Chemnitz was closed. The lack of deceleration and acceleration lanes made it a major safety risk. The two tight bends as well as the uphill and downhill stretches of up to six percent, which are extreme for a motorway, no longer complied with the applicable guidelines. Furthermore, the microclimatic conditions of the river valley had a negative impact on traffic, including more frequent fog formation and wetness or freezing of the roadway.

With a traffic load of more than 40,000 vehicles per day, the Tanneberger Loch developed more and more into a bottleneck. An analysis by IVV Aachen in 1991 predicted a traffic volume of 64,000 vehicles per day for 2010 (according to automatic traffic counts from 2010, the actual value was then almost 80,000 vehicles per day, which smaller-scale analyzes had already predicted in the 1990s). This made it necessary to expand the entire motorway from Eisenach to Görlitz as part of the German Unity Transport Project (VDE) number 15. In this context, the replacement of the old route in Tanneberger Loch was also carried out. Further route relocations as part of the expansion of the A 4 are the northern relocation near Eisenach and the northern relocation with tunneling near Jena . The further construction of the A4 from Weißenberg to Görlitz caused a deviation from the original, prepared Reichsautobahntrasse in the Königshain Mountains area .

Until the inauguration of the new route in 1999, the volume of traffic at peak times clearly exceeded the load limit - with an average of 66,000 vehicles per day and a heavy haulage share of 20.5 percent, it was already higher than the value forecast for 2010. The result was that disabilities, traffic jams and accidents, especially caused by slow-moving trucks, were the order of the day at Tanneberger Loch. For this reason, after a speed limit of 100 km / h had not brought the desired success, a computer-controlled traffic control system with variable message signs was installed in 1995 to increase safety for 5.6 million DM (around 2.9 million euros) Traffic volume displayed adjusted speed limits. Nevertheless, in 1997 there were 64 serious accidents with 57 injured and one fatality on the section of just a few kilometers, in 1998 there were 60 serious accidents with 35 injured and one fatality.

Another reason for the route relocation was the considerable environmental pollution. Due to the steep inclines, many vehicles drove the route at full throttle, consumed more fuel and emitted many pollutants. The fresh air supply in the narrow valley was problematic anyway. The ecological balance of the idyllic biotope in the middle of the landscape protection area (LSG) Triebisch valleys was visibly disturbed. The two side valleys in the sensitive natural area, which served as ramps, were completely built over. An expansion of the existing route with modern routing parameters would have required mighty dams and strong cuts in the valley area of ​​the Triebisch, including clearing of wooded slopes. A new building, on the other hand, could be carried out on previously agriculturally used areas on the plateau. The subsequent unsealing and renaturation of the old route made it possible to reconnect habitats for flora and fauna that had been interrupted for decades.

New line

Map of the area around the Tanneberger Loch. Red: old route; blue: new line.

The first planning work began in December 1991. An in-depth investigation carried out in March 1993 into the routing of the Triebisch valleys was ultimately decisive for the re-routing. The planning approval procedure started in autumn 1994. The construction work ran from 1996 to 1999. On January 12, 1999, the then Saxon Minister of Labor and Economics Kajo Schommer inaugurated the Dresden – Chemnitz carriageway. The inauguration ceremony had started late, as the guests were stuck in a traffic jam because of a truck stuck on a slope out of Tanneberger Loch. On the half of the route leading to Chemnitz, four narrowed lanes were set up, two of which went into operation on January 12th. At the end of February 1999, traffic in the opposite direction to Dresden was moved to the new route.

Since the opening of the eastbound half of the route on December 1, 1999, traffic has been running in six lanes. The number of accidents fell significantly after the relocation, but the volume of traffic continued to rise. An automatic counting station of the Federal Highway Research Institute (BASt) in the area of ​​the Triebisch valleys recorded exactly 71,737 vehicles within 24 hours with a heavy goods vehicle share of 16.1 percent. In 2007, these values ​​had risen to 80,270 vehicles and 18.2 percent of the heavy goods vehicle, in 2015 they were 88,933 vehicles and 19.2 percent, and in 2017 they were 95,819 vehicles and 21.3 percent. As a result of the route being relocated from the valley to the plateau, road traffic noise increased in Tanneberg, Rothschönberg and Groitzsch .

The replacement line itself is part of a 7.9-kilometer planning section between operating kilometers 31.5 and 23.6, in which, in addition to three valley bridges, eight smaller overpasses or underpasses were required. It bypasses the Tanneberger Loch just north on the plateau. This reduces the gradient from 6 to a maximum of 1.8 percent. The lines have been straightened, generous peaks and troughs rounded and the curve radii enlarged. A total of around one million cubic meters of earth was moved during the construction, with the amount of material removed in incisions roughly equaling the amount applied for dams. Ten rain retention basins were created to collect and clean the surface water of the roadway. The new route is no longer designed with four lanes, but contains six lanes plus hard shoulder. The construction costs totaled 131 million DM (around 67 million euros). Of this, 60 million DM (around 31 million euros) went to the three large valley bridges over the Triebischseitental of the Schmiedewalder Dorfbach, the Triebisch itself and the Tännichtbach further west. They each consist of two separate superstructures that are prestressed to a limited extent lengthways and transversely.

Triebischseitental Bridge

The construction of the new line began in June 1996 with the Triebischseitentalbrücke, which runs over the Schmiedewalder Bach flowing into the Triebisch. This prestressed concrete structure is the easternmost of the three large structures and is 330 meters long, 37 meters wide at the highest pillar, 43 meters high. The 3.58 meter high superstructure, produced using the incremental launching method, is a continuous beam over seven fields. The middle field has a span of 58 meters, the two outer fields are 40 meters long, the other four are 48 meters long.

Triebischtalbrücke

Triebischtalbrücke

The middle of the three bridges, the Triebischtalbrücke, is the largest with a length of 424 (north bridge) or 427 meters (south bridge) and a maximum height of 47 meters and sets a clear accent in the landscape of the Triebischtal. The trumpet-shaped column heads at the upper end of their reinforced concrete hollow pillars are striking , the width of which more than doubles to nine meters to make maintenance work easier. Albert Speer junior's architectural office helped to find the shape of the bridge piers. The box cross-section of the superstructure has a construction height of 4.88 meters. The span between the pillars is 72 and 84 meters respectively. The valley area remains open and permeable. This bridge was also built using incremental launching. To do this, the corresponding system pushed the superstructures uphill from the western abutment, for which additional auxiliary supports were necessary. On the north side, in the direction of Dammmühle and Perne , there is a transparent noise protection wall.

Tännichtbachtal bridge

The third and westernmost large engineering structure is the Tännichtbachtal bridge. It is 190 meters long, a maximum of 21 meters high and is divided into five fields. The span of the fields at the edge is 35, that of the three other fields in the middle 40 meters each. The bridge over the Tännichtbachtal is located in the direction of Dresden immediately behind the Nossen triangle, which is why it contains five lanes there, but only three lanes in the opposite direction. The northern superstructure is therefore only 18.75 meters wide, while the southern one is 26.25 meters wide. There is a three-meter-wide space between the two superstructures to allow enough light to penetrate the valley floor with the low clearance height of around 19 meters. During the bridge construction work there were concreting errors, which is why an 80 meter long section of the superstructure had to be demolished and rebuilt. As a result, work on the structure was delayed, but the completion date for the entire route in December 1999 could be met.

Renaturation of the old route

After the traffic on the Chemnitz – Dresden carriageway was relocated to the bridge at the end of February 1999 and the old motorway route at and in the Tanneberger Loch was closed, it began to be completely dismantled over a length of around 5.3 kilometers. The concrete recovered from the roadway was reused in the new road structure after its preparation. Original plans to keep a lane of the old motorway through the Krebsgrund between Dammmühle and the road to Rothschönberg so that trucks can bypass the even steeper ascent of the road in Alttanneberg in winter have been dropped. Instead, the road from Blankenstein to Schmiedewalde was expanded into a district road and a more efficient north-south connection. The traffic control system set up in 1995 was dismantled and rebuilt a little further east on the Brabschützer Berg, the gradient of the A 4 from the Elbe valley between the Dresden-Altstadt junction and the Dresden-West motorway triangle ( federal motorway 17 ).

In addition to the concrete, the entire substructure and, at the end of 1999, the bridge of the connecting road from Tanneberg to Groitzsch that crossed the motorway in Tanneberger Loch disappeared and was replaced by a dam. A terrain modeling was carried out for 2.5 million euros. In order to green the areas, topsoil was filled in, dry grass was sown and a total of 70,000 trees and bushes were planted. In the course of the renaturation measures , the Triebisch was completely exposed. The old route can still be seen, as on the one hand there are no larger trees on it, but on the other hand the trees on the edge have been preserved as well as the old dam. Today there is only a small path in sections and there are also two reservoirs for surface water. The planting of an additional 25 hectares compensated for the encroachment on the landscape caused by the new building.

You can experience nature on the old route for hikers and cyclists via a well-signposted network of trails. A testimony to the old Reichsautobahn architecture in Tanneberger Loch is the bank wall made of concrete faced with granite stones at the weir of the dam mill. It is located directly below the former second (middle) Triebisch Bridge ("Bauwerk 35") and was rebuilt in connection with its construction when the Mühlgraben was given a new course. The wall was damaged in the flood in 2002 and was not repaired afterwards (as of 2020).

literature

  • Robert von Brunn (editor): Bridge structures in the new federal states . Ed .: DEGES . Ernst & Sohn, Berlin 2004, ISBN 978-3-433-01700-5 , pp. 83-88 .
  • Horst Kinkel: The motorway bridge over the Triebischtal . In: Concrete and reinforced concrete construction . Wilhelm Ernst and John Wiley, 2000, ISSN  0005-9900 .
  • Manfred Ranft: The "Tanneberger Loch". In: Announcements of the Landesverein Sächsischer Heimatschutz 3/2000, pp. 42–46.

Web links

Commons : Tanneberger Loch  - collection of images, videos and audio files

Individual evidence

  1. ↑ autobahn-online.de ; Retrieved December 30, 2009.
  2. ↑ a b c d e f g h Manfred Ranft: The "Tanneberger Loch". In: Announcements of the Landesverein Sächsischer Heimatschutz 3/2000, pp. 42–46.
  3. ^ Federal Highway Research Institute: Traffic volume 2010 at the automatic permanent counting point Rothschönberg ; accessed on February 6, 2019.
  4. ↑ a b c d e f g h Federal Ministry of Transport, Building and Housing; Saxon State Ministry for Economy and Labor; DEGES, Deutsche Einheit Fernstraßenplanungs- und -bau GmbH (Ed.): Extension and new construction of the A4 between AK Chemnitz and AD Dresden-Nord. Documentation on the occasion of the traffic opening in November 2003. Potsdam 2003, pp. 39–41.
  5. ↑ a b c d Press release from the Saxon State Ministry for Economic Affairs and Labor  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ; Retrieved December 30, 2009.@1@ 2Template: Toter Link / www.medienservice.sachsen.de  
  6. ↑ a b DEGES (ed.): Bridge structures in the new federal states. Verlag Ernst & Sohn, Berlin 2004, p. 88.
  7. ↑ a b Bernd Moschke: Relief for 66,000 vehicles a day on the A4 near Nossen . In: Dresdner Latest News , edition of January 13, 1999, p. 16.
  8. ↑ Federal Highway Research Institute: 2017 traffic volume at the Rothschönberg automatic counting station ; accessed on February 6, 2019.
  9. ↑ a b Udo Lemke: Tanneberger hole swallowed. In: saechsische.de , June 10, 2003; accessed on January 8, 2020.
  10. ↑ DEGES (ed.): Bridge structures in the new federal states. Verlag Ernst & Sohn, Berlin 2004, p. 84.
  11. ↑ a b Excursion report from 1995, Professorship for Solid Bridge Construction, Faculty of Civil Engineering, TU Dresden (PDF) ( Memento of the original from March 20, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ; Retrieved December 30, 2009. @1@ 2Template: Webachiv / IABot / www.tu-dresden.de
  12. ↑ Federal Institute for Building, Urban and Spatial Research  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ; Retrieved December 30, 2009.@1@ 2Template: Toter Link / www.bbr.bund.de  
  13. ↑ Press release from the Saxon State Ministry for Economic Affairs and Labor  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ; Retrieved December 30, 2009.@1@ 2Template: Toter Link / www.medienservice.sachsen.de  
  14. ↑ Pink touch: It is so green. From accident blackspot to biotope. In: diesachsen.de , December 30, 2016; accessed on January 8, 2020.
  15. ↑ Thomas Haubold: BAB A4: Talbbrücke over the Freiberger Mulde near Siebenlehn / Sa. (Building 45). Arbeitsgemeinschaft Autobahngeschichte e. V., 2012; accessed on January 8, 2020.

Coordinates: 51 ° 3 ′ 26 ″  N , 13 ° 25 ′ 10 ″  E