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THE FUNNEL CONCEPT For bridge protection from meandering streams or rivers. THIS METHOD IS A DAVE DERRICK DISCOVERY (DDD).
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THE FUNNEL CONCEPT For bridge protection from meandering streams or rivers
THE FUNNEL CONCEPT: Extending both existing bridge abutments using vegetated keys or other bank protection methods angled away from the stream until the upstream opening of the funnel is wider than the measured or calculated meander belt width of the stream.
A simple concept where the stream planform might not have to be modified to obtain satisfactory bridge flow alignment and/or bridge protection.
Meander Belt (width): (1) The part of a flood plain encompassed between two lines tangent to the outer bends of all the meanders. (2) The zone within which channel migration has historically occurred. Within the meander belt, channel migration is indicated by abandoned channels, accretion topography (scrolling), and oxbow lakes. From the International Erosion Control Association’s glossary of terms
THE FUNNEL CONCEPT – DON’T TOUCH THE STREAM, BUT MAKE SURE THE STREAM GOES THROUGH THE HOLE IN THE BRIDGE Present stream alignment Future stream alignment Extension of the bridge abutment Extension of the bridge abutment BRIDGE OPENING
If a stream is wildly meandering upstream of a bridge, then the stream is trying to increase roughness & length, & decrease slope to achieve dynamic equilibrium. Straightening the stream decreases roughness & length, & increases slope, which gives the stream more power, usually with disastrous results (more meandering, headcutting, etc.)
THE FUNNEL CONCEPT – Can be accomplished by using keys or bank protection methods to extend the abutments of the bridge until the upstream opening of the funnel is wider than the meander belt width of the stream system!! Present stream alignment xxx Future stream alignment BRIDGE OPENING
Live Siltation or pole plantings Present stream alignment Backfilled & seeded Stone Future stream alignment Launchable vegged buried key FUNNEL THEORY BRIDGE OPENING
Cattaraugus Creek Upstream of the Rt. 16 Bridge Arcade, NY NYS-DOT Designer: Lallman Ramboli
If ever there was a project in need of a funnel, this is it! The stream is getting behind both upstream bridge abutments (arrows) ((double crazy!!!!)) Rt. 16
Looking upstream. A few years ago the stream was flowing along the red line. Now bank erosion & stream migration has resulted in severe misalignment with the 4 lane Rt. 16 Highway bridge, Sardinia, NY
Always look at high flow stream attack angles Flow bypassing bridge opening Direct attack into roadway
Put the Funnel to it! Exactly what Lallman Ramboli with NYS-DOT did, proposed plan of stone bank protection & Rock Vanes shown over aerial of existing conditions Proposed realigned flow
Lallman’s funnel 1 year later Flow well aligned using LPSTP, Rock Vanes, an ERR, & vegetation
3 years later. From the Rt. 16 bridge looking upstream @ the LPSTP-Rock Vane funnel guiding flow into the bridge opening
THIS NEEDS A FUNNEL TOO I was riding along in Western New York, I have no idea what the name of this stream is!
Looking US from another bridge @ flanking of stone bank protection. Funnel protection would have been more effective & cheaper here!
This PowerPoint presentation was developed & built by Dave Derrick. Any questions or comments, call my personal cell @ 601-218-7717, or email @ d_derrick@r2d-eng.comEnjoy the information!!
Let’s crank it up & build something else!! Kaylyn Louise May, age 2