Pile bridge

A Trestle, also Pfahljochbrücke or pile bridge is a bridge in which the roadway rests on pile yokes. These are transverse to the bridge driven into the river bed pile couples with over the piles laid beams. The construction material is usually wood, concrete or steel rare.

History

Jochbrücken are among the oldest types of bridges. In Zurich remains were found in 1525 BC, belonging to a wooden bridge Rapperswil- Hurden. Also, the Celts and the Romans knew of the Trestle. Julius Caesar could, for example, in only ten days at Neuwied near Bonn build a bridge in this technology over the Rhine, which was 400 meters long and is known as Caesar's Rhine bridges.

Many stone bridges had as predecessors Jochbrücken that are no longer preserved. One of the oldest standing Jochbrücken in Europe is likely to be the Chapel Bridge in Lucerne. It was built in the 14th century and served initially as a battlement. The disadvantage of Jochbrücken are the relatively small openings, which disabled the one hand, the shipping and timber floating, on the other hand, were prone to be blocked at high water with floating debris or ice, so that the building has been damaged or destroyed completely equal.

Jochbrücken are still used today as temporary bridges because they can be set up quickly and make few demands on the individual components. However, they are also suitable for fixed structures for use - either as a building for secondary roads in wood or in concrete or steel design along with Plattenüberbauten. One of the longest Jochbrücken the Lake Pontchartrain Causeway is expected in the United States be, of the 38 km long and leads in the vicinity of New Orleans by a shallow sea.

Technology

A yoke or Pfahljoch is a series turned rammter piles that are above, connected to a horizontal ceiling beams, the yoke beam or Jochholz in construction. A number of such yokes being rammed into the riverbed and connected longitudinally with beams, it then usually lie in the transverse direction more beams which make up the roadway.

Is the ground too hard to einzurammen piles, a Jochschwelle is laid on the ground, in which the Jochständer be attached. This type of Jochen is called Schwelljoch.

The external piles are usually driven into the ground at an angle of bridges that are in strong flowing water in order to withstand the forces caused by the flow better. Sometimes additional piles in front of the yokes are driven into the ground, keep that drift ice and other floating debris from the yokes. The wooden construction is usually made of oak, as this wood is the most durable in the water. They are usually treated with tar to prevent them from drying out and disappear. In the Middle Ages the piles were provided with pole shoes. This ironwork simplifies the ramming of piles.