Leonardo Da Vinci's Bridge

Italian renaissance man, Leonardo da Vinci remains one of the most famous artist, architect, engineer, scientist, naturalist and inventor from his or any other generation. Many of his concepts were hundreds of years ahead of their time, and Golden Horn Bridge is a perfect example of that.

In 1501, Leonardo da Vinci made a sketch of a 240-meters long single span bridge that was to be built over the Golden Horn – a natural inlet of the Bosphorus Strait dividing the city of Constantinople, present day Istanbul. This was the first time that such a long single span bridge was proposed. The construction methods that would be required to build such a structure would not come into use for another 300 years. Consequently, the bridge could not be built because it was too advanced for the builders of that time.

For five hundred years, Leonardo’s graceful design remained an obscure, tiny drawing in a corner of one of Leonardo’s voluminous notebooks, until 1996 when contemporary Norwegian artist, Vebjørn Sand, saw the drawing at an exhibition of Leonardo’s engineering designs. Sand was impressed by it that upon returning to Oslo, he proposed that the Norwegian Public Roads undertake the construction of the project.

For the next few years, Vebjorn Sand devoted his time and effort to transforming the Leonardo Bridge Project from a dream into reality. And in 2001, a small pedestrian footbridge based on Leonardo’s original design was built near the town of Ås in Norway, on highway E-18 linking Oslo and Stockholm. Converting the basic design in reality was done by Architect Selberg.

The pedestrian bridge is built on the same model as Leonardo da Vinci's original drawings, but instead of a massive arch stone bridge, the one in Ås has three glulam beams which runs in an arc across the road. On top of the glulam beams one can walk or cycle on. The total length of the bridge is 108 meters with main span width of 40 meters, height 10 meters and clearance of 5 meters.

According to the Leonardo Bridge Project’s website, the Turkish government has decided to build a full fledged bridge spanning the Golden Horn based Leonardo's design.

Leonardo’s sketch of the Golden Horn bridge.


Australia’s 5,614 Km Dingo Fence

The Dingo Fence or Dog Fence is a long fence that stretches from Jimbour on the Darling Downs near Dalby through thousands of kilometers of arid land ending west of Eyre peninsula on cliffs of the Nullarbor Plain. The fence was built in the early 1900's to keep dingoes or wild dogs out of the relatively fertile south-east part of the continent where sheep and cattle graze. At 5,614 kilometers, it is one of the longest structures in the world and the world's longest fence.

The fence was originally built in the 1880’s by State governments, initially to stop the spread of the rabbit plague across State borders. This proved to be a wasted effort and the fences fell into disrepair until the early 1900s when they were repaired in order to keep the dingoes out and protect the sheep flocks. In 1930, an estimated 32,000 km of dog netting in Queensland alone was being used on top of rabbit fences. In the 1940’s, the fences were joined together to form one continuous structure, which was recorded as the longest fence in the world. Until 1980, the fence was 8,614 kilometers long, but was then shortened to 5,614 kilometers.

The fence has been partly successfully over the years, though dingoes can still be found in parts of the southern states. The fence is maintained via its different states and councils to this day, at an approximate cost of 10 million dollars per year. Some parts of the fence is illuminated at night via solar panels feeding high output lights. The fence construction varies along its length, but generally it stands about 180cm in height and consist of miles upon miles of wire mesh clamped to timber posts. There is also an exclusion zone of about 5 meters on either side that is cleared of vegetation and is generally used as a track for service and maintenance.

Although the fence has helped reduce the loss of sheep to predators and save millions of dollars each year, it’s impact on the environment is hotly debated. Basically, the fence has created two ecological universes – one with dingoes and one without, contributing to the demise of some native animals and the endangerment of many more. Exclusion of dingoes has allowed for increased population of rabbits, kangaroos and emus, while native rodents, marsupials and grasses were all diminished.

On top of that, there is also debate on the actual native classification of the Dingo. Many believe that the Dingo is not a native to Australia but was introduced some 4000 years ago from South East Asia. Therefore it is an introduced pest like the rabbit, camel, buffalo and feral pig. In fact, land managers in most States and Territories are compelled through legislation to destroy wild dogs, including dingoes, on their land.

According to Dr. Mike Letnic, of the University of Sydney, the dingo, as Australia's top predator, has an important role in maintaining the balance of nature and that reintroduced or existing dingo populations could increase biodiversity across more than 2 million square kilometers of Australia.