Mystery Bridge Nr. 86: Brick Culverts spanning Drainage Canals and Gullies along the North Sea

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Culverts- tunnels that channel water under roads. Culverts are used as a substitute for (mainly small to medium-sized) bridges spanning creeks and small waterways as they have several advantages. First and foremost, they provide minimum maintenance, as either earth and roadway cover them or the short crossings are anchored to the ground and supported by abutments. It acts as a canal for directing water under the roadway but also as a dam to keep debris from blocking the roadway. Yet the drawbacks to culverts is that they are not really effective against high water for floodwaters can undermine culverts by washing out the roadways approaching them. In some cases, they can even collapse, swallowing cars in the process, if they attempt to cross them. If they are not washed out by flooding, the high water can cause flooding upstream up until the crossing itself. In summary, engineers should really think about the advantages and disadvantages of culverts before they even implement them as replacements for bridges deemed obsolete.

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This mystery bridge deals with a culvert (or should I say a series of culverts) but in order to better understand the logic behind this, we need to look back at the types of culverts that exist and the oldest known culvert known to human kind.  There are five different types of culverts that are used today: pipe, box, pipe arch, arch and bridge slab- the first three can be multiple spans, the last two are single spans of up to 30 meters. All of them are usually built of steel, stone or concrete. Only a handful have been built using brick.

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Arkadiko Bridge in Greece. Photo taken in 2012 Flausa123 courtesy of wikipedia

 

The oldest known culverts that exist in the world go very far back- way back to the Bronze Age. There, you can find Arkadiko Bridge in the state of Argolis in Greece. Built between 1300 and 1190 BC, the stone culvert has a total span of 22 meters and an arch span of 2.5 meters. It is one of four remaining bridges of its kind using an Mycenaean arch design, all of them are located near Arkadiko.

The next one in line is a stone arch bridge over the River Meles in Izmir in Turkey. Built in 850 BC, this bridge is the oldest of its kind still in use. In Australia, the Macquarie Bridge, featuring a double-barrel arch culvert, is considered the oldest bridge still in use. The 1816 bridge can be found in the Royal Botanical Gardens in Sydney. The Old Enon Stone Arch Culvert, built by Samuel Taylor in 1871 and spans Mud Run in Ohio, is the oldest known culvert in the US and one that was built using limestone.

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The culverts in the Eiderstedt region in the German state of Schleswig-Holstein may not be as old as the aforementioned bridges, nor is it definitely the oldest in Germany- that honor goes to the Stone Arch Bridge (built in 1146 AD) over the River Danube in Regensburg (Bavaria). But given their appearance, they are one of the oldest in the region, let alone in Schleswig-Holstein. The culverts discovered during my tour along the North Sea to Westerheversand Lighthouse consists of box culverts, built using brick as material. They each span a drainage canal which is used to divert water away from the fields during high tides (German: Flut). And despite the bike trail careening along the dikes that are lined along the shores of the North Sea, these culverts are still in use for farm vehicles. The concept is odd, but because farming is practiced in the Eiderstedt region, brick culverts were used along with concrete and sometimes wooden bridges to haul farm vehicles.

 

The dikes were established in the early 1960s, in response to a massive storm that flooded large parts of western Schleswig-Holstein, Lower Saxony and the City of Hamburg in 1962. 400 people lost their lives in Hamburg alone, as dike failures took them by surprise and almost all of the hanseatic city was under water. With the dikes came the rechanneling of waterways, eliminating natural gullies, as one can see while traveling along the North Sea coast. The damming of the rivers, such as the Eider, Au, Sorge and Treene, caused the massive extinction of marine wildlife, including the sturgeon, which used to lay eggs upstream close to the rivers’ starting point. The last sturgeon was caught in 1969 and there has not been a single sturgeon in the region ever since. The creation of the Eidersperrwerk near St. Peter-Ording put the last nails in the coffin of the natural cycle of the North Sea, protecting farmers and residents from the flooding processes.

 

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Detailed markings of one of the culverts. Look at the rust and moss that has developed over the years.

 

Yet the culverts seen in the pics are much older than the dike and drainage systems that have existed since the 1960s. Judging by the green and yellow moss on the brick and the decoloration of the brick and concrete, it is estimated that the culverts are at least a century old, if not older. Unfortunately, there are no records of the date of construction of the culverts, let alone the bridge builder(s) responsible for building them. Not even the German bridge website Brueckenweb.de has any data on the bridges, nor the Dusseldorf-based Structurae.net. Only a map where the author found the structures and the pictures are the only piece of information that is known to exist.

 

While some records may be available through local authorities in Husum, St. Peter-Ording or Eiderstedt, the chances of finding concrete information is very slim, because the culverts are only 20 meters long with a center span of only 5 meters, and there are dozens of them that are known to exist, aside from the ones that were found near Westerhever.

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Do you know of some information on the history of these ancient culverts? Let alone the number of culverts that still exist in the region alone? If so, then please contact the Chronicles and share some information about them. Any clues, including photos, will be of great help. The culverts will be included in the book project on the bridges in Schleswig-Holstein. Information on how you can contribute can be found here. (Hinweis auf Deutsch: Sie können die Information in der deutschen Sprachen übersenden, da der Autor sehr gutes deutsche Kenntnisse hat.)

 

The culverts and the covered bridge profiled here, are a couple of many bridges the author found during his trip to the Eiderstedt region. However, there are plenty more that visitors should see while vacationing there. The author has a few bridges that one should see while visiting the Eiderstedt region. The tour guide will come very soon.

 

Author’s notes:  Enclosed is a map with the exact location and specifics of the culverts found during the trip. Information on the Great Flood of 1962 in Hamburg/ Schleswig-Holstein can be found here. A video on the event can be found here.

Ironically, an even bigger flood occurred 16 years later after the dikes and dams were built. It all occurred during the year summer never existed which ended with the Great Blizzard of 1978/79 that crippled the northern half of Germany, stranding thousands of motorists and causing massive flooding in Schleswig-Holstein alone. More information can be found here. and here.

 

 

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Mystery Bridge Nr. 85: A Covered Bridge with a Thatched Roof

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Thatching is a different but efficient concept for roofing a house. Houses with thatched roofs have a Roof that is built using dry vegetation, such as straw, sedge, heather, water reed, palm fronds and/or rushes and with that, each side of the house has a roof that slants downwards towards the outer edge. Thatched Roofs have a dual function where it allows water to flow off the outer roof, keeping the inner roof dry (and thus preventing rotting and molding of the wood), but at the same time, it acts as an insulator, keeping the warm air inside during the winter and outside during the summer months. Houses with thatches roofs can be found in Areas with tropical climates, but also those with a continental climate, such as the northern parts Germany, Belgium, the Netherlands, France and Great Britain.

While architects find creative ways to building houses with thatched roofs, it is also no surprise that one can find covered bridges with thatched roofs. One just has to stumble across something like this one, located just south of St. Peter-Ording in the German state of Schleswig-Holstein.

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Located on a trail that separates the clinic and the Westküsten Park and Robbarium, this bridge Looks like a typical small crossing that spans a canal that transfers water from the North Sea to the fields to prevent flooding during high tides and severe storms but also to provide water to the farm lands nearby. The bridge is only seven to eight meters long, but the width is about 40 centimeters wider, especially if you count the overhead portion.  In bridge terminology, the bridge is a through truss using the Kingpost design. The entire structure is made of wood.

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Close-up of the A-framed Kingpost truss design.

Yet looking at it further, it definitely has the thatched roof appearance, as two different layers are added to the roof to make it unusual. The top layer has either sedge or rush roofing, whereas the bottom layer has the typical reed roofing, one sees with houses in Schleswig-Holstein and neighboring Mecklenburg-Pommerania. This type of construction makes the bridge very unusual for a covered bridge, but it does lead to the question of whether this is the only bridge of ist kind in the region, Germany or even Europe, or if there are similar bridges of ist kind out there. and if so, where.

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Close-up of the thatched roofing: The reed is the bottom layer; the sedge or rush is the top layer.

While the roof has the function of protecting the remaining elements from rotting or molding caused by moisture from rains, the structure itself is no older than 20 years old, for even though there is moss on some of the wooden beams, the bridge and its trusses look relatively new. Therefore, it is estimated that the bridge was built between 1995 and 2005, if not later. It is the question of who built it and why the engineer decided for this unique design.

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If you know more about this bridge, please send the author an e-mail with some information about it. This will be useful for the upcoming book project on the bridges of Schleswig-Holstein. What is just as important (or even more) than this bridge is the following:

How many covered bridges have a thatched roof similar to this one? And where are they located?

 

A discussion Forum has been established on facebook, Twitter, LinkedIn and Instagram so that you can comment on this. Photos and info for the other bridges would be much appreciated.  🙂

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