Two types of convicts helped to build the Great North Road: the Road Gangs and the Iron Gangs.
Criminals sent to Australia from their native Great Britain made up these two gangs. However, those in the Iron Gangs had re-offended since their arrival in the country. They were constrained by leg-irons, which could only be removed by a blacksmith. Road Gangs were less restrained, but were still required to work under the watchful eye of an overseer.
During the construction of the road, some of these convicts absconded and were either caught or came back on their own accord. The dense bushland and the fact that the road was in the middle of nowhere gave them no other option, says Dharug & Lower Hawkesbury Historical Society Inc. member, Jan Kofron. “It was a totally inhospitable country. They had to battle the elements and there are records of people who were killed,” she says.
The construction of the 240-kilometre route connecting Sydney to the Hunter Valley region began in 1826. NSW Governor Ralph Darling instigated the construction of the road, and Assistant Surveyor Heneage Finch surveyed the road’s original line in 1825.
Construction began in 1826. Many parts of Finch’s original plans were deemed far too steep and treacherous. One such section was the Finch Ascent, which was abandoned by Governor Darling in 1828. “It was decided that they should look for a different, slightly easier route,” says Ms. Kofron. They began construction of the alternate route, the Devine’s Hill Ascent, in 1828 under the supervision of Assistant Surveyor and former British Army Officer, Percy Simpson.
This is the area crossing Hawkesbury and down through to Wisemans Ferry and Newcastle. Ms. Kofron says Mr. Simpson was an engineer from Great Britain who brought modern ideas for road construction with him. This section of road, under Mr. Simpson’s guidance, provides a good example of the innovation used in the construction of the road, she says.
These convicts didn’t have much in the way of building expertise, Ms. Kofron adds. But the innovation and techniques used in the construction of the Great North Road were nevertheless a huge feat of civil engineering.
The Devine’s Hill Ascent begins with a descent into Wisemans Ferry and a climb up to the other side, limiting the use of horse and cart. The sandstone used for the road’s walls and buttresses had to be quarried on-site. It is particularly difficult material to work with, says Ms. Kofron. In teams of two, the convicts would work together to prep large rocks in the quarrying process. One worker would hold a long metal rod, also known as a jumper bar, in place while the other hit it with a hammer. Each time the jumper was struck, the iron turned. The jumper bar would dig a hole, which would then be filled with gunpowder. The rocks were blasted to widen the road and then cut into blocks for the walls and buttresses. The chips from the rock would be used in the road’s pavement.
Mr. Simpson introduced sophisticated inlet and outlet stonework for the road’s culverts, particularly on the Devine’s Hill Ascent. A massive wall was erected with buttresses to support it on the road’s ascent and steep hillsides. The buttresses supporting the wall had a culvert outlet near the top with a race for the water to cascade down without eroding the wall or the valley slope. Other culverts and drainage elements were installed to effectively keep water away from the road’s surrounding walls and buttresses.
The convicts used wedges, mallets, axes and other tools in the construction of the road. Ms. Kofron says a pulley system they may have used in the process: “Up on the higher buttresses, there were rocks on it that are around 600 kilograms, so it would be impossible for two men to lift, but they’ve never found evidence for [a pulley system].”
The Devine’s Hill Ascent was completed in 1832 and the remainder of the road was completed by 1836.
The Great North Road was listed as an Australian National Heritage site in 2007. The Devine’s Hill and Finch’s Line sections were listed as World Heritage sites in July 2010. Nearly 48 kilometres of the Heritage Listed area has been closed off to the public. Nearly 80 years later, despite the primitive construction methods, the 48 kilometres of the Heritage Listed area stands today in pristine condition.