When the district has received unanimous approval from the boards of supervisors of the counties comprising the district pursuant to Section 29156 of this code, or when the board has made its order pursuant to Section 29157.1 of this code, the board shall call a special election and submit to the qualified voters of the district the proposition of incurring such bonded indebtedness for the acquisition, construction or completion of rapid transit facilities by the district and all other works, property, or structures necessary or convenient therefor and for the purpose of carrying out the provisions of this part.