New Zealand’s first Super•Cor® Arch is being used as a culvert across Whakaruatapu Stream near Dannevirke on SH2 and replaces the existing level viaduct-style, aptly named ‘skinny’ bridge built in 1927. Stringfellows Contracts and subcontractor Morris & Bailey have been working on construction of the new culvert since April with the help and support of CSP Pacific.
“The project is at an interesting stage as we have completed about 50 m of 116m and are about to get to the 15 degree elbow,” explains Simon De Rose, Contracts Manager for Stringfellows. “Things have gone together very well. The weather has been tricky at times but everything is going to plan and we are on target. All the corrugated sections have fitted spot on without any problems. Both Jeremy and Mo from CSP Pacific have been really great. It’s interesting that the margin of tolerance allowable on this job is 1% and we are at under 0.5% so things are going really well.”
Simon says the project has created a tremendous amount of interest. “We had thought that this project was just a first for New Zealand but it is also an Australasian first for Super•Cor® with elbows.”
When looking at replacement of the ‘skinny bridge’ the Transport Agency considered a completely new bridge along with standard culvert options – the latter not being suitable due to the depth of the gully to the stream and the considerable amount of backfill required to reach road level. Ultimately CSP Pacific’s Super•Cor® Arch structure was the only option capable of carrying the fill load of 16m over the top of the culvert.
“From an engineering perspective the culvert has many components to it to ensure it handles the extreme weight of the 16m of fill that will be above it in various sections,” explains Jeremy Mallender, Sales Engineer – Lower North Island for CSP Pacific. “When looking at the photos you can see that the ribs are bolted on top of the barrel, opposite to the peaks and troughs of the corrugation. You can also see access holes at the top and bottom of the ribs, which is where they will be filled with a concrete grout creating EC ribs or encased concrete ribs. Once the ribs have been filled, an additional concrete foundation will be poured along the base encasing the steel ‘U’ bends and the bottom of the ribs. This creates the strength in the culvert to carry the weight above. It's a very integrated system.”
With the completion of the culvert construction and the backfill of more than 150,000m³ of earth, there is still a lot to do at the site. Look out for an update in future issues of Road Rave.