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.
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:
Maximum service and safety benefits for the dollar invested;
Compatibility with adjacent features; and
Probable time before reconstruction of the project due to changed conditions or transportation demands.
FHWA has 30 days from receiving the request to approve or decline the exception.