Incremental launch is a method in

civil engineering Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewage ...

of building a complete

bridge deck A deck is the surface of a bridge. A structural element of its superstructure, it may be constructed of concrete, steel, open grating, or wood. Sometimes the deck is covered by a railroad bed and track, asphalt concrete, or other form of pa ...

from one

abutment An abutment is the substructure at the ends of a bridge span or dam supporting its superstructure. Single-span bridges have abutments at each end which provide vertical and lateral support for the span, as well as acting as retaining walls ...

of the bridge only, manufacturing the

superstructure A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships. Aboard ships and large boats On water craft, the superstruct ...

of the bridge by sections to the other side. In current applications, the method is highly mechanised and uses

pre-stressed concrete Prestressed concrete is a form of concrete used in construction. It is substantially "prestressed" ( compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. Post-tensioned concreted i ...

History

The first bridge to have been incrementally launched appears to have been the

Waldshut–Koblenz Rhine Bridge The Waldshut–Koblenz Rhine Bridge is a single-track railway bridge on the Turgi–Koblenz–Waldshut railway, between Waldshut and Koblenz AG, crossing the Rhine and the border between Germany and Switzerland. It was the first railway bridge bu ...

, a

wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a ...

lattice truss A lattice bridge is a form of truss bridge that uses many small, closely spaced diagonal elements forming a lattice. The lattice Truss Bridge was patented in 1820 by architect Ithiel Town. Originally a design to allow a substantial bridge to be ma ...

railway bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, whic ...

, completed in 1859. The second incrementally launched bridge was the Rhine Bridge, a railway bridge that spanned the

Upper Rhine The Upper Rhine (german: Oberrhein ; french: Rhin Supérieur) is the section of the Rhine between Basel in Switzerland and Bingen in Germany, surrounded by the Upper Rhine Plain. The river is marked by Rhine-kilometres 170 to 529 (the sc ...

between

Kehl Kehl (; gsw, label= Low Alemannic German, Low Alemannic, Kaal) is a town in southwestern Germany in the Ortenaukreis, Baden-Württemberg. It is on the river Rhine, directly opposite the French city of Strasbourg, with which it shares some munic ...

, Germany and

Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label=Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the Eu ...

, France, completed in 1861 and subsequently destroyed and rebuilt on several occasions. The first incrementally launched

concrete bridge Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

was the

span Span may refer to: Science, technology and engineering * Span (unit), the width of a human hand * Span (engineering), a section between two intermediate supports * Wingspan, the distance between the wingtips of a bird or aircraft * Sorbitan ester ...

box girder bridge A box girder bridge, or box section bridge, is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinf ...

over the

Caroní River The Caroní River is the second most important river of Venezuela, the second in flow, and one of the longest, from the Kukenan tepui through to its confluence with the Orinoco River. The name "Caroní" is applied starting from the confluence ...

, completed in 1964. The second incrementally launched concrete bridge was over the

Inn River , image = UnterinntalWest.JPG , image_caption = Lower Inn valley from Rattenberg castle , source1_location = Swiss Alps (Lägh dal Lunghin) , source1_elevation = , source1_coordinates= , mouth_location = Danube (Passau) , mo ...

Kufstein Kufstein (; Central Bavarian: ''Kufstoa'') is a town in the Austrian state of Tyrol, the administrative seat of Kufstein District. With a population of about 19,600 it is the second largest Tyrolean town after the state capital Innsbruck. The great ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

, completed in 1965. The

structural engineer Structural engineers analyze, design, plan, and research structural components and structural systems to achieve design goals and ensure the safety and comfort of users or occupants. Their work takes account mainly of safety, technical, economic ...

s for both bridges were Professor Dr

Fritz Leonhardt Fritz Leonhardt (12 July 1909 – 30 December 1999) was a German structural engineer who made major contributions to 20th-century bridge engineering, especially in the development of cable-stayed bridges. His book ''Bridges: Aesthetics and Design ...

and his partner, Willi Baur. The usual method of building concrete bridges is the segmental method, one span at a time.

Method

The bridges are mostly of the box girder design and work with straight or constant curve shapes, with a constant radius. box girder sections of the bridge deck are fabricated at one end of the bridge in factory conditions. Each section is manufactured in around one week. The first section of the launch, the launching nose, is not made of concrete, but is a stiffened steel

plate girder A plate girder bridge is a bridge supported by two or more plate girders. Overview In a plate girder bridge, the plate girders are typically I-beams made up from separate structural steel plates (rather than rolled as a single cross-section), w ...

and is around 60% of the length of a bridge span, and reduces the

cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...

moment. The sections of bridge deck slide over sliding bearings, which are concrete blocks covered with

stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

and reinforced elastomeric pads.

Notable examples

Katima Mulilo Bridge The Katima Mulilo Bridge (also known as ''Bridge 508'' in the Namibian Bridge Register) carries the TransCaprivi Highway over the Zambezi River between Katima Mulilo, Namibia and Sesheke, Zambia. It is a road bridge, completed in 2004, 900 met ...

, 2004 * Redcliffe Bridge, 1986 * Woronora River Bridge, 2001, the largest incrementally-launched bridge when built *

Millau Viaduct The Millau Viaduct (french: Viaduc de Millau, ) is a multispan cable-stayed bridge completed in 2004 across the gorge valley of the Tarn near (west of) Millau in the Aveyron department in the Occitanie Region, in Southern France. The design te ...

, 2004, an example of launching a curved road deck

References

External links

* {{YouTube, S3Kf9e6JgF4, Bridge construction - Incremental Launching - 3D Animation Bridges by structural type Civil engineering Hydraulics