Aqueducts have been used to transport water for millenia, back to the ancient Romans. While we often think of these man-made waterways as elaborate stretches of canal, there’s one that’s quite the opposite.
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The Veluwemeer Aqueduct is thought to be the world’s shortest official aqueduct. Located in Harderwijk, Eastern Netherlands, this small waterway is only 25 meters long and 19 meters wide. However, the fact that the aqueduct is short is perhaps the least interesting aspect. More interesting, is the fact that it travels directly over a major highway.
The Veluwemeer aqueduct was constructed over the N302 road where 34,000 vehicles pass each day. While roadways usually get constructed over water, in this case it was deemed more cost effective to have the water go over the road.
The Veluwemeer is just 3 meters deep, but it allows for small boats and other watercraft to pass over the busy highway when needed. There also happens to be walkways for people on both sides so visitors can walk across. This peculiar layout of infrastructure allows for constant traffic flow while allowing boats of indefinite heights to pass over top.
Opened in January 2003, the unique water bridge is still in operation today. Before its construction, engineers considered creating an underwater tunnel or even a tall bridge, but for this specific purpose, both cases were deemed too expensive and too obstructive to the landscape. Locals simply needed a way to let cars continue their commute and tall sailboats to continue their sail.
As for the engineering of this bridge, it’s shortness lends to a rather simple design. Construction began in 1998 and design work was done by the engineering firm Grontmij Maunsell. An initial budget was set at around 53 million Euros, roughly 61 million USD.
Anchored steel sheet piling was used to hold back the sediment for the roadway to allow it to dip below the water line. This process is much in the same as temporary cofferdams are used in underwater construction projects. Rather in this case, they were permanent.After the steel sheet was put into place to form the roadway, the bridge was poured with four spans of concrete stretching 27 meters.
The deck itself is made up of prestressed concrete, which is a process that allows for concrete beams to hold high loads of tension. The entire project was estimated to have consumed 22,000 cubic meters of concrete. Engineers also calculated the necessary size of the bridge and its inlet based upon the maximum flow rate, .7 meters per seconds, of the lakes that it connects. When it was all said and done it took four years to construct and is still functioning today.