Did the Adena Giant Mound Builders Construct a Bridge Over the  Ohio River?

At the Portsmouth, Ohio mound and sacred via complex, the parallel walls extend to the Ohio River and continue on the other bank.  This would imply that a bridge continued the sacred via across the river?  The following account given by the Iroquois Indians about the giants being bridge builders may confirm a little talked about a hypothesis.

Iroquois Legend
   In Iroquois hydrography, Ohio—the great river of the ancient Alligewi (Adena) domain—is the central stream to which all the rivers of the mighty West converge. This stream the emigrants now attempted to cross. They found, according to the native annalist, a rude bridge in a huge grape-vine which trailed its length across the stream. Over this, a part of the company passed, and then, unfortunately, the vine broke. The residue, unable to cross, remained on the hither side, and became afterward the enemies of those who had passed over. Cusick anticipates that his story of the grape-vine may seem to some incredible; but he asks, with amusing simplicity, "why more so than that the Israelites should cross the Red Sea on dry land?" That the precise incident, thus frankly admitted to be of a miraculous character, really took place, we are not required to believe. But that emigrants of the Huron-Iroquois stock penetrated southward along the Allegheny range, and that some of them remained near the river of that name, is an undoubted fact. Those who thus remained were known by various names, mostly derived from one root—Andastes, Andastogues, Conestogas, and the like—and bore a somewhat memorable part in Iroquois and Pennsylvanian history. Those who continued their course beyond the river found no place sufficiently inviting to arrest their march until they arrived at the fertile vales which spread, intersected by many lucid streams, between the Roanoke and the Neuse rivers. Here they fixed their abode and became the ancestors of the powerful Tuscarora nation. In the early part of the eighteenth century, just before its disastrous war with the colonies, this nation, according to the Carolina surveyor, Lawson, numbered fifteen towns, and could set in the field a force of twelve hundred warriors.