The only explanation.
The Arcola Trail Bridge is a “White Lady” haunting. The apparition of a woman, dressed all in white, searches for lost husband near the Arcola Trail Bridge. A number of “White Lady” hauntings are described throughout the United States. Whether these stories represent folklore or actual hauntings that occur as a result of certain tragic events at these locations is hard to say.
There is also a legend concerning a blue light at the Arcola Trail Bridge. Blue lights are another common paranormal event described in a lot of places, including a number of bridges in the United States.
Resources:
The Shadowlord (1998). Shadowlands Haunted Places Index. Retrieved January 30, 2011 from http://theshadowlands.net/…/minnesota.htm
Wikipedia (2011). History of Minneapolis. Retrieved January 30, 2011 from http://en.wikipedia.org/wiki/History_of_Minneapolis
StrangeUSA.com (2005-2009). Arcola Trail Bridge. Retrieved January 30, 2010 from http://www.strangeusa.com/ViewLocation.aspx?locationid=5665