If the governing body of any county concludes to adopt a contract system for working, maintaining and operating the several sections of highways, roads, bridges and ferries in its county, or any part thereof, the county supervisor or governing body, as soon as practicable thereafter, may advertise in a newspaper published in the county once a week for three weeks and by notices posted in two or more conspicuous places in the several townships or the township to be worked by the contract system for bids from responsible persons for the performance of the work as above set forth, and may furnish specifications of all such work or contracts as have been advertised.