DE102006047679B4 - Small animal bridge for flowing water traffic route crossings - Google Patents

Abstract

Small animal bridge for flowing water - traffic route - crossings consisting of assembled or lined-up individual elements, characterized - that the individual elements are purpose-specific prefabricated rot-proof parts - that the elements each have a running surface and two side parts - that the small animal bridge from straight direction and if necessary -curved or angled elements,- that the angle parts for integration into the slope or for changes of direction within the passage can be both end and intermediate parts,- that the elements can be hooked or pushed into one another by the end faces or the use of Connecting parts are connected to each other - that a few standardized sizes - height, width - are sufficient to construct the appropriate small animal bridge for each passage concerned.

Description

1. Topic

Flowing water - traffic route - crossings are retrofitted or equipped with small animal bridges if the culverts below the road bridges have no berms or natural or near-natural bank structures. Accordingly, they are used in the context of the ecological rehabilitation of running waters, i. H. in hydraulic engineering.

2. State of the art

1. a) Trockenröhren, -tunnel
2. b) gemauerte Uferbermen
3. c) Uferrandstreifen aus Faschinen mit Holzpfählen und Steinhinterfüllung
4. d) Holzpfahlstege und
5. e) Steingefüllte Gabionen (sog. Drahtsteinkörbe bzw. Drahtschotterkörbe).

Known technical variants to allow semi-aquatic small animals or mammals the passage below roads / traffic routes in spatial connection with watercourses are:

1. a) Drying tubes, tunnels
2. b) brick bank berms
3. c) Shore strips made of fascines with wooden stakes and stone backfill
4. d) wooden pier walkways and
5. e) Stone-filled gabions (so-called wire stone baskets or wire gravel baskets).

1. a) Trockenröhren bzw. -tunnel werden insbesondere neben gefluteten Rohrlässen, Dükern, Wehren - also bei sehr beengten Platzverhältnissen - angeordnet. Sie sind nicht immer gut für die Tiere auffindbar und weisen keine natürlichen Strukturen, d. h. Bewuchs, auf. Fehlende Fluchtmöglichkeiten, insbesondere bei langen Tunneln, wie sie sich für breite Straßen oder bei Autobahnen ergeben, führen zu Aversionen der Tiere gegenüber dieser Passage. Zudem sind sehr große Durchmesser der Röhren bei entsprechender Länge nötig, um von den Ottern etc. angenommen zu werden. Das wiederum ist mit hohen Investitionskosten verbunden. Allgemein ist für den Einbau solcher Röhren ein hoher Arbeitsaufwand nötig.
2. b) Gemauerte Uferbermen setzen einen ausreichend großen Fließquerschnitt voraus, da sie diesen einengen. Der Wasserrückstau vor der Verkehrsbrücke nimmt zu. Diese Variante kann nur eingesetzt werden, wenn der Hochwasserabfluss trotz der entstehenden Verengung gesichert ist. Für den Bau muss der Arbeitsraum gegen Wasser abgeschirmt werden, so dass eine zeitweilige Umleitung des Gewässers oder eine aufwändige bauliche Konstruktion nötig wird, die Bermen zu erstellen. (Anderfalls ist eine Unterwasserbetonierung möglich - aber ebenfalls kosten- und arbeitsaufwändig.) Uferbermen versperren in jedem Fall den Blick auf den unteren Anteil des Brückenpfeilers bzw. -fußes.
3. c) Uferrandstreifen, die aus Faschinen und Holzpfählen mit Steinhinterfüllung hergestellt werden, verringern ebenfalls den Abflussquerschnitt und sind damit für enge Durchlässe ungeeignet. Für das Rammen der Holzpfähle ist eine gewisse Mindesthöhe des Durchlasses notwendig, der jedoch oft nicht gegeben ist. Zudem kann das Rammen selbst zu Beeinträchtigungen am Fundament der Brücke führen. Uferrandstreifen ermöglichen ebenfalls keine freie Sicht auf die unteren Anteile der Brückenkonstruktion. Und Holz wie Faschinen unterliegen der Verrottung.
4. d) Holzpfahlstege engen den Durchflussquerschnitt nicht ein, sie ermöglichen auch die Sicht auf die Brückenpfeiler und sie sind eine einfache und relativ kostengünstige Lösung. Ihre Konstruktion setzt aber, wie bereits vorhergehend beschrieben, eine Mindesthöhe zum Rammen der Pfähle voraus, und das Rammen selbst ist auch für die Brücke nicht immer vollkommen gefahrlos. Von deutlichem Nachteil ist weiterhin das Verrotten des Steges.
5. e) Bei Gabionen handelt es sich um mit Steinen oder Schotter gefüllte Drahtkörbe, deren Oberfläche zur besseren Passage mit Holzbrettern bzw. -bohlen belegt wird. Sie aufzustellen ist mit kostenintensiver Handarbeit verbunden. Wie bei allen Varianten, die den Abflussquerschnitt einengen, ist auch hier keine Sicht auf die Brückenpfeiler hinter den Gabionen möglich, um Schäden am Brückenbauwerk frühzeitig festzustellen. Für schmale Durchlässe ist diese Variante ungeeignet. Hinzu kommt, dass die Holzanteile verrotten und die Drahtkörbe verrosten.

All variants were mentioned by Ms. Heike Neumann in her thesis on the subject: Preventive measures in otter protection with special consideration of the traffic situation (University of Rostock, Faculty of Agricultural Sciences, Department of Regional Culture and Environmental Protection, 1997).

1. a) Drying pipes or tunnels are arranged in particular next to flooded pipe passages, culverts, weirs - i.e. where space is very limited. They are not always easy for the animals to find and do not have any natural structures, ie overgrowth. A lack of escape opportunities, especially in long tunnels, such as those found on wide roads or on motorways, lead to the animals being averse to this passage. In addition, very large diameters of the tubes with a corresponding length are necessary in order to be accepted by the otters etc. This in turn is associated with high investment costs. In general, a lot of work is required for the installation of such tubes.
2. b) Brick bank berms require a sufficiently large flow cross-section, as they constrict it. The backwater in front of the traffic bridge is increasing. This variant can only be used if the flood discharge is secured despite the resulting narrowing. For the construction, the work area must be shielded against water, so that a temporary diversion of the water body or a complex structural design is necessary to create the berms. (Otherwise, an underwater concreting is possible - but also expensive and laborious.) Bank berms always block the view of the lower part of the bridge pier or base.
3. c) Riparian strips made of fascines and wooden piles with stone backfill also reduce the discharge cross-section and are therefore unsuitable for narrow culverts. A certain minimum clearance height is required for driving the wooden posts, but this is often not the case. In addition, the ramming itself can lead to impairments in the foundation of the bridge. Bank edge strips also do not allow a clear view of the lower parts of the bridge construction. And wood, like fascines, is subject to rot.
4. d) Wooden pier walkways do not restrict the flow area, they also allow a view of the bridge piers and they are a simple and relatively inexpensive solution. However, as already described above, their construction presupposes a minimum height for ramming the piles, and the ramming itself is not always completely safe for the bridge either. Another significant disadvantage is the rotting of the bridge.
5. e) Gabions are wire baskets filled with stones or gravel, the surface of which is covered with wooden boards or planks for better passage. Setting them up involves costly manual work. As with all variants that narrow the discharge cross-section, it is also not possible to see the bridge piers behind the gabions here in order to detect damage to the bridge structure at an early stage. This variant is unsuitable for narrow openings. In addition, the wood parts rot and the wire baskets rust.

3. Problem

Biotopes are known to be cut up by roads, motorways and railway lines. These biotopes also include streams and rivers. In these areas, semi-aquatic small animals such as B. otters (also: muskrat, brown-chested hedgehog, badger, Elbe beaver, fox, black rat, stoat, weasel, mink, stone marten, polecat, brown rat, water shrew, etc.) increasingly to overcome the roads, which often leads to the death of the animals.

Investigations have shown that, among other things, the often tightly dimensioned river culverts in the past, which have no natural bank structures in the bridge area, lead to aversions of the animals, so that the culverts, although theoretically possible, cannot be swum through. And animals that live on rivers but are not swimmers themselves also seek the way across the road because there are no banks.

The small animal bridge, also known in the literature as the otter passage, is part of a complex of measures intended to enable the animals to make their way through the bridge passage, since the need for protection has been proven for otters, they are considered to be particularly sensitive and show pronounced migratory behavior. As already described, there are different ways to build a small animal bridge to choose from. However, all known options are problematic. Either they further narrow the already narrow culverts (often just as wide as the river bed width) so that the design flood flow is no longer secured [brick bank berms, bank edge strips made of fascines and stone filling, gabions]; or they can only be realized with great effort [dry pipes, tunnels, underwater masonry or temporary river diversion]; they rot over time [wood, fascines, gabion baskets] or they cannot be installed at the site in question because the installation height [ramming height for wooden piles] is not given. In addition, drying tubes z. B. also not be accepted accordingly, since they do not offer the animals any possibility of escape during the passage.

4. Solution including benefits achieved

A solution was sought for a bridge construction for small animals that combines the advantages of the previous variants while minimizing the disadvantages. In addition, a search was made for a solution that could be used as universally as possible. And this was found with the Small Animal Bridge (also called Otter Passage), which is described below.

The small animal bridge consists of prefabricated concrete parts that can be lined up or put together, which are hooked together on the front sides (top edge), pushed together by sliding the elements on the front sides (grooves (22)) or by using connecting parts (19) (reinforced concrete, concrete, steel, iron or similar). . Ä. / e.g. U-pieces) can be connected and thus result in otter paths of any length (running length). The integration into the embankment or in the case of a change of direction takes place via angle parts, which can be end members or intermediate pieces.

The concrete parts can be manufactured in various standard sizes. The dimensioning of the height of the concrete parts depends on the average, summer and winter annual mean water level, the width results from the necessary walkway width for Otter passages of at least 0.5 m and a possible additional width due to special design features of the respective culvert (e.g. narrowing of the culvert above the waterline).

The prefabricated parts are made of concrete, washed aggregate, reinforced concrete or aerated concrete. The general wall thickness depends on the size of the prefabricated parts, but is normally approx. 5 cm, with larger versions and elements made of reinforced concrete correspondingly more.
The edges are slightly rounded to minimize the resistance of the draining water.
The surface of the small animal bridge forms a closed running surface (13) with slightly raised side edges (14) so that stones that are used for marking (scent marking), dead wood, gravel, etc. can be stored on it without immediately rolling down.

The sides (15) should be as open as possible. This ensures free visibility and control of the foot of the road bridge and free swim-through for the ichthyofauna. In addition, manufacturing and transport costs (concrete weight) are thereby minimized, and the parts can be placed inside each other during transport.

The stability of the side parts is achieved by transverse (16), longitudinal (18) or diagonal connections.

A variant with a basement (20) was also developed, which supports the migration of aquatic invertebrates. This is discussed in more detail in the further embodiment of the invention.

Other advantages of the construction

• • Langlebigkeit / Haltbarkeit - im Vergleich zur Verrottung von Holzstegen oder der Durchrostung der Gabionenkörbe
• • Stabilität - da Beton so massiv ist, dass selbst Hochwasserabflüsse diese Konstruktion nicht einfach mitreißen können; es werden auch keine Vibrationen durch den Straßenverkehr auf die Lauffläche übertragen, die sonst zu Aversionen der Tiere führen könnten
• • keine wesentliche Querschnittseinengung beim Durchfluss und nur minimaler Aufstau - im Gegensatz zu Gabionen oder gemauerten Bermen, dadurch auch bei beengten Platzverhältnissen einsetzbar
• • das Aufstellen der Teile ist bei normalem Abfluss (und jahreszeitlich relativ unabhängig) möglich - im Gegensatz zu Bermen, welche gemauert werden müssen (und u. U. sogar einer Umleitung des Flusses bedürfen)
• • der Aufbau ist auch bei geringer Brückenhöhe möglich - im Gegensatz zu Holzstegen oder Uferrandstreifen mit Faschinen, deren Pfähle gerammt werden müssen
• • der Aufbau erfolgt ohne Gefahr oder Beeinträchtigung der Straßenbrücke - im Gegensatz zu Pfahlrammarbeiten
• • Handarbeit bei der Aufstellung ist gering - im Gegensatz zu Gabionen - und der Aufwand vertretbar
• • die Otterpassage muss nicht an der Brücke befestigt werden
• • die Konstruktion gewährt den vollen Einblick auf den Brückenfuß zu Kontrollzwecken - im Gegensatz zu Gabionen, gemauerten Bermen oder massiv gestalteten Uferrandstreifen
• • bei Bedarf (z. B. Brückenreparatur) ist die Konstruktion wieder entfernbar, ohne dass sie dadurch zerstört werden würde - im Gegensatz zu allen anderen bekannten Varianten
• • die Betonteile lassen sich in die Böschung problemlos einbauen und gegebenenfalls verankern
• • wenige Größen, d. h. zwei Breiten und etwa drei Höhen reichen aus, um für jeden betroffenen Straßendurchlass die passende Kleintierbrücke konstruieren zu können
• • für die Bemessung reichen i. d. R. die Mittelwasserstände (Jahresmittel- und Winterwasserstand), die sich oft bereits an den Brückenpfeilern abzeichnen, die Durchlasshöhe und -breite aus
• • aufwendige Planungen und Berechnungen, wie sie für durchlasseinengende Varianten (Faschinenuferrandstreifen, gemauerte Bermen, Gabionen) nötig sind, werden hier minimiert
• • durch eine Serien- bzw. Massenproduktion wird eine günstige Preisgestaltung möglich
• • die Otterpassage aus Betonfertigteilen ist, wie beschrieben, eine massive Konstruktion - dennoch wiegt sie im Vergleich zu steingefüllten Gabionen der gleichen Größe mit Untergeschoss (leer) nur etwa die Hälfte, ohne diese Spezialausführung sogar noch weniger und
• • im Notfall trägt sie auch Menschen oder größere Tiere (als Otter).

consist in:

• • Longevity / durability - compared to the rotting of wooden walkways or the rusting through of gabion baskets
• • Stability - as concrete is so massive that even flood drains cannot easily sweep this structure away; no vibrations from traffic are transmitted to the walking surface, which could otherwise lead to aversions of the animals
• • No significant narrowing of the cross-section in the flow and only minimal accumulation - in contrast to gabions or brick berms, which means that it can also be used in confined spaces
• • the parts can be erected with normal flow (and relatively independent of the season) - in contrast to berms, which have to be bricked (and may even require the river to be diverted)
• • The construction is also possible with a low bridge height - in contrast to wooden footbridges or embankment strips with fascines whose piles have to be rammed
• • The construction takes place without danger or disturbance of the road bridge - in contrast to piling work
• • There is little manual work involved in setting up - in contrast to gabions - and the effort is justifiable
• • the Otterpassage does not have to be attached to the bridge
• • The construction allows a full view of the foot of the bridge for control purposes - in contrast to gabions, brick berms or massively designed riparian strips
• • If necessary (e.g. bridge repairs), the construction can be removed again without being destroyed - in contrast to all other known variants
• • the concrete parts can be built into the embankment without any problems and anchored if necessary
• • just a few sizes, ie two widths and around three heights, are sufficient to be able to construct the right small animal bridge for each street passage concerned
• • The mean water levels (annual mean and winter water level), which are often already visible on the bridge piers, are usually sufficient for the dimensioning, as well as the passage height and width
• • Elaborate planning and calculations, such as those required for passage-restricting variants (fascine bank shoulders, bricked-up berms, gabions), are minimized here
• • favorable pricing is possible through serial or mass production
• • the otter passage made of precast concrete elements is, as described, a massive construction - yet compared to stone-filled gabions of the same size with a basement (empty), it weighs only about half, without this special version even less and
• • in an emergency, it also carries people or larger animals (than otters).

Further development of the invention

A special variant of the small animal bridge is the Otterpassage, which contains a basement (20). This is filled with gravel, sand, dead wood and also larger stones. The resulting gaps serve as hiking trails for the invertebrates; the phytoplankton and zooplankton that settle there serve them as food. This variant is particularly suitable where there is a sufficient cross-section in the culvert and the bridge culvert is otherwise secured with concrete grid panels (12) or massive rock fill, so that the migration of the invertebrates is restricted.

Towards the top, the described layer is covered with a geogrid, which is permeable to invertebrates but holds gravel, or heavily perforated concrete, so that the gravel etc. is kept underground during flood water runoff. The side walls can also be made permeable for invertebrates, i. H. be perforated or slotted. The invertebrate migratory layer is filled with the installation of the concrete parts on site.

character list

• 1 : Arrangement of a small animal bridge under a road bridge - top view, variant with angle elements
• 2 : Arrangement of the small animal bridge under a road bridge - cross-section on the left - an otter passage with a basement for invertebrate migration on the right - an otter passage (variant with cross-connections)
• 3 : Individual element of the small animal bridge - variant with closed basement* (for invertebrate migration), illustration without filling of the invertebrate tunnel (* the basement was shown without holes or slits for the sake of clarity)
• 4 : Individual element of the small animal bridge - variant with cross-connections
• 5 : Individual element of the small animal bridge - variant with longitudinal connections

Reference List

1

small animal bridge

2

running water (river, stream)

3

embankment (belonging to the river)

4

traffic route (road, highway)

5

traffic bridge (road bridge)

6

Marker stones (to mark the animals by scent)

7

trees and shrubs

8th

Small animal bridge with filled basement

9

Small animal bridge - with stabilizing cross-connections of the side parts

10

mean water level in the summer months

11

mean water level in the winter months

12

fortified water bed z. B. Concrete grid panels

13

tread

14

raised side edge

15

side panel

16

stabilizing cross connection of the side parts

17

Opening for receiving a connecting part

18

stabilizing longitudinal connection of the side parts

19

connecting part (U-piece)

20

basement

21

ceiling of the basement

22

Groove for sliding two bridge elements into each other

Claims (10)

Small animal bridge for flowing water - traffic route - crossings consisting of assembled or lined-up individual elements, characterized - that the individual elements are purpose-specific prefabricated rot-proof parts - that the elements each have a running surface and two side parts - that the small animal bridge from straight and if necessary -bent or angled elements, - that the angle parts for integration into the slope or in the case of changes of direction within the culvert can be both end and intermediate parts, - that the elements can be hooked or pushed into one another by the end faces or the use of Connecting parts are connected to each other - that a few standardized sizes - height, width - are sufficient to construct the right small animal bridge for each passage concerned. small animal bridge after claim 1 , characterized in that the elements are made of a concrete material, ie concrete, reinforced concrete, aggregate concrete or aerated concrete. small animal bridge after claim 1 , characterized in that the elements are made of a combination of different concrete materials. Small animal bridge after one of Claims 1 until 3 , characterized in that all edges pointing towards the water are rounded. Small animal bridge after one of Claims 1 until 4 , characterized in that - that the running surface - upper side of the elements - has slight elevations on the lateral edges, and - that geological substrates such as gravel, sand, stones and biogenic material such as wood, branches, pieces of bark, moss are applied to the running surface in a variable mixing ratio are. Small animal bridge after one of Claims 1 until 5 , characterized in that the side parts are largely open so that the bridge piers are accessible at all times for visual inspection. Small animal bridge after one of Claims 1 until 6 , characterized in that the side parts are stabilized by transverse, longitudinal, diagonal connections or a combination of these different connections. Small animal bridge after one of Claims 1 until 7 , characterized in that - that the small animal bridge is equipped with a fillable basement - that the filling of geological and biogenic material - gravel, pebbles, stones, wood, pieces of bark, etc. - consists, and - that the basement has sides made of concrete, the are heavily perforated or slit so that aquatic invertebrates or aquatic insects can pass through them. small animal bridge after claim 8 , characterized in that - the basement is open at the top and, after filling, is covered by a wide-meshed or coarse geogrid, which is permeable to aquatic invertebrates or aquatic insects, and - that the geogrid is attached to the side panels. small animal bridge after claim 8 , characterized in that - that a cover of the basement consists of concrete, which has many small holes or slits, and - that the cover is thus permeable for aquatic invertebrates or aquatic insects.

Images