All facilities, buildings and structures constructed by the authority shall be constructed according to plans and specifications of architects or engineers selected by the authority. Such construction shall be done under the supervision and direction of the Alabama Building Commission or any agency designated by the Legislature as its successor following award for each part of the work to the lowest responsible bidder after advertising for receipt and public opening of sealed bids; provided, that the invitations for bids and the bidding documents shall be so arranged that any alternates from the base bid shall constitute cumulative deductions from the base bid; and, in determining the lowest bidder, if funds are insufficient to construct the facilities, buildings and structures on the lowest base bid, then the commission may proceed to consider the bids upon the basis of the base bids of all bidders minus the respective reductions stated for the first alternate and, if the lowest bid so determined is not then within the funds available, the commission shall proceed to consider the base bid minus the first and second alternates together to determine the lowest bid and in like manner throughout all alternates, if need be, so that in no event shall there be any discretion as to which alternate or alternates will be used in determining the lowest responsible bidder. All such contracts shall be lump sum contracts. All contracts for the entire work shall be awarded at the same time, but notice to proceed may be withheld until prior work under another contract has progressed to a point where the joint or following work can best be coordinated for the earliest completion of the entire project in a sound and workmanlike manner. The contracts shall be executed by the authority upon the determination of the commission as to the lowest bidders, respectively.

Payments made by the authority under the construction contracts shall be upon the contractor's written sworn request only if endorsed as approved by the commission or in any lesser amount the commission shall endorse as having been the earned on said contract.

The authority and the commission shall agree to a construction cost estimate including reimbursement to the commission of its reasonable direct cost in having plans, specifications and contract documents prepared and in supervising and inspecting the work. After the contracts have been awarded, such construction cost estimates shall be revised, and all extras on the contracts may be awarded within the funds available.