Text 6: George P. Coleman Bridge

Brief information:

Location: Yorktown, Virginia, USA

Completion Date: 1952 (original), 1995 (reconstruction)

Cost: $9 million (original), $76.8 million (reconstruction)

Length: 3,750 feet

Type: Movable (double swing span)

Purpose: Highway

Materials: Steel, concrete

Longest Single Span: 500 feet

Engineer(s): Parsons Brinckerhoff, Inc.

In the spring of 1995, the largest double-swing-span bridge in the United States was dismantled and replaced in only nine days. The George P. Coleman Bridge in Virginia was originally constructed in 1952 as a two-lane highway designed to carry no more than 15,000 vehicles a day. By 1995, the population around the bridge had increased so much that the structure was carrying in excess of 27,000 vehicles a day.

To make matters worse, the machinery that rotated the massive swing spans often experienced mechanical problems. In short, the bridge was a major headache. Engineers considered several designs to ease congestion -- from building a tunnel to constructing a new bridge upstream -- but the least expensive option proved to be reconstruction of the existing bridge. So between May 4 and May 13, 1995, about 2,500 feet of truss and swing spans -- complete with pavement, lightpoles, and barrier walls -- were floated in six sections over 40 miles from Norfolk, Virginia, to the bridge site. It marked the first time in engineering history that such an enormous bridge was assembled off site and floated into place.

The new four-lane bridge is three times wider than the original bridge and can now carry up to 50,000 vehicles daily.

Fast Facts:

· The George P. Coleman Bridge is the largest double-swing-span bridge in the United States and the second largest in the world.

· The new bridge weighs only 25 percent more than the original because the new spans are made of lightweight, high-strength steel.

· The two main river piers contain mechanisms that lift the swing spans to different elevations so they don’t hit each other when they rotate.