After a drop in billing activity in August, architects were busy at the boards in September, with a monthly index of billings for work that should be launched in the next nine months to a year advancing to positive territory with a reading of 53.7. Any measure above 50 represents an increase in activity on the American Institute of Architects Billings Index (ABI). So far this year, the index has been above 50 in nine months. A separate measure of new projects dropped to 61 from 61.8 in August. “The ABI is back on track after a slight dip in August. The Midwest sector continues to remain strong and in good shape,” Jessica Reinert, executive director of the Iowa chapter of the American Institute of Architects, said in a release. “The challenges now are shifting to supply issues for the industry, including volatility in building materials costs, a lack of a deep enough talent pool to keep up with demand, as well as a lack of contractors to execute design work.”