A floodway is a flood plain crossing for a road, built at or close to the natural ground level.[1] It is similar to a causeway, but crosses a shallow depression that is subject to flooding, rather than a waterway or tidal water.[2]

A floodway on a gravel road

They are designed to be submerged under water, but withstand such conditions. Typically floodways are used when the flood frequency or time span is minimal, traffic volumes are low, and the cost of a bridge is uneconomic[2][3] – in most cases, in rural areas.


Floodway on Great Northern Highway, Western Australia
Floodway and signs, eastern side of Southern Cross, Western Australia
Floodway (road goes across the photo) in Baja California, Mexico. Note bridge behind it.

See also

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Notes

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  1. ^ a b MRWA Waterways Section; BG&E Pty Ltd (24 April 2006). "Floodway Design Guide" (PDF). Main Roads Western Australia. p. 4. Archived from the original (PDF) on 15 April 2015. Retrieved 15 April 2015. "Archived copy" (PDF). Archived from the original (PDF) on 15 April 2015. Retrieved 22 April 2015.{{cite web}}: CS1 maint: archived copy as title (link)
  2. ^ Austroads; Flavell, David; Audora, Henry (1994), Waterway design : a guide to the hydraulic design of bridges, culverts and floodways, Austroads, ISBN 978-0-85588-440-6
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