Magdeburg Water Bridge(near Berlin)

The giant kilometer-long Magdeburg Water Bridge, completed in October 2003, connects two important German shipping canals, the Elbe-Havel canal and the Mittellandkanal, which leads to the country’s industrial Ruhr Valley heartland. Engineers first conceived of joining the two waterways as far back as 1919 but construction was postponed during the first and second world wars. After the Cold War split Germany, the project was put on hold indefinitely. Construction began in 1997 and after six years and around half a billion euros the gigantic water bridge now connects Berlin’s inland harbor with the ports along the Rhine river. As Europe’s longest water bridge, it measures just short of a kilometer at 918 meters.

The huge tub, created to transport ships over the Elbe, took 24,000 metric tons of steel and 68,000 cubic meters of concrete to build.

To those who appreciate engineering projects, here's a puzzle for you armchair engineers and physicists:

Did that bridge have to be designed to withstand the additional weight of ship and barge traffic,or just the weight of the water?

Answer:

It only needs to be designed to withstand the weight of the water!

Why? A ship always displaces an amount of water that weighs the same as the ship,regardless of how heavily a ship may be loaded.