§ 153.078 RAILROAD, HIGHWAY, STREET STREAM CROSSINGS.

   In addition to the requirements of § 153.076:

   (A)   Crossings are designed to offer minimal obstructions to the flood flow;

   (B)   Where failure or interruption of public transportation facilities would result in danger to public health or safety, and where practicable, and in consideration of FHWA Federal-Aid Policy Guide, 23 C.F.R. part 650A:

      (1)   Bridge lower chords shall have freeboard to at least two feet above the base flood elevation to help pass ice flows, the base flood discharge, and any debris associated with the discharge; and

      (2)   Culverts shall be designed to pass the base flood discharge and maintain at least two feet freeboard on the crossing surface;

   (C)   Normal overflow channels, if possible, are preserved to allow passage of sediments to prevent aggradations; and

   (D)   Mid-stream supports for bridges, if necessary, have footings buried below the maximum scour depth.

(Prior Code, § 11-2(9.4))

Statutory reference:

   Railroad, highway, and street stream crossing regulations in the floodway, see ARM § 36.15.602(2)