This is Roald Tweet on Rock Island.
The entire length of the Mississippi River is stitched together in ragged zigzags of bridges, creating a crazy quilt out of the bordering states.
No two stitches are the same. Some bridges are suspended high above the water to let boats pass; others hop across the river on piers and swing open for boats. Mississippi bridges are wide or narrow, straight or twisting—as if the engineers got carried away with their new deluxe model erector sets and went way over budget seeing if they could use every piece.
All this tinkering makes bridges expensive, which is why the more modest engineers of the Chippewa Valley and Superior Railway Company thought up a cheaper idea for crossing the Mississippi from the mouth of the Chippewa River over to Reads Landing in Minnesota. Congress granted permission for that bridge in 1882.
The cheaper idea was simple: combine a bridge and a boat. Build a 400-foot-long span of the bridge on pontoons floating right on the water. When boats needed to pass by, the pontoon section could be just floated away, and pulled back after the boats went by. No girders or suspension cables, no piers or draw spans.
The pontoons were built at Peter's Boatyard in Wabasha in 1882 and floated up to Read's Landing. The bridge opened in November. It was the largest pontoon bridge in the world.
As you have likely learned, cheaper is not always better. When heavy train engines hit the pontoons, the whole section sank fourteen inches, forcing engineers to install hinged tracks at both ends. Trains went downhill and then uphill at the other end. Different water levels changed the height of the pontoons, and ice jams and floating debris made it necessary to stick wooden spikes all along the span to prevent damage. During the winter season, the pontoons had to be removed entirely to a safe harbor, cutting into railroad business.
The pontoon bridge had to be replaced in 1891, in 1907, in 1926, 1931, and 1939. The railroad begged Congress for permission to abandon the bridge, and this was granted in 1952, having taught the railroad an expensive lesson: boats seem to work better on the water than trains do.
Rock Island Lines is underwritten by the Illinois Arts Council, a state agency, and Augustana College, Rock Island.
