Stone Bridge Regensburg
History
Project Narrative
Preservation
Area Descriptions
Credits
Stats
Country: GermanyState: Regensburg, Bavaria
Location: 49° 1' 20" N - 12° 5' 49" E
Project Date(s): May 1st, 2008
Release Date(s): June 6th, 2009
Time Range: 1135 CE - 1146 CE
Era: Medieval
Culture: German
Site Authority: Stadt Regensburg
Heritage Listing: UNESCO World Heritage Site
Site Description
Along with the Regensburg Cathedral, the Stone Bridge is the most prominent landmark of the city of Regensburg and is considered a masterpiece of medieval architecture. In 2007 it was nominated for the award "Historic Landmark of Structural Engineering" in Germany. With 15 arches visible today (each spanning about 10 to 17m), 14 pillars (6-8m wide each), and a total length of around 315m, the mighty Stone Bridge stretches over the northern and southern arm of the Danube as well as the two Wöhrd islands.
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History
The Stone Bridge of Regensburg was planned and built in approximately eleven years, from 1136 to 1147. It was largely funded by the merchants of Regensburg, and, as it connected the Imperial part of Regensburg to the Bavarian part, royal patronage transferred during its construction from the Duke of Bavaria to the Emperors of Germany (most notably King Konrad III, who greatly influenced its completion). The merchants, however, had the largest stake in the bridge's completion as it would greatly facilitate the ease of transferring goods and services across the Danube, and this was later reflected in the fact that the Free Imperial City of Regensburg was registered as the owner of the bridge in 1245.
The Stone Bridge was used for crossing the Danube and quickly became a vital traffic artery as the river's only crossing between the great centers of Ulm and Vienna; indeed, for more than 800 years it served as the sole Danube-spanning bridge in Regensburg, the town located at the river's northernmost point and thus a central junction between northern France and much of the rest of Europe. The Stone Bridge was used throughout the Middle Ages by emperors and kings traversing these routes, and was crossed by the crusader army of Louis VII. It served as an inspiration and model for other great stone bridges of the 12th and 13th centuries, including those across the river Elbe in Dresden, the Vltava in Prague (Judith Bridge; the predecessor of today's Charles Bridge), the Thames in London, and the Rhone in Avignon.
The Stone Bridge is a Romanesque arch bridge, built of natural stone and lime mortar and heavily fortified for defense as well as durability. The first arch and the first pillar on the southern side were completely covered with more recent construction when the municipal salt storehouse was built between 1616 and 1620, but they are still preserved in-state under the access-road to the bridge. Additionally, there was a small harbour at the base of Am Wiedfang street in the bridge's early centuries that is covered by later construction.
The Stone Bridge's pillar foundation was constructed within a cofferdam made of oak planks. The bridge pillars, constructed with stone and lime mortar cores rather than wooden posts, rest on a large oak beam-grate that was built atop the gravel bed of the Danube, at the bottom of the cofferdam. For the purpose of protection against undercutting from the current, the pillars are surrounded by arrow-shaped, artificial islands, the so-called pillar islands. The islands considerably narrow the volume of water running through them, resulting in a difference in the water level of about 0.5m between the head water and the water at the bottom of the bridge. This causes a strong current under the bridge arches that whirls below the bridge, producing the well-known "Regensburg Danube Whirlpool".
Originally, the bridge had three defensive towers, out of which only the bridge tower on the southern side has been preserved. The black tower to the north side was destroyed during Napoleon's advance and the middle tower was dismantled in 1784 following a series of damaging collisions with ice. The great archway on the side of the bridge tower, as well as the broadening of the bridge behind it, were built at the beginning of the 20th century during construction of a railway tram. This bridge archway was destroyed by German troops on April 23rd, 1945, in order to slow down the American advance.
The northern end of the bridge used to be the state border between the Duchy (later Electorate) of Bavaria and the free imperial city of Regensburg. Located at the bridge's highest point is the "Bruckmandl" (mannequin of the bridge), which symbolizes municipal rights and liberties and the region's protestant emancipation from the tutelage of the bishop. This figure originally dated to the year 1446, though the current version on the bridge is a replica dating to April 23rd, 1854. The earlier figure is now located in the Historical Museum Regensburg to protect it from the ravages of the elements.
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Project Narrative
The laser scanning of the Stone Bridge took place in May 2008. The survey team of Christofori und Partner started scanning the corpus of the Bridge with a Leica HDS 3000 and a Leica HDS 6000 Scanner. The team scanned the whole bridge with a point distance of 4mm. Additional panoramic photographs were taken and mapped onto the point clouds. In August 2008, all the data was registered together into a complete site facsimile dataset. With this dataset, detailed plans for restoration of the stone bridge were created. Also, the team of Christofori und Partner created a 3D-Model for future structural calculations.
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Preservation
Due to a heavy strain of use on the bridge in recent decades, the durability of the bridge has strongly eroded and it is no longer fit for traffic. The bridge was closed to non-commercial traffic since 1997, and a ban on buses and taxis followed on August 1st, 2008, following the release of a structural report that demonstrated that the bridge railing would not withstand a collision with a bus. Additionally, high water levels, acid rain and normal heavy rainfall have seeped into the bridge and have severely damaged the mortar of the walls through the accumulation of salts, dirt, and lime. These factors have also coupled with the heavy machine traffic across the bridge to create a precarious structural condition. Now that vehicular traffic has been banned from the bridge, additional refurbishment and consolidation work can be planned - aided by the highly accurate results of HD laser documentation.
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Area Descriptions
Credits:
- Jörg Bierwagen
- Erwin Christofori
- Jörg Gräfensteiner
- Dirk Haeusleigner
- Helmut Heinisch
- Rainer Stoecklein
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