By September 1st of each even-numbered year prior to a funding period, each eligible county shall submit a final prospectus for each project for which it seeks RATA funds. Each final prospectus shall be submitted on forms provided by the county road administration board and shall include a vicinity map, a typical cross-section (existing and proposed), and, if a design deviation is required, an evaluation and determination by the county engineer. If a project is for the improvement of a road which continues into an adjacent county and the project terminus is within 1,000 feet of the county line, the prospectus shall include a statement signed by the county engineer of the adjacent county certifying that the adjacent county will cooperate with the applicant county to the extent necessary to achieve a mutually acceptable design. All final prospectuses shall indicate that the design of the project shall begin not later than one year from the date of project approval by the county road administration board, and that construction of the project shall begin not later than six years from the date of project approval by the county road administration board. All final prospectuses shall come from the pool of preliminary prospectuses submitted and field reviewed as specified in WAC 136-161-030 and 136-161-040. All counties shall use current cost pricing to estimate project costs. Inflation and contingency rates will be applied by the county road administration board based upon project type.