(a) Before any county shall be eligible to receive the benefits of the provisions of this subchapter, the county, through its county judge, shall agree to comply with the terms, provisions, and limitations of this subchapter.
(b) When any county shall have met the requirements of this subchapter and shall have become eligible for state aid, the state aid engineer, as soon as practicable, shall notify such county in writing of such eligibility and that its proportionate part of any state funds allocated to the county for state aid may be utilized for construction on the state aid system in the manner provided in this subchapter.