AG-64R4-S-13-0017AY_Construction_of_Low_Water_Crossing_-_Sign_Layout.pdf

low-water stream crossings C10.1

As an alternative to replacing deficient structures on low- traffic roads, low-water stream crossings (LWSC) are sometimes selected as a cost-effective alternative. When this option is used, proper regulatory and warning signs should be installed.

Flood Area Ahead Sign. The Flood Area Ahead sign is a diamond-shaped warning sign and is yellow with black lettering and border.

The standard size is 30 inches by 30 inches.

This sign would usually be installed about 750 feet in advance of the low-water crossing or at the last turnaround location for vehicles, which-ever is greater. If the location of the low-water crossing is not readily visible from approxi-mately 1,000 feet, use of a supplemental distance advisory plate mounted below the Flood Area Ahead sign may be considered. An advisory speed plate may also be considered if the recom-mended crossing speed is less than the speed limit established by law or regulation for the approach roadway. If an advisory distance plate is used with the Flood Area Ahead sign, a speed advisory plate can be mounted under the next sign, Impassable During High Water. Neither supplemental plate should be used alone.

Do Not Enter When Flooded Sign. The Do Not Enter When Flooded sign consists of a 24-inch by 30-inch rectangular sign with black lettering and border on a white background.

Since this is a regulatory sign, installation and enforcement requires an appropriate resolution by the board of supervisors or city council. This sign should be installed about 200 feet from the actual low-water crossing.

Low-Water Stream Crossings

30" x 30"

Impassable During High Water Sign. The Impassable During High Water sign is diamond-shaped and yellow with black lettering and border. The standard size is 30 inches by 30 inches. This sign is normally installed about 450 feet in advance of the low-water crossing.

30" x 30"

24" x 30"

In addition to these recommended signs, the following suggestions should be considered in establishing low-water crossings:

• Use only on low-volume, unpaved roads.

• Do not use on roads that serve occupied dwellings where no alternate emergency access is available.

• Perform timely maintenance of signs and roadway, particularly after flooding.

Additional information can be obtained from the Iowa DOT Office of Local Systems.

low-water stream crossings C10.2

Typical signing of low water stream crossing (LWSC)

The following illustration shows a suggested typical layout for signing of a low water crossing in Iowa.