By the filing as provided in § 13a-240 of a determination authorizing a series of bonds for a purpose described in said determination in accordance with said § 13a-240, the principal amount of said bonds shall be deemed to have been appropriated for said purpose, and the Commissioner of Transportation may proceed in the name and on behalf of the state, on an authorization or appropriation basis, subject to approval by the Governor of allotment thereof, to award contracts and incur obligations with respect to such purpose in amounts not in the aggregate exceeding the authorized principal amount of said bonds, notwithstanding that such contracts and obligations may at any particular date exceed the amount of the proceeds of such bonds theretofore received by the state.