CREATE, the industry magazine for engineering professionals published a 6 page spread on our recent bridge rebuilding project in Papua New Guinea.
Working in a challenging environment can sometimes make any engineering project just that bit more difficult. Australian company Canstruct, had to knuckle down and get the job done during a multiple bridge build in Papua New Guinea. By Chris Sheedy.
A 2007 cyclone that brought an intense tropical low to Papua New Guinea (PNG) caused such heavy rainfall that hundreds died and major pieces of infrastructure were destroyed.
On 13 November the floodwaters, a result of Cyclone Guba, caused rivers to rise across Oro Province. Trees were uprooted and flung about like matchsticks by the angry waters. More than 200 people lost their lives and 20 bridges in the province were destroyed. Some of these were temporary structures, but they also included larger, steel girder bridges. Major road crossings on rivers such as Eroro, Gima, Ambogo and Kumusi had their abutments washed out or their mid-channel piers carried away.
Suddenly the local population was left, quite literally, high and dry and without access to basic needs such as work, markets, schools and health care.
In 2013, Canstruct, a family-owned and managed business based in Queensland, was contracted to design and construct the four major bridges that had been washed away six years earlier. No stranger to bridge building (one recent job included the rebuilding of 11 bridges on the Cairns to Kuranda Railway Line) or to working in remote environments (the company installed navigation aids in the Coral Sea, 400 km off the Queensland coast), the business got to work on planning their Papuan engineering extravaganza.
“It is a very hard environment,” says Dan Murphy, Director and Senior Project Manager of Canstruct. “One thing I severely underestimated at the beginning of the project was the levels of maintenance of equipment that were required. In the end I had to double the budget for spare parts and maintenance. It was very trying. It’s one thing to break an excavator, or to need a new hose. But to get that hose or some other spare part to the site was torturous. You send one and it would get lost, then you send another one and meanwhile the machine is down for a week. It was completely isolated. There was virtually nothing that we could source locally. So logistics was the real challenge.”
Initially, Dan says, containers filled with spare parts for various machines were sent to the sites. But often it was the parts that had not been sent that were needed. “I’ve still got lots of gearboxes for some obscure kind of ute,” Dan laughs. “You have to get your supply chain right and we struggled with that at the beginning. Deeper into the project we got it right.”
Fruit and meat, and other food for the workers, was often imported from Australia. And many of the workers themselves were sourced locally, after a carefully planned public relations campaign.
Hearts and minds
Canstruct staff were sent into the region first, before any work began, to engage the local communities. Workers could not be transported from one job to the next, as the destroyed bridges were spaced over a distance of about 100 km arid were therefore on the land of different tribal groups, so each site required its own crew. Those tasked with engaging local workers set up sponsorship of sporting events and handed out items that would help local communities, such as pedal-powered sewing machines, coloured pencil sets and sports equipment.
“We needed the local people to realise that the guys from Canstruct are okay, that we were there to help them,” Dan says. “We bought trophies and went to rugby league games in the bush, which was grand. I had a terrific time doing it.”Over 300 local people were employed” Dan says.
Then the seriously hard work began. “The rivers are wide and flat with steep banks, which is a constant challenge, especially for piling work,” he says. “It rains a lot and that’s not so good for building roads or putting down concrete, plus it’s relentlessly hot. We just had to work around those bridge under conditions and be flexible with the schedule. If one construction. river was flooding, it didn’t necessarily mean the others were. And thanks to the sudden nature of the flooding, we could never leave equipment on the riverbed overnight.”
A volcano had erupted in 1951, killing thousands of people, meaning the ground was filled with long sections of rock and boulders that had once been part of a molten flow. Drills snapped, engines blew and machinery buckled. The rain descended, the heat suffocated and the teams waited for replacement parts. Bit by bit the bridges took shape, just as they had decades earlier.
The father figure
Robin Murphy, Dan’s father and the founder of Canstruct, first began building bridges in Papua New Guinea in 1963. His wife moved there 12 months later and their daughter Jane, now the business’s Communications Et Engagement Manager, was born in PNG. Robin’s son Adrian, also part of the business, was born there, too.
An almost 60-year member of Engineers Australia, Robin graduated from University of Queensland with a civil engineering degree in 1961 and moved to PNG to build bridges on behalf of the Australian Government. “I designed some of the major bridges in the country even though I was only 23 or 24 years old at the time,” Robin says. “And then I was made a District Engineer, looking after an entire province, at the age of 25. I had a workforce of 1000 locals and about 20 expats.”
So the Murphy family really is no stranger to building bridges in PNG, although never in the Oro province. They first heard rumblings about the new bridges contract in 2011. “The flood in 2007 was a once- in-2000-year event,” Robin says. “Every bridge in the province was washed away, most designed by a well- known engineering consultant for a 100-year flood. When they were hit by a 2000-year flood, the bridges disappeared overnight, the whole lot of them. We found steel three kilometres downstream – big steel beams with the concrete still attached. It’s a very treacherous place.”
“So during this project there were physical challenges such as the river itself. But as Dan said, the real problem was logistics. This is a very remote area. The only thing we could buy locally was fuel and poor-quality timber. Everything else we had to bring in. We shipped in three 80 to 100-t cranes. We had about 20 to 30 trucks and vehicles of all descriptions. AU of that had to be brought in and maintained.”
Security could also have been an issue, Robin says. Often when large businesses send staff to PNG they lock them up in secure compounds and tell them to never go out without armed guards, but Canstruct took a different tack. “We spent a lot of time and effort and money trying to befriend the locals and we had an excellent relationship with them,” he says. “After the bridges were finished the Governor of Oro Province, Gary Juif a, said. “We have come to know Canstruct. They have been part of our community. Even when they leave they will be in our hearts.” That was a great testament to our success in bonding with the community.”
Dan was honoured to be made a chief during the three-year build, and Robin was inducted into a tribe during a particularly memorable ceremony. “It was an absolute hoot,” Robin smiles. “They gave me a hat and chains of office, which is like a mayoral chain except it’s made of boar tusks. They also gave me a killing club, a live pig and half a truckload of sweet potatoes and yams. At least the pig had something to eat!”
Going Pile High
Piling for the Oro Bridges project was originally designed as groups of H-piles at each pier and abutment location. Canstruct staff simplified the piling design by substituting the large number of H piles with two heavy-walled circular hollow section (CHS) piles at each pile bent. These were continued up to the underside of the headstock, eliminating construction of pilecaps In the river bed.
Piles had to be driven much deeper than the geotechnical reports originally Indicated. At three sites, piles required greater length to achieve capacity for the structural design. Boulder obstructions were encountered in the river bed. The Canstruct team had to be innovative in their thinking to overcome these issues. They used the available length of pipe on site to complete the majority of the first three bridges then additional lengths were ordered. In the end, two additional shipments of piles from Australia comprising 22 X 12 m pipe lengths were required.
The majority of installed piles were longer than 20m and the total number of piles across all bridges was 36. The total length of pile driven for the project was 915m.