Hammer Canal Bridge
The Hammerkanalbrücke is a road bridge in Esslingen am Neckar . It leads the Neckarstrasse over the Hammer Canal. The building erected in 1896 has the status of a technical monument .
History and description
During the founding period , the city of Esslingen was expanded eastwards; from around 1890 the Oststadt was the most important new development area in the city. Since a good connection to the city center and above all to the train station was necessary, the Hammer Canal had to be bridged. For cost and aesthetic reasons it was decided to use a solid concrete bridge . In 1896 the Hammer Canal Bridge, which has a span of around 19 meters and a width of around 14 meters, was built. The arrow height is 1.8 meters, which means that the bridge is very flat. The specification for the arrow height resulted from the requirements of the raft ride on the one hand and the upper edge of the road surface on the other. The course of the canal and the planned adjoining development and the road layout made it necessary to erect the bridge at an angle. It runs at an angle of 58.3 ° to the canal axis.
construction
Portland cement was introduced in Germany around 1880. The Hammer Canal Bridge was a technical novelty in its time. Concrete bridges are now usually provided with steel inserts. The first generation of concrete bridges, to which the Hammerkanal Bridge also belongs, were built without such reinforcement and, moreover, were not cast from concrete, but built using rammed construction. This means that the concrete was mixed with a significantly lower proportion of water during processing and was roughly the consistency of freshly dug earth. It was compacted with rammers until all the air bubbles had escaped and the rammers left almost no marks on the building material. It was worked in layers 15 to 25 centimeters thick. In order to prevent the formation of cracks, which could be promoted by movements of the bridge, concrete bridges were provided with so-called joints even before the Hammer Canal Bridge was built, with fixed pivot points in three joints of the arch. They consisted of steel components, shaped stones or, in the early days, mainly of lead plates. Claus Köpcke was the first master builder to construct such joints in 1880. However, he had the joints poured out with mortar after his bridges had been completed and thus fixed, because they were only intended to compensate for the movements of the bridges during construction. Permanent joints were first used in 1895, the year before the Hammer Canal Bridge was built, on the Danube Bridge in Inzigkofen , which was destroyed in World War II. This bridge had iron pivot joints as rotation points. The Hammer Canal Bridge, a very early example of the use of permanent joints, is, however, provided with lead inlays in the inner third of the joint. City architect Keppler, who was responsible for the design and construction of the bridge, wrote: “The arrangement of the joints enables the greatest material savings, since the vaults are statically determined and can therefore be produced in the smallest dimensions. The dangerous effects of the subsidence occurring during the formwork and the influences of the changing loads and temperatures are avoided at the same time. "
The inclination of the bridge posed a particular challenge when using this already new technology. Keppler had the joints staggered to follow the course of the spur line , which meant that the Hammer Canal Bridge had several axes of rotation that caused secondary stresses in the bridge vault. Keppler considered this problem negligible in view of the small dimensions of the bridge and the adaptability of the lead plates. He also divided the bridge into four isolated, narrow longitudinal strips to minimize the problem.
Optical design
Keppler refrained from concealing concrete as a building material and imitating natural stone, as was still common in his day. He also did not imitate the typical arch shape of a hingeless bridge, the thickness of which increases continuously from the crown to the fighters, but showed the arch shape of the three- hinged arch open. With this type of construction, the strength of the bow both towards the top and towards the fighters decreases, while the legs show a clear thickening - a sight that was still unusual at the time. He also deliberately left the lead joints unhidden. The front surfaces of the bridge were clad with a 5 to 10 centimeter thick layer of particularly fine concrete, the arch was profiled like a bead, and the bridge was also colored. The gussets were painted with a bluish, the bulges with a yellowish amphiboline paint. In addition, there was reddish red sandstone on the cornice panels, pedestals, etc. The wrought iron railings were painted dark and golden bronze. These elements of the design are now hardly recognizable.
Karen Veihelmann, who published a work on the bridge in monument preservation in Baden-Württemberg in 2015 , declared Keppler's Hammer Canal Bridge to be "downright revolutionary" and stated that the bridge is the oldest surviving example of the bridge type described and is largely in its original condition.
literature
Karen Veihelmann, The Hammer Canal Bridge in Esslingen am Neckar. The first generation of three-hinged arches made of stamped concrete , in: Denkmalpflege in Baden-Württemberg 1, 2015, pp. 26–31 ( online )
Web links
- The Hammer Canal Bridge on stuttgartwege.blogspot.de
Individual evidence
- ↑ Quoted from Karen Veihelmann, Die Hammerkanalbrücke in Esslingen am Neckar. The first generation of three-hinged arches made of stamped concrete , in: Denkmalpflege in Baden-Württemberg 1, 2015, pp. 26–31, here p. 29
- ↑ Karen Veihelmann, The Hammer canal bridge in Esslingen. The first generation of three-hinged arches made of stamped concrete , in: Denkmalpflege in Baden-Württemberg 1, 2015, pp. 26–31, here p. 31
| Upstream | Crossing the Neckar | Downstream |
| Water house | Hammer Canal Bridge |
Agnes Bridge |
Coordinates: 48 ° 44 ′ 13.4 " N , 9 ° 18 ′ 39.1" E