How can a six lane motorway bridge be replaced without interfering with the flow of traffic on and under the bridge? In a pilot project with DEGES, Arup shows how this complex design challenge can be met.
For the demolition and replacement of the Schwelmetalbrücke, we are using Building Information Modelling (BIM) – the first time in Germany for the complete construction of a road bridge – setting forward-looking standards in terms of construction efficiency. BIM is not only used for planning but is also the basis for construction supervision, cost control, construction sequence planning and as-built documentation.
Every day, 100,000 vehicles travel across the six lane, 207 metre long bridge, which spans a railway line, a federal and regional road and the River Schwelme.
Since the structural elements of the concrete bridge built in 1969 no longer meet today's structural capacity requirements, they will need to be replaced. Construction work has started and will be carried out in several stages over a period of four years - with continuous traffic operations both on and below the bridge.
100,000vehicles travel across the bridge every day
6-lanebridge of the A1 (one of the busiest motorways in Germany)
The demolition and construction process
Our goal with the project is to avoid traffic interruptions to vehicle and train journeys where possible. For this reason, we have developed a very detailed demolition and construction plan that takes into account the very restricted space underneath the bridge, where there is not enough space for a crane or the storage of components and construction elements.
Our design enable the girders of the new bridge to first serve as a large gantry: the steel structure of the new bridge will be built before the old bridge segments are demolished and will be erected above the existing bridge. The new steel girders will then be placed on temporary support trestles and be used to lower the dismantled bridge segments. Due to the lack of space, the bridge sections have to be lowered piece by piece and moved longitudinally to the demolition areas. A particular challenge was the design of the new bridge girders, which had to be designed for their dual function as demolition gantry and bridge girders.
The use of BIM for the design of the Schwelmetal Bridge shows that such complex projects can be planned and realised much more precisely, economically and sustainably. The complex traffic routes could be planned efficiently in advance, so that traffic disruptions can be largely excluded ” Markus Gabler Germany Bridge Design Leader
Everything at a glance: 5D design with BIM
Due to the complexity of the project, we use the BIM method for both the design and construction process with 5D planning, i.e. including time and cost planning. This is a novelty in Germany, where BIM is rarely used in bridge construction and only for individual design steps.
By depicting all disciplines and special fields, the existing and new planning can be clearly represented in the BIM model. Additional information - e.g. on subsoil, groundwater level and deep foundations, obstructions, anchors, sewers and technical installations - also makes it possible to identify possible clashes at an early stage.