or settlement for work performed by the Contractor under these Specifications and Contract, and as a condition precedent to the liability of the Board for any amount other than contained in the estimates approved by the Engineer, any question at issue *767 involving the amount or rate of settlement or liability of the State for an amount other than as shown by the estimates approved by the Engineer, shall be referred to a board of arbitration for decisions and award. Said board of arbitration shall consist of three persons, one to be chosen by the State Highway Board, one by the Contractor, and the third by these two. The board of arbitration shall make such rules as it shall determine equitable to govern itself in the conduct ofthe investigation and determination of the award. In determining the award, the majority of the board of arbitration shall govern, and the parties to the Contract shall be bound by the findings of said board of arbitration, certified copies of which findings and award shall be filed with the State Highway Board and Contractor. The board of arbitration shall fix the amount of the cost of the proceedings, including a fair and reasonable compensation to the arbitration board members and shall determine how the total cost shall be borne. The authority of the board of arbitration shall not extend to the interpretation of the Plans and Specifications, or the determination of the qualities of the materials or workmanship furnished by the Contractor. The board of arbitration shall have