In a New Zealand first, CSP Pacific’s Super•Cor® Arch is being used for a culvert across Whakaruatapu Stream near Dannevirke on SH2. The existing level viaduct-style bridge built in 1927, named the ‘skinny bridge’, has long since been a concern for the New Zealand Transport Agency and locals because its width of 5.79m means it can’t accommodate trucks passing other vehicles. In addition, the weakening state of its foundations means it is no longer seismically safe.
When looking at replacement of the ‘skinny bridge’ the Transport Agency considered a completely new bridge – but it was not the preferred option. In addition, standard culvert options were not 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.
“We are the sole distributor of Super•Cor® structures in New Zealand,” explains Jeremy Mallender, Sales Engineer – Lower North Island for CSP Pacific. “They are manufactured by Atlantic Civil Products in Australia and used throughout Australia as they have the ability to span up to 25 metres and can carry tremendous loads. This makes them perfect for use in the mining regions of Australia - and now for New Zealand’s first installation in this technically challenging location.”
The new 116m long x 6m wide Super•Cor® Arch culvert is being located at the base of the existing gully and will eventually house the Whakaruatapu Stream. Installation is being undertaken by Stringfellows Contracts Ltd. “We started work on site in late November and the first task we had to complete was the diversion of the existing stream into a manmade watercourse, so we could carry out the construction of the culvert without affecting the stream’s flow,” explains Simon de Rose, Contracts Manager for Stringfellows. Once the new watercourse was completed ecologists were on hand to ensure that the stream and fish were diverted safely and successfully. The same process will happen in reverse when the new culvert is in place and the stream is redirected back through it.
Simon and his team have also completed excavations for the new concrete foundations of the culvert. “We have poured site concrete so we have a platform to work from and we are now in the process of working on the steel work for the foundations which will eventually be bolted to the Super•Cor® Arch. The concrete trough foundations - designed by Opus Consultants in partnership with CSP Pacific - are quite impressive and designed to carry and spread the load of the fill through the arch culvert to the siltstone material below. The foundation will be 9.3m wide, 800mm thick and contain over 1000m³ of reinforced concrete. It’s very well engineered.”
The foundations will be poured in four sections enabling construction of the arch to continue behind Simon and his team as they move onto the foundations for the next section. With all the components for the Super•Cor® onsite Simon explains that he is grateful for CSP Pacific’s support so far. “Jeremy and Mo have been on site a couple of times to check we are all under control and will be on site again when construction of the arch gets underway. We have worked with CSP Pacific for many years and have a great relationship with them.”
|A plan of the 116m culvert with two 15° bends which will follow the contour of the stream|
With so much still to do Simon says that the Super•Cor® is a first for them too and that the excavation of more than 150,000m³ of earth will be the easier of the two tasks.
Keep an eye out for updates of the installation of New Zealand’s first Super•Cor® Arch culvert in the next issue of Road Rave.