Stone Bridge Regensburg
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Stone Bridge Regensburg

Site Information

Country: Germany
State: Regensburg, Bavaria
Location: 49° 1' 17" N - 12° 5' 48" E
Field Documentation Date(s): May 1st, 2008
Project 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
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Photo-textured 3D point cloud of Stone Bridge Regensburg

Site Description

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Spanning across the northern and southern arms of the mighty Danube River, the Stone Bridge is one of the most prominent landmarks in the city of Regensburg along with the Regensburg Cathedral. The Stone Bridge remained the river’s only crossing for more than 800 years, acting as a vital traffic artery between the great centers of Ulm and Vienna, as well as central junction between northern France and much of the rest of Europe. As the oldest stone bridge in Germany to remain relatively unchanged, the continual preservation of this masterpiece of medieval architecture is of the utmost importance.

In 2007, the Stone Bridge was nominated for the award "Historic Landmark of Structural Engineering" in Germany. It is a Romanesque arch bridge, built of natural stone and lime mortar. It has 15 arches visible today (each spanning about 10 to 17m), 14 pillars (6-8m wide each), and spans a total length of around 315m. Originally, the bridge was heavily fortified for defense as well as durability and possessed three defensive towers, out of which only the bridge tower on the southern side has been preserved.

The bridge has undergone severe erosion over the years. By early 2005, a series of cracks between the facade and arch 12 had widened considerably, in certain cases extending beyond the front wall and into the carrying arch construction. By June 2005, a structure of braced steel beams was built to support the bridge and prevent the existing cracks from expanding. This was one of the impetuses for banning all vehicular traffic on the bridge except for foot traffic.
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History

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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. It connected the imperial and Bavarian parts of Regensburg. During its construction, royal patronage transferred from the Duke of Bavaria to the emperors of Germany; King Konrad III was the most notable of these patrons and greatly influenced the completion of the Stone Bridge. 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. In 1245, the Free Imperial City of Regensburg was registered as the owner of the bridge.

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, 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 pillar on the southern side were completely covered with more recent constructions when the municipal salt storehouse was built between 1616 and 1620. Additionally, there was a small harbour at the base of Am Wiedfang street in the bridge's early centuries that is now covered by later constructions.

The Stone Bridge's pillar foundation was constructed within a cofferdam made of oak planks. The bridge pillars were constructed with stone and lime mortar cores rather than wooden posts. They rest on a large oak beam-grate that was built atop the gravel bed of the Danube River, at the bottom of the cofferdam. For the purpose of protection against undercutting from the current, the pillars are surrounded by arrow-shaped structures 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 the 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 of Bavaria and the Free Imperial City of Regensburg. Located at the bridge's highest point is the "Bruckmandl" (mannequin of the bridge) statue, which symbolizes municipal rights, liberties and the region's Protestant emancipation from 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 protected in the Regensburg’s Historical Museum.
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Perspective of the historic Stone Bridge and Salzstadl, created from photo-textured laser scan data

Project Narrative

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The laser scanning of the Stone Bridge took place in May 2008. The survey team of Christofori und Partner started scanning 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 dataset. With this dataset, detailed plans of the Stone Bridge were created for the restoration purposes. Also, the team of Christofori und Partner created a 3D Model for future structural calculations.
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Photo-textured 3D point cloud of pillar 5 and arches 5 and 6 along the Stone Bridge

Preservation

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Due to heavy strain on the bridge in recent decades, the durability of the bridge has strongly eroded from overuse and is no longer fit for traffic. The bridge has been 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 demonstrating that the bridge railing would not withstand a bus collision. Additionally, high water levels, acid rain and heavy rainfall have infiltrated the bridge and severely damaged the mortar of the walls through the accumulation of salts, dirt, and lime. 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

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Credits:

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CyArk
     - John Mink
            Lead Researcher

     - Jörg Bierwagen
            Dipl.-Ing. (TU) Architekt

     - Erwin Christofori
            Dipl.-Ing. (FH) Beratender Ingenieur

     - Jörg Gräfensteiner
            Dipl.-Ing. (FH) Vermessung

     - Dirk Haeusleigner
            Dipl. Ing. (FH) Vermessung und Geoinformatik

     - Helmut Heinisch
     - Rainer Stoecklein