Underslung Form Traveller
A self-launching form traveller for cast-in-situ balanced cantilever construction, carrying its formwork below the deck so that the space above the segment stays clear.
Key specifications
- Segment length
- 7–10 mAs required in cable-stayed bridges
- Segment weight
- 50–450 tIncluding concrete and formwork
- Launching
- Self-launchingAutomated, forward and backward
- Configuration
- UnderslungClear space above the segment
What an underslung form traveller does
In cast-in-situ bridge construction, the underslung form traveller suits balanced-cantilever work that requires unobstructed clearance above the formwork. The traveller structure is carried beneath the deck rather than over it, so the area above the segment remains free. This makes the configuration suitable for cable-stayed bridges, arch bridges and segments incorporating prefabricated steel cages.
The underslung arrangement also reduces the overall load imposed on the structure while maintaining high stability. Each traveller is engineered around the specific bridge design, load conditions and construction timeline rather than supplied to a fixed standard.
Applications and construction method
The construction method is cast-in-situ balanced cantilever. The underslung configuration is selected where clearance above the formwork matters, or where longer segments are required.
Suitable structures and situations
Ranges, capacity and design considerations
Segment range and capacity
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| Segment length | 7–10 m, as required in cable-stayed bridges |
|---|---|
| Segment weight | 50–450 t, including concrete and formwork |
| Launching movement | Automated self-launching, forward and backward |
| Additional lifting equipment | Reduced requirement |
Advantages and design considerations
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Suited to longer segments
Accommodates the 7–10 m segment lengths required in cable-stayed bridges.
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Load capacity
Handles segment weights from 50 to 450 t, including concrete and formwork, giving adaptability across a wide range of project requirements.
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Self-launching efficiency
Automated forward and backward movement reduces downtime and the need for additional lifting equipment.
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Reduced load on the structure
The underslung configuration lowers the overall load imposed on the structure while maintaining high stability.
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Fewer construction cycles
Greater segment capacity means fewer cycles and shorter programme durations.
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Engineered per project
Custom engineering support optimises the traveller for the specific bridge design, load conditions and construction timeline.
Underslung compared with overhead
Both configurations build by cast-in-situ balanced cantilever and both are self-launching. They differ in segment range, weight range, and where the traveller structure sits relative to the deck.
Swipe or scroll horizontally to view the full table.
| Property | Underslung (this page) | Overhead |
|---|---|---|
| Segment length | 7–10 m | 3–7 m |
| Segment weight | 50–450 t | 100–450 t |
| Shortest pier segment | Not specified | From 5 m (hammerhead) |
| Clearance above formwork | Unobstructed | Not specified |
| Self-launching | Yes, forward and backward | Yes, forward and backward |
| Particularly suited to | Cable-stayed and arch bridges; prefabricated steel cages | Shorter hammerhead pier segments |
Form travellers in service
Underslung and balanced-cantilever form traveller installations, showing working platforms, formwork and position relative to the deck.
Related equipment
Discuss your form traveller requirement
Tell us the span arrangement, segment geometry and programme, and our team will respond to your enquiry.