Philadelphia’s vast tracts of vacant land and abandoned buildings – about 40,000 properties by one count – are costing the city, and taxpayers, a fortune. A new study (pdf) by Econsult and two partners found that the blighted properties were depressing the city’s property values by billions of dollars, while directly costing city agencies $20 million a year. We’ll talk to Econsult’s RICHARD VOITH, lead author of the report done on behalf of the Philadelphia Redevelopment Authority and the Philadelphia Association of Community Development Corps. We’ll also talk to JOHN KROMER of the University of Pennsylvania’s Fels Institute of Government, who recently prepared a report (pdf) updating the status of vacant properties in Eastern North Philly that he first inventoried as the city’s Office of Housing and Community Development in 1998. Those properties redeveloped by the Asociación de Puertorriqueños en Marcha represent a rare success story.