They found the total parking area to be larger than 1,000 football fields, or covering more than two square miles. Bryan Pijanowski, an Associate Professor of Forestry and Natural Resources at the university, who led the study in the county of Tippecanoe, said the finding surprised him.
Pijanowski counted 355,000 parking spaces in Tippecanoe County, home to about 155,000 residents. Farmers could produce 250,000 bushels of corn in the same space taken up by county parking lots, he said. "I can't help but wonder: Do we need this much parking space?"
Pijanowski said that his results are cause for concern, in part, because parking lots present environmental and economic problems. They are, for instance, a major source of water pollution, he said.
Tippecanoe County parking lots turn out about 1,000 pounds of heavy metal runoff annually, said Purdue professor Bernard Engel, who used a computer model to estimate changes in water-borne runoff caused by land-use changes.
Engel, head of the Department of Agricultural and Biological Engineering, said lots are troublesome because pollutants collect on their non-absorbent surfaces and are then easily carried away by rain. "Rain then flushes these contaminants into rivers and lakes," he added.
Parking lots also help add to the "urban heat island effect," which can raise local temperatures 2 to 3 degrees Celsius, according to Indiana climatologist Dev Niyogi.
"Urban areas have a higher capacity to absorb radiation from the sun than surrounding areas, and these areas become warmer," Niyogi said. Pijanowski said his study has relevance outside of Tippecanoe County because his findings typify a troubling trend he's observed.
Generally, Americans pave an increasing percentage of land each year for their cars and trucks. Pijanowski called for businesses to be more creative about utilizing combined-use or shared parking lots, thereby saving construction and property costs while minimizing land use.
A different approach to development planning could mitigate the monetary and environmental costs associated with parking areas, he said. Pijanowski conducted his survey using digitalized aerial images of Tippecanoe County taken in 2005, which he then analyzed to count the number of total parking spaces and the land area they consume.
He presented the results of his work in May at a conference of land-use experts in the Netherlands. This survey is the first in a series aimed at assessing the automobile's impact on land-use patterns, Pijanowski said.