9:00–10:43 pm, completion of culvert installation
Immediately after the final upstream section of culvert was placed at 9:10 pm, the 6 x high-tension steel threaded rebars were completely pushed through the 10.5m culvert. The multi-thread 80 ton post-tensioning of the culvert was executed using a Hydraulic Steel Rebar Tensioner. The task of tensioning the first tierod got underway just before 9:30 pm.
Placement and affixing of the two downstream wing walls
At the same time as the multi-threads were being post-tensioned, the balance of the TruLine crew completed the placement, joining and reinforced concreting in place of the two wing walls at the northern end of the culvert. This task got underway at 9:28 pm and was completed with the affixing of the two wing wall’s temporary prop at 10:45 pm. This event marked the end of the culvert install task.
After a 30 minute smoko, including a generous slap-up barbecue accompanied by lashings of hot food delivered to the site, backfilling the trench got underway. The trench was filled evenly on each side up to the level of the top of the culvert, care was taken to not disturb the box culvert alignment. Fill was done in well-compacted layers of AP65 with the layers not exceeding 30cm. The compacted haunching extended 1m either side of the culvert at the invert, and this fanned out progressively wider as the fill came up to 1.2m over the the 2.4m square box culvert. Then to finish 600mm of railway ballast was laid up to the rail level, at which point the trench was completely backfilled. The backfill was matched to existing ground condtions and extended out to the end of the North Side wing walls. The box culvert installation job was complete when the rail was lifted, levelled and reinstated.