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Please refer to the comprehensive TechSpan® construction manual for a complete construction methodology.
- Set out and construct reinforced concrete footings as detailed.
- Set out centre line of base of arch elements and longitudinal location of the TechSpan® elements within footing keyway.
- Off-load and turn TechSpan® elements in the air.
- Use two cranes to erect the first four units. One crane should retain load until a stable formation is achieved. After this, the second crane may be released.
- Erect remainder of TechSpan® elements by placing each unit resting against the unit opposite and offset by half a unit width, allowing progressive support for subsequent arch units.
- Temporarily wire adjacent elements together.
- Cover vertical joints with impermeable membrane and/or geotextile.
- Apply bitumen bond break compound to base of arch units.
- Grout footing keyways.
- Backfill elements to arch crown.
- Construct the reinforced concrete longitudinal crown beam.
- Install joint material to crown beam.
- Complete backfill to finished surface level.
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Crew size and production rates
As a guide, a typical TechSpan® erection crew may include:
- crane operator, dog man and rigger;
- two workers to receive and set elements;
- one working foreman/supervisor.
RECO will provide on-site technical training to aid the installer with the first elements until the installer is competent with the technique. With smooth and careful operation by the contractor, it may be expected that 20 to 30 TechSpan® units can be erected per eight hour shift accounting for some 15 to 25m of tunnel, depending on the width of unit designed for the project. Installation rates generally depend on site conditions and should be discussed with RECO’s construction coordinator for guidance on particular project requirements.
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