---
kind: "section"
citation: "23 C.F.R. § 650.117"
title: "23"
number: "650.117"
heading: "Content of design studies."
url: "https://uscodex.org/cfr/23/650.117"
---

# §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)](/cfr/23/650.115.md?p=a), and
  - (3) For proposed direct Federal highway actions, the reasons, when applicable, why FEMA criteria ([44 CFR 60.3](/cfr/44/60.3.md), formerly [24 CFR 1910.3](/cfr/24/1910.3.md)) 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)](/cfr/23/650.115.md?p=a-1-ii), and
  - (2) **The magnitude and water surface elevation of the base flood, if larger than the overtopping flood.**

## Notes

### Source

Source: 44 FR 67580, Nov. 26, 1979, unless otherwise noted.

### Authority

Authority: 23 U.S.C. 119, 144, and 315.