Lowell Greimann, professor emeritus at Iowa State University and an expert in bridge engineering, was a guest Friday afternoon on a segment of National Public Radio's "Talk of the Nation-Science Friday."

In an interview with host Ira Flato, Greimann discussed the collapse of the Interstate 35W bridge over the Mississippi River at Minneapolis, and fielded questions from callers all over the nation.

The segment is downloadable free of charge on the NPR/Talk of the Nation Web site, and may be heard on MP3 players or computers equipped with the proper software.

For more, visit Talk of the Nation-Science Friday

Go to the bottom of the page to click on the segment marked "Minneapolis bridge collapse."