§ 170.456When can a tribe request an exception from the design standards?
A tribe can request an exception from the design standards in Appendix B of this subpart under the conditions in this section. The tribe must submit its request for a design exception to the BIA Regional Office for approval. If the BIA Regional Office has design exception approval authority within their IRR Stewardship Plan with FHWA, they may approve or decline the request; otherwise BIA forwards the request to FHWA. The engineer of record must submit written documentation with appropriate supporting data, sketches, details, and justification based on engineering analysis.