The secretary of transportation, before awarding any contract for the construction, improvement, reconstruction or maintenance of the state highway system, shall publish notice of the letting at least once in each week for two consecutive weeks in the Kansas register, which notice shall specify with reasonable minuteness the character of the improvement contemplated, the time and place at which the bids will be received, and invite sealed proposals for the same. Such other notice may also be given as such secretary may deem necessary and proper.