In northern Rotterdam, the ‘De Groene Boog’ consortium, made up of BESIX NL, Dura Vermeer, Van Oord, John Laing, Rebel, and TBI-Mobilis,is connecting the existing A16 and A13 by constructing a new 11-km motorway, significantly improving Rotterdam’s accessibility. ‘De Groene Boog’ signed a contract with Rijkswaterstaat for the Design & Build of the infrastructure, along with a 20-year maintenance agreement. The project started in 2019 and works are set for completion by 2025.
A notable feature of the project is the 400-metre-long viaduct above the Terbregseplein, crossing a railway line and a motorway interchange. The viaduct has two decks, each for one direction, comprising seventeen segments ranging from 22 to 34 meters in length.
There are 2 types of segments. The “even” segments or diaphragm segments – with diaphragm beam – have a fixed length and their final location will be centered above the pillars. The “odd” segments – without diaphragm beam – are located in between the diaphragm segments. Their length depends on the distance between the pillars.
In the pictures below you can observe the various stages of fabricating a viaduct segment at the precast location. Each segment is manufactured within three weeks.
The three weeks’ construction cycle for a segment can be summarised as follows:
- Week 1: realisation of the bottom slab and walls (1 & 2 in the picture below)
- Week 2: realisation of the top slab (3 & 4 in the picture below)
- Week 3: tensioning all post-tensioning cables-transversal and longitudinal-and launch
Fabrication and launch of each segment in 8 steps:
Step 1 – rolling the reinforcement in the formwork:
Step 2 - installation of the formwork for the bottom slab and the walls:
Step 3 - casting of the concrete for the bottom slab and the walls in one phase:
Step 4 - installation of the formwork for the top slab of the segment:
Step 5 - reinforcement of the top slab of the segment:
Step 6 - concreting of the top slab of the segment:
Step 7 – tensioning - pre-stressing:
Step 8 – launch of the segment:
Launching the bridge
With 225,000 vehicles driving beneath the viaduct daily, closing it during construction was not an option. Hence, the consortium chose the Incremental Launching Method employing a 'launching nose'. The large blue cantilever steel structure shown in the picture below is used to guide the movement of each previously built segment from pillar to pillar.
Each segment is cast in connection with the previous one and prestressed. It is then pulled over a distance predefined in the launching sequence, a process repeated for each segment until the bridge is complete in its final position. Thorough calculations were conducted to ensure stability and prevent deformation of the steel nose. On-site monitoring confirms that the bridge behaves as expected. For more details on this method, click here. You can also view a timelapse of one of the segments moving over the Terbregseplein. Using the incremental launching method, segments are launched every Friday in the third week of the three-week cyclus, at a speed of +- 2.5 meters per hour. For segment 11, the last segment which was launched so far, the launching action was over 15 metres and took 7 hours. Sometimes the distance is up to 30 metres.
"When you've got a 'just do it' attitude and believe that nothing's impossible, you're already halfway there. But you know what makes it all happen? Teamwork. It's the most important ingredient that turns goals into reality. We're a bunch of individuals, sure, but together, we make things happen." – Peter Augustijn, Site Manager
Deck A in the southern direction is now complete. As for Deck B, in the northern direction, 11 segments have been built and launched toward their final positioning, with only 6 segments remaining. The completion of Deck B is expected by the second quarter of 2024. Kudos to the A16 Rotterdam team for their exceptional work on this impressive infrastructure project!
