Modular Concrete Otter Bridge for Waterway Crossings
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Solution Overview
Problem
Existing solutions for small animal bridges, such as drying tubes, brick bank berms, fascine bank edge strips, wooden pole bridges, and gabions, face issues like high installation costs, aversion by animals, narrowing of culvert cross-sections, rotting materials, and difficulty in installation due to limited space, which hinder effective ecological rehabilitation of watercourses.
Innovation Solution
A prefabricated concrete small animal bridge system with adjustable length, using hooked and sliding concrete elements, integrated into the embankment with angle parts, offering a stable, durable, and non-narrowing passage with open sides for visibility and easy installation, capable of accommodating varying water levels and widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If drying tubes or tunnels are used, then passage is provided for animals, but installation costs increase and animals may be averse to the passage
Solution Approach 1:
The bridge is divided into multiple modular elements (side parts, running surfaces, connecting parts) that can be assembled in sections. This segmentation allows for easier transportation and installation while maintaining the functionality of providing animal passage without requiring expensive large-scale tunnel construction.
Solution Approach 2:
The invention transitions from underground passages (tunnels) to an above-water bridge structure. This dimensional change provides animal passage while avoiding the high costs and animal aversion associated with enclosed tunnels, as animals can see and access the passage more naturally.
2Ease of operation
If brick bank berms or gabions are used, then passage is provided for animals, but the discharge cross-section is narrowed
Solution Approach 1:
The bridge structure is designed to be adaptable to different water levels and flow conditions. The modular elements can be configured to maintain adequate discharge cross-section while providing animal passage, allowing the structure to dynamically respond to varying hydraulic conditions without permanently narrowing the channel.
Solution Approach 2:
Instead of building berms that narrow the channel horizontally, the invention elevates the passage above the water level. This vertical dimensioning allows animal passage without reducing the horizontal discharge cross-section of the culvert.
3Ease of operation
If wooden pole bridges or fascine bank edge strips are used, then passage is provided for animals, but the materials rot over time
Solution Approach 1:
The bridge combines concrete elements (side parts, running surfaces) with natural materials strategically. The concrete components provide long-lasting structural support and resistance to rot, while natural materials are used only where they serve specific functional purposes and can be replaced if needed.
Solution Approach 2:
The design accepts that some natural materials may degrade over time, but structures them in a way that allows for easy replacement of individual elements without replacing the entire bridge. The critical structural components are made of durable concrete, while less critical natural elements can be maintained or replaced as needed.
4Ease of operation
If gabions or brick berms are used, then passage is provided for animals, but the bridge piers become invisible for damage detection
Solution Approach 1:
The bridge is designed as a modular structure with distinct separable elements. This segmentation allows inspection personnel to access and examine individual components, including bridge piers and connecting parts, without the obstruction caused by solid berms or gabions.
Solution Approach 2:
By positioning the animal passage above the water level and using open-sided modular elements, the design maintains clear visibility of bridge support structures. This elevated, open configuration allows unobstructed inspection of piers and foundations for damage detection.
5Ease of operation
If wooden piles are rammed for wooden pole bridges, then passage is provided for animals, but the bridge foundation may be impaired
Solution Approach 1:
The bridge uses concrete elements as the primary structural component, replacing the need for wooden piles. Concrete can be cast into place or installed as pre-fabricated elements without requiring aggressive pile driving that could damage the bridge foundation.
Solution Approach 2:
The design uses modular concrete elements that can be installed with minimal foundation work. Instead of requiring deep wooden piles driven into the ground, the concrete modules can rest on prepared surfaces or use minimal anchoring, reducing the risk of foundation impairment.
Data Source
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AI summary
The small animal bridge, consisting of precast concrete elements that can be connected in series, differs from known otter crossing structures primarily in that it neither rots nor significantly restricts the flow cross-section of the watercourse under a road bridge. It can even be integrated into low or narrow culverts. The open design ensures visibility of the bridge piers and unimpeded water flow. The invention is designed for mass production and can be used or retrofitted to all common bridges that cross rivers and lack natural bank structures in this area. A special variant, featuring a permeable, covered (21) geosubstrate-filled lower level (20), further supports invertebrate migration.The bridge elements consist of a walking surface (13) with slightly raised lateral edges (14), on which geogenic and biogenic material increases the likelihood of animals using the bridge. The side sections (15) are stabilized by transverse (16), longitudinal (18), or diagonal connections. The concrete elements are joined by interlocking, sliding (22), or connecting pieces (19) (with a visible opening for receiving a connecting piece (17)).