Section 170.456 - How can a Tribe request an exception from the design standards?(a) A Tribe can request an exception from the required design standards from FHWA. The engineer of record (the State licensed civil engineer whose name and professional stamp appear on the PS& E or who is responsible for the overall project design) must submit written documentation with appropriate supporting data, sketches, details, and justification based on engineering analysis.(b) FHWA can approve a project design that does not conform to the minimum criteria only after giving due consideration to all project conditions, such as:(1) Maximum service and safety benefits for the dollar invested;(2) Compatibility with adjacent features; and(3) Probable time before reconstruction of the project due to changed conditions or transportation demands.(c) FHWA has 30 days from receiving the request to approve or decline the exception.