7-14-2531. Definition of term single purpose. (1) It shall be deemed a single purpose to:

(a) acquire a right-of-way for and construct a public highway, including any bridge or bridges thereon;

(b) contribute to the cost of a federal-aid bridge;

(c) contribute to the cost of a federal-aid highway project on a highway leading to a federal-aid bridge.

(2) Construction of two or more bridges not forming a part of the same public highway shall be deemed separate purposes.