CFR > Title 23 - Highways > CHAPTER I—FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION > SUBCHAPTER G—ENGINEERING AND TRAFFIC OPERATIONS (parts 620 to 669) > PART 650—BRIDGES, STRUCTURES, AND HYDRAULICS > SUBPART A—Location and Hydraulic Design of Encroachments on Flood Plains (§650.101 to §650.117) > 650.117—Content of design studies.

650.117—Content of design studies.

(a) The detail of studies shall be commensurate with the risk associated with the encroachment and with other economic, engineering, social or environmental concerns.
(b) Studies by highway agencies shall contain:
(1) The hydrologic and hydraulic data and design computations,
(2) The analysis required by § 650.115(a), and
(3) For proposed direct Federal highway actions, the reasons, when applicable, why FEMA criteria ( 44 CFR 60.3, formerly 24 CFR 1910.3) are demonstrably inappropriate.
(c) For encroachment locations, project plans shall show:
(1) The magnitude, approximate probability of exceedance and, at appropriate locations, the water surface elevations associated with the overtopping flood or the flood of § 650.115(a)(1)(ii), and
(2) The magnitude and water surface elevation of the base flood, if larger than the overtopping flood.