The powers of the district created pursuant to this chapter shall be exercised by a commission. The commission shall consist of two members of the governing body of each locality in the district, appointed by the respective local governing body. In addition to the appointed members, the Chairman of the Commonwealth Transportation Board or his designee shall be a member of the commission of the district created pursuant to this chapter. The commission shall elect a chairman from its membership. The chairman may be the chairman or presiding officer of a local governing body. In addition, the commission, with the advice of the district advisory board, shall elect a secretary and a treasurer, who may be members or employees of any local governing body or other governmental body. The offices of secretary and treasurer may be combined. A majority of the commission members shall constitute a quorum, and a majority vote shall be necessary for any action taken by the commission. No vacancy in the membership of the commission shall impair the right of a majority of the members to form a quorum or to exercise all of its rights, powers, and duties.