Engineering feat takes centre stage at Snowy

With its rolling plains, snow-capped mountains, and sharp twists and turns, a 26.5 metre B-triple isn’t something you’d usually expect to find navigating its way through Cooma, the largest town in the Snowy Mountains.

But come February, the first of 14 PBS-approved B-triple sets will be doing exactly that. The innovative combinations will reduce the total number of trips to site from 43,500 trips down to just 14,500, over the course of three years.

Built by local specialist trailer manufacturer Midland Pty Ltd, and pulled by 6×6 Scania G540hp prime movers, which are the first prime movers in Australia to feature automatic snow chains.

These innovative combinations will play their part in helping to shape Australia’s largest committed renewable energy project, Snowy Hydro 2.0.

The Snowy Hydro 2.0 project will involve linking the Tantangara Dam with the Talbingo Dam via 27 kilometres of tunnels, as well as building a new underground power station.

The mammoth project is expected to be operational by early 2025, providing on-demand energy as well as energy storage.

The waterway tunnels will be lined with 6.5 tonne precast concrete segments, produced at a factory in Polo Flat, Cooma.

The dedicated team of 28 staff members at Midland Industries that helped to turn the trailer concept into a reality.

The segments will form rings for the tunnel, with nine segments in each ring. Up to 130,500 concrete segments will need to be produced and transported to the two tunnel boring sites at Lobs Hole and Tantangara. It’s roughly a 200-kilometre round trip from factory to the tunnel site and back and again.

Scania will supply 16 prime movers – 14 that will be paired up with the trailer sets, along with two extras. One will be there as a spare in case a truck is out of action due to breakdown or maintenance; while the other will be used to assist if a vehicle struggles to come up through the snow, by helping to push it up the mountain.

These 6×6 Scanias feature a newly released six-cylinder engine.

“These will be the first 540hp 6×6 Scania prime movers. They’ll also feature Rud Rotogrip Automatic Snow Chains, imported from Germany, which we’ve never fitted before – usually you see that around Europe, the United States and Canada, but not in Australia,” said Michael Farrell, Scania Account Manager for Prestons in Sydney.

“The chains are under the truck, so they keep spinning around and as they are spinning, they go under the tyres. The truck can engage the chain automatically.”

Scania won the contract following a tender process.

“The trucks needed to have enough horsepower to cope with the weights they’d be pulling, because the loads are quite heavy, but they couldn’t go over the axle limits. Then it came down to cost as well because it’s such a big job. We ticked every box of what was needed and they came back and wanted to proceed,” Farrell added.

Midland Pty Ltd was first contacted by the Snowy 2.0 project team in February 2019 and met with them in August that year. What they required was to be able to transport 63 tonnes worth of concrete segments per load.

Though the original plan was to use a quad axle low loader, that wasn’t viable, so instead the team of engineers developed a 26.5 metre B-triple combination, capable of achieving a Gross Combination Mass of 91 tonne.

According to Midland, over $400,000 was spent on research and development, with computer simulations used to test out various trailer designs on the arduous route.

“The road was a big challenge for us,” explained Trimmer.

“The last 12 kilometres of the run is dirt, down into the bottom of the Snowy Mountains. We ran 60 finite element testing simulations, which simulated the road in the computer software and then ran the loaded trailer through it. We had to ensure crack elimination to make sure it lasted. Tare weight was another major challenge. We couldn’t just throw steel at it to make it heavier.

“The roads are so windy – one corner has a 12.6m internal radius. We had to make sure the whole combination could navigate that corner. Being so long, you’re going to get massive amounts of twist in the trailer, but with the payload being concrete, it doesn’t twist.”

Trimmer said that the combination’s manoeuvrability was aided by its very short wheelbase and Jost ballrace turntable.

“It ensures we get good manoeuvrability and keep even pressure, allowing for the twist behind the truck so it tracks better. You could do a U-turn at a roundabout with no problem. There are three roundabouts these trucks will have to navigate on their route through Cooma.

“We wanted to keep the combination as short as we possibly could. We had to stay under 28 metres to navigate the roads. It took some time getting our centre of gravity right to ensure stability on the mountain roads, and wheel spacing was a big thing so we weren’t damaging the roads.”

After a long 18-month process, production finally began in October 2020.

When Trimmer spoke with Big Rigs, the first of these B-triple sets had been completed, with all due to be finished by March. Now that the trailers are well and truly in production, the next big challenge is load restraint.

The trailers will use a unique lashing system, with hydraulic tensioning control and a warning light that alerts the driver of any pressure reduction.

“The straps will be powered by hydraulics that operate from the trucks and we need to certify that to -20°C operating conditions, as concrete that’s frozen can become quite slippery,” added Trimmer.

A unique rubber coating will be put onto the load restraint bolsters and the load restraint straps will be made out of a special webbing material called Dyneema.

“Generally over here we use polyester or nylon, but this is a much stronger product with very little stretch so it protects the concrete and ensures it doesn’t move,” explained Trimmer.

Though the project has been quite challenging, Trimmer said it was also very rewarding.

“A lot of learning has come out of it that we can use to improve our processes going forward.”

At a time of so much uncertainty, with COVID impacting so many jobs and livelihoods, it’s also provided employment opportunities too.

Midland employed eight additional staff as a direct result of the Snowy 2.0 project, bringing its workforce up to 28. The project has injected approximately $9 million into the local economy too.

To add, the Snowy 2.0 project will employ 42 drivers to steer these beauties, with specialist training provided; and Scania will set up a remote workshop in Cooma, which will be staffed 24 hours a day, to make sure the trucks are kept on the road.

“This is a very unique project for us and for Australia,” said Trimmer.

“The ability to provide employment opportunities for a lot of people during these COVID times has been good for a rural country town. The Snowy 2.0 project is good for the economy and it’s so good to be part of it.”

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