In addition to others contained in 23 U.S.C. 101(a), the following definitions shall apply as used in this regulation:

Applicant. The State highway agency is the applicant for Federal assistance under 23 U.S.C. 125 for State highways and local roads and streets which are a part of the Federal-aid highways.

Betterments. Added protective features, such as rebuilding of roadways at a higher elevation or the lengthening of bridges, or changes which modify the function or character of a highway facility from what existed prior to the disaster or catastrophic failure, such as additional lanes or added access control.

Catastrophic failure. The sudden failure of a major element or segment of the highway system due to an external cause. The failure must not be primarily attributable to gradual and progressive deterioration or lack of proper maintenance. The closure of a facility because of imminent danger of collapse is not in itself a sudden failure.

Emergency repairs. Those repairs including temporary traffic operations undertaken during or immediately following the disaster occurrence for the purpose of:

Minimizing the extent of the damage,

Protecting remaining facilities, or

Restoring essential traffic.

External cause. An outside force or phenomenon which is separate from the damaged element and not primarily the result of existing conditions.

Heavy maintenance. Work usually done by highway agencies in repairing damage normally expected from seasonal and occasionally unusual natural conditions or occurrences. It includes work at a site required as a direct result of a disaster which can reasonably be accommodated by a State or local road authority's maintenance, emergency or contingency program.

Natural disaster. A sudden and unusual natural occurrence, including but not limited to intense rainfall, floods, hurricanes, tornadoes, tidal waves, landslides, volcanoes or earthquakes which cause serious damage.

Proclamation. A declaration of emergency by the Governor of the affected State.

Serious damage. Heavy, major or unusual damage to a highway which severely impairs the safety or usefulness of the highway or results in road closure. Serious damage must be beyond the scope of heavy maintenance.

State. Any one of the United States, the District of Columbia, Puerto Rico or the Virgin Islands, Guam, American Samoa or Commonwealth of the Northern Mariana Islands.