Wondering why development news seems to have ground to a halt? The nation’s housing and economic woes are hitting development firms and slowing the demand for construction. The American Institute of Architects said in a study released today that “commercial construction across the country is experiencing a major downturn.” A leading indicator of the demand for construction work fell to its lowest level since October 2001, leaving an average lag time of almost a year between architectural billings and construction spending. Some firms are paring their workforce; others are bidding on more stable projects such as schools, hospitals and government buildings. Construction costs are falling. What’s next?