In the event of great emergency, including, but not limited to, states of disaster defined in Section 8558 of the Government Code, upon the majority vote of the board, the board may proceed at once to replace or repair any and all bridges without adopting plans, specifications, strain sheets, or working details and without letting contracts or calling for bids. The work may be done by day labor under the direction of the board or by contract, or by a combination of the two. If done wholly or in part by contract, the contractor shall be paid the actual cost of the use of machinery and tools and of material and labor expended by him or her in doing the work, plus not more than 15 percent to cover all profits, supervision, and any other expense. No more than the lowest current market prices shall be paid for materials.