The county road engineer shall certify to the board and has authority over all estimates and all bills for labor, materials, provisions, and supplies with respect to county roads, prepare standards of construction of roads and bridges, and perform such other duties as may be required by order of the board.
He or she shall have supervision, under the direction of the board, of establishing, laying out, constructing, altering, improving, repairing, and maintaining all county roads of the county.