23 CFR § 661.53
What standards should be used for bridge design?
May 21, 2020
(a) Replacement—A replacement structure must meet the current geometric, construction and structural standards required for the types and volumes of projected traffic on the facility over its design life consistent with 25 CFR part 170, Subpart D, Appendix B and 23 CFR part 625.
(b) Rehabilitation—Bridges to be rehabilitated, as a minimum, should conform to the standards of 23 CFR part 625, Design Standards for Federal-aid Highways, for the class of highway on which the bridge is a part.