Use of public transportation in many communities is dropping by almost 50 percent when temperatures rise to uncomfortable levels, according to a recent study co-authored by researchers at University of Texas at Austin and University of Washington, as well as Ram Pendyala, director of the School of Sustainable Engineering and the Built Environment, part of the Fulton Schools, and faculty members in the school Steven Polzin, Mikhail Chester, Irfan Batur and Victor Alhassan. The article looks at the recent impacts of heat on ridership in 11 major cities and details the steep declines in use of buses and rail transit uses when heat rises to extreme levels. Officials are exploring solutions, but riders say they are experiencing increasing frustration.