Bascule bridges are impressive examples of the art of modern engineering. To enable ships to pass, one or two of the bridge's sections are raised and then lowered again. Bascule bridges are often chosen for places like urban areas that don't have enough space in which to build the high approaches required for conventional types of bridge. The emphasis is on causing as little interruption as possible to the flow of traffic both crossing and passing under the bridge. Therefore, the greatest challenge is to have the shortest possible opening and closing times. Waagner-Biro's Bascule bridges require opening times of between 90 and 180 seconds, depending on the requirements of our customers. Bascule bridges must operate with a high degree of reliability.
If a defect prevents a bridge from opening or closing, there are serious consequences on the flow of traffic. This means that the bridge's core element is its drive mechanism. Today, electro hydraulic drive mechanisms with hydraulic cylinders are the most economic type of drive mechanisms. They guarantee maximum effectiveness with the minimum of maintenance.
Swing bridges often move loads of over 1,000 tonnes in just a few minutes, thereby freeing a shipping channel. They are particularly suited as river crossings when high street or rail bridges are considered too expensive or would have too great an impact on the environment. When bridging major shipping channels, it might be advantageous to combine swing bridges and fixed bridges. When this option is chosen, the complete bridge structure has a higher crossing so that the headroom is sufficient for normal shipping and the swing bridge only has to be opened for the largest ships.
Most swing bridges are built as symmetrical structures with a central pillar so that two shipping lanes with unlimited headroom are available, one on either side of the pillar. Like all movable bridge systems, swing bridges must function quickly and efficiently to ensure an uninterrupted flow of traffic.
Vertical Lift Bridges
The traditional vertical-lift bridge has, up to now, been used to bridge rivers in crowded urban environments. They do, however, have a limited headroom for shipping traffic. The bridge's supporting structure is made of steel. This reduces the weight which needs to be raised and makes an operating hoist economically viable. A vertical-lift bridge is supported by cables which are usually connected to counter-weights that are positioned at the bridge's four corners. This compensates the bridge deck's weight and any residual load is raised and lowered using a winch.
On cable-stayed bridges, as on suspension bridges, steel cables bear the deck's load, but on cable-stayed bridges the cables are attached directly to the pylons. This reduces costs in comparison to suspension bridges. There is also, however, a reduction in the potential span, which, with a range of between 100m and 800m (with two pylons) is less than that of suspension bridges – even if, in exceptional cases, a span of 1,000m can be bridged. There are many types of cable-stayed bridges which are distinguishable by the pylon design (eg. A-Pylon, Y-Pylon, Middle Pylon, Two Pylon). As with suspension bridges, a defence against wind-induced oscillations is of particular importance. The solution found by the company demonstrates Waagner-Biro's know-how: it developed bridge sections with perfect aerodynamic designs.
Suspension bridges are known for their vast dimensions and they are, in fact, used to span distances of 300 to 1,500 metres. Subsequently, they are normally an impressive sight and suspension bridges often attain the status of tourist attraction.
For those attracted to the engineering: a suspension bridge has two pylons to which the main supporting cables are attached. Connecting cables, attached to the main cables, support the deck and the main beam below. It is the bridge's cables that carry the complete load. In addition to its own weight and the weight of the traffic, loads are generated by the wind, which are also transferred through the cables, along the pylons and into ground.
The plate-girder bridges – or box-girder bridges – offered by Waagner-Biro are suitable for many uses. The bridges come in many forms spanning many different distances. As composite structures, they have become economically attractive options. Their construction is of a reinforced concrete roadway set across a framework of steel girders. This combines the advantages of concrete (an economic roadway) and the advantages of steel (malleability, durability and re-enforceability). These types of steel bridges can be used to span up to about 250m.
Arch bridges are characterized by their elegant forms. Depending on the nature of the landscape over which they will stand, and the environmental conditions, Waagner-Biro construct bridges whose arches are above their decks (suspended deck), or bridges whose decks run above their arches (deck arch). Arch bridges are suitable for small constructions and for spanning lengths from 100m to 300m. It is also possible to erect many arches in a row.
If the weight of a bridge needs to be kept light, Waagner-Biro's truss bridges are a good choice. Because of the truss construction of their main support, the construction as a whole and its individual components (truss members) weigh comparatively little. This type of bridge is used for railway bridges, road bridges and other uses. Spans of up to 150m can be covered.
Not only people and their means of transport, but also oil and gas pipelines, conveyor belts, water pipelines or other heavy objects need to be transported over rivers and valleys. For these purposes, Biro-Waagner supplies pipeline bridges. These are equipped with a unique suspension system made from Y-shaped pylons that provide maximum stability. This stability is enhanced by a sophisticated central node that connects bearer cables and stay cables . This makes this type of bridge suitable for pedestrians, too. Waagner-Biro has already built many of these bridges with spans of over 300m.
Span: 100 - 500m
In the market for modular bridges, Waagner-Biro is one of the most respected suppliers. This type of bridging system was tailor-made for the rapid and simple provision and expansion of infrastructure. These bridges are built using a unit-assembly system that can be arbitrarily added to and each bridge can be adapted to meet the requirement of its site. Individual specifications for a bridge's width, span and load can be met using a modular bridge. Their normal span is between 35 and 60m. However, bridges with spans in excess of 120m have already been delivered. Generally, the length of the bridge is not limited and many individual bridges can easily be combined to form long chains of bridges. The width of the bridges vary from 4m for single lane, and 7m for two lane decks, but multi-lane module bridges are also available.
Flexibility is only one of the advantages of modular bridges. To ensure that they can be used in countries with less extensive infrastructures, Waagner-Biro designed the bridge's components in such a way that each bridge can be constructed using the simplest means by local, unskilled workers. The simplicity of the construction is exemplified by the fact that the components are bolted together on site, so no welding is required.
The flexibility and simplicity of modular bridges means that they are in high demand in less developed countries in South-East Asia and Africa. Every year, Waagner-Biro delivers about 100 bridges of this type to Indonesia and the Philippines and is a preferred partner of the local governments.
A special, extremely lightweight type of modular bridge is the panel bridge, a modular bridging system that consists of fixed-sized panel which are assembled to form the core of the construction.
The panels are single elements which are welded together to form a latticed framework. Each panel is 2.15m high and 3.048m long. Combining multiple panels forms the deck of the bridge. The cross members are also standardized and available in road widths of 3.15m, 4.20m and 7.35m.
This standardization makes possible an exceptionally short delivery time and very quick construction, because each element is produced for stock and can be delivered on demand within days.
THE ADVANTAGES OF PANEL BRIDGES ARE:
Exceptionally quick construction
Very simple connections of the elements to form a completed bridge
Short training period for personnel
Modular construction enables the simple adaptation to different spans, road widths and volumes of traffic
Very lightweight components
Simplified logistic processes
Use of standard panels
High-strength steel and a system height of 2.15 metres gives a high load capacity
All components are galvanized to protect against corrosion
The properties of panel bridges allow Waagner-Biro to offer, special services in addition to simply selling the bridges
Especially for makeshift bridges that will often be used for only a few months, Waagner-Biro also offers an attractive leasing option.
By storing the required amount of stock, single or double track bridges with a span of up to 40m can be delivered within a few day to areas suffering a disaster or emergency.
In addition to the delivery of the bridge, our customers receive comprehensive technical support from our team of civil engineers: structural analysis, system design, assembly instructions and supervision, and an inspection of the completed construction.
The applications of panel bridges are many. They include:
In case of an emergency or disaster (eg. flooding) uninterrupted access to the effected area must be provided as quickly as possible. Emergency bridges can be built as both road bridges and railway bridges.
Temporary bridges are used to maintain vehicle and pedestrian access to a site during the construction phase of a building project. Their simple assembly makes it possible for construction companies to build these bridges using their own workforces. Attractive leasing offers are available for short-term projects.
Thanks to their tough, rugged components and construction tools, Waagner-Biro's panel bridges are particularly suited for military operations. The bridging system's basic concept and its basic components are the same for military and non-military emergency bridges, and are therefore compatible. To calculate how each bridge will be configured in accordance with military load classifications, configuration tables for MLC 30-70 have been developed. Using these, after entering the desired span and width of a bridge, the required construction is given.