Chicago is embarking on a $7 billion plan to transform the city’s infrastructure from the skies above to the pipes underground.

Mayor Rahm Emanuel is planning to announce the initiative Thursday. It includes projects to expand the city’s largest airport and improve its streets, water system, schools, community colleges, parks and commuter rail network. The city estimates that these initiatives will create 30,000 jobs over the next three years.

At a time when the nation is only beginning to pull itself painfully and delicately out of a deep recession, and when cities and states are cutting essential services and wondering how to keep the courthouses open and the lights on, an infrastructure proposal for a single city with an estimated cost in the billions — with a “b” — is audacious. Mr. Emanuel, in an interview, suggested that nothing less than this “integrated, comprehensive approach” will do for what he calls “building a new Chicago.”