Yarn bomb

A volunteer works at attaching some of the 580 blanket-sized, hand-knitted panels to the pedestrian walkway of the Andy Warhol bridge in downtown Pittsburgh, Aug. 11, 2013.

More than 1,800 knitters covered the bridge in 3,000 feet of colorful yarn, in what organizers claim is the nation's largest yarn bomb.

Pedestrians walk across the Andy Warhol bridge in downtown Pittsburgh, Aug. 12, 2013.

Allegheny County workers attach knitted blankets to a portion of the Andy Warhol bridge, Aug. 11, 2013.

Volunteers attach some of the 580 blanket-sized panels to the pedestrian walkway of the Andy Warhol bridge, Aug. 11, 2013.

A volunteer attaches some of the 580 blanket-sized panels to the pedestrian walkway of the Andy Warhol bridge, Aug. 11, 2013.

A riverboat passes under the Andy Warhol bridge in downtown Pittsburgh, Aug. 11, 2013.

Volunteers attach some of the 580 blanket-sized, panels to the pedestrian walkway of the Andy Warhol bridge, Aug. 11, 2013.

Volunteers admire some of the 580 panels they helped attach to the pedestrian walkway of the Andy Warhol, Aug. 11, 2013.

The Andy Warhol bridge is seen covered in more than 3,000 feet of colorful, knitted yarn, Aug. 12, 2013.

Volunteers attach some of the 580 blanket-size panels to the pedestrian walkway of the Andy Warhol bridge, Aug. 11, 2013.

A volunteer attaches a knitted panel to the pedestrian walkway of the Andy Warhol bridge, Aug. 11, 2013.