§ 11. No proposition of expenditure of money for the acquisition of
any real property, or interest therein or the purchase of machinery or
equipment, or the work of construction of terminals, involving an
expenditure of one thousand dollars or upwards, shall be adopted without
the consent of three members of such commission. All construction work
and the purchase of machinery which would involve an expenditure of more
than one thousand dollars shall be upon contract, let after
advertisement and competitive bidding, and on plans and specifications
on file in the office of the commission.