The history of the Schlei bridge in Kappeln dates back to the year 1867. Upon the request of many merchants in Kappeln, a pontoon bridge was built. This 180 metre long bridge stood on 18 cranes which were able to open the bridge at its deepest spot.

Even the rail tracks of the Eckernförde railway ran over the bridge. The engine and cars together exceeded the weight limit of the bridge so that the cars alone had to be pulled over the bridge by horses. There was also a fee for using the bridge. Climate and shipping adversities caused regular damage to the bridge.

In 1927, the pontoon bridge was replaced with a swing bridge. At first, the structure of the bridge in Lindaunis was planned to be used in the new bridge, but the plan was later rejected as the traffic volume around Kappeln already became a problem.

The bridge construction had an operational turning part and an extremely high weight limit to carry two locomotives with 50 tons each including their cars with total of 18 tons.

Since the traffic volume kept increasing, the swing bridge was soon to reach its capacity and in the 1980s a new plan came up to build a tunnel. This project, however, was not feasible as the costs were too high and a high bridge would not have fit into the townscape.

Instead a two-winged double-flap bridge was built, which opened on April 27, 2000, regulating ship and vehicle traffic through Kappeln. To this day, the Schlei bridge works like a charm.