The commissioner may, at any time, call for bids to construct, alter, reconstruct, improve, relocate, widen or change the grade of sections of state highways or bridges. All bids shall be submitted on forms provided by the commissioner and shall comply with the rules and regulations provided in the bid specifications. The commissioner shall state the amount of the bond which shall accompany each bid and shall name the place where bids shall be received and the time and place for opening the same. Each bid shall be accompanied by a surety company bond satisfactory to the commissioner and in such sum as the commissioner determines, and shall be so conditioned that, if the contract is awarded to the bidder, such bidder shall, when required by the commissioner, execute an agreement in writing, to be prepared by said commissioner, with such bond as shall be acceptable to the commissioner, conditioned as provided in § 49-41. The commissioner may reject any and all bids if, in the commissioner’s opinion, cause exists therefor; but otherwise the commissioner shall award the contract to the lowest bidder deemed to be responsible. The successful bidder shall give evidence satisfactory to said commissioner of such bidder’s ability to perform the contract. When such contract is executed by the commissioner and the successful bidder, a copy of the contract, with an estimate of the cost of the work, shall be immediately filed with the commissioner.