The scale of the work is impressive. Six and a half thousand square metres of pad needing 720 truckloads of concrete, embedded with 1.4km of rail tracks.
Early on, the project’s construction contractor Martinus Rail suggested using fibre-reinforced concrete for cost benefit reasons. WSP involved a WSP UK-based expert to check this was fit-for-purpose. It was. Using this type of concrete did away with the need for 550 tonnes of reinforcing steel, resulting in 990 tonnes of carbon saved.
Pouring concrete can be a nerve-wracking experience at the best of times. Even more so here. With four tracks and six rail turnouts - mechanical devices that let trains switch from one track to another – hair-breadth precision is required.
“A lot of work is needed to fasten the turnouts - mechanical installations that allow trains to be guided from one track to another - and get them positioned. Plus, quality assurance before the concrete is poured,” says WSP team leader for civil engineering Mike Owen.
There’s absolutely no room for error, adds WSP service line leader for transport design Jaco Vorster.
“Rail brings complexity to a project. In civil engineering, the error tolerance is typically plus or minus 20mm; for rail, it’s 5mm; for turnouts, it's just 3mm.”
The new rail pad has been designed so that shipping containers trundling in on the new tracks can be lifted off with either straddle carriers or large forklifts.
As well as pad and track design, WSP has been responsible for geotechnical site investigations, QA reviews, construction support, and stormwater engineering.
Site investigations by WSP identified a better solution for managing stormwater running off the pad – one that’s set to improve discharge into the harbour.
In a major innovation, WSP is also harnessing its surveying capability as part of construction monitoring. Drones have been soaring skyward to take high resolution shots of project progress. Before and after images are combined in an online slide viewer that give a bird's eye view of what’s been happening.
In terms of rail projects, this has been one of Mike and Jaco’s top five.
“It’s been rewarding working on this practical solution for the Port - harnessing WSP, local and international, expertise all the way from concept design through to civil and stormwater engineering, quality assurance, and construction phase support,” says the pair.
“We’re excited to have played a role in helping improve the Port’s import and export capacity and, ultimately, minimise the kinds of disruptions they were experiencing before.”
Port Otago civil engineer Andy Pullar says the importance of having a cohesive project team for complex projects of this nature cannot be underestimated.
“We were lucky to have WSP on board through the design phase which flowed seamlessly through procurement and then into construction. The close working relationship developed between WSP and contractors Martinus ensured success for the project and is something everyone should be very proud of.”
With the last of the concrete soon to be poured and tracks laid down, the new rail pad is expected to be ready to roll later in August - bringing smoother freight movement, fewer disruptions, and a big step forward for the region’s trade future.
