Gairloch Bridge facts for kids
Quick facts for kids Gairloch Bridge |
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Gairloch Bridge, circa 1890
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| Location | over the Herbert River at Old Bruce Highway, Ingham, Shire of Hinchinbrook, Queensland, Australia |
| Design period | 1870s - 1890s (late 19th century) |
| Built | 1890 - 1891 |
| Architect | Alfred Barton Brady |
| Official name: Gairloch Bridge | |
| Type | state heritage (built) |
| Designated | 17 July 2008 |
| Reference no. | 602591 |
| Significant period | 1890 - 2008 |
| Significant components | pier/s (bridge), abutments - road bridge, road/roadway |
| Builders | James Graham |
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Gairloch Bridge is an old and important road bridge that crosses the Herbert River near Ingham, in Queensland, Australia. It was designed by a famous engineer named Alfred Barton Brady and built between 1890 and 1891 by James Graham. This bridge is so special that it was added to the Queensland Heritage Register on July 17, 2008, which means it's protected for its history.
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Why Was Gairloch Bridge Built?
The Gairloch Bridge is a low bridge that crosses the lower Herbert River near Ingham in North Queensland. It was finished in November 1891. Its design was very new for its time and was created by Alfred Barton Brady, a well-known engineer for the Queensland Government.
The Herbert River valley was first settled by farmers raising animals in the mid-1860s. Growing sugarcane, which is now the main industry there, started in the early 1870s. By the late 1880s, the Ingham area had become one of Queensland's best sugar producers. About five sugar mills were working in the Herbert River area.
Calls for a Bridge
As early as 1885, local groups and people living in the area asked the Queensland Government to build a bridge. They wanted a bridge across the Herbert River to make it easier for farmers on the north side to reach the seaport. This port was south of the river mouth at Dungeness.
When the government didn't agree to pay for the bridge, the local board decided to find the money themselves. In June 1888, they asked the Government Engineer for Bridges to draw up plans for the bridge.
Who Designed the Gairloch Bridge?
The bridge was designed by Alfred Barton Brady. He was a civil engineer and architect born in England who moved to Australia in 1884. From 1885, he worked as an Assistant Engineer for Bridges with the Railways Department in Queensland. In June 1889, he became the Acting Engineer for Bridges in the Department of Mines and Works.
Brady had a very successful career in these departments. He became the Government Architect and Engineer of Bridges in 1892. Later, he became an Undersecretary in 1901, a position he held until he retired in 1922.
Building the Bridge
The job to build the bridge was given to James Graham from South Brisbane. He started work in early 1890. There were several delays, partly because the river often flooded. The bridge was finally finished at a cost of £7,737 and opened for traffic on November 4, 1891.
The Gairloch Bridge was the first road bridge Brady designed as Engineer for Bridges. He also designed other important bridges. These include the Burnett River Bridge at Bundaberg, the Victoria Bridge in Brisbane (which is no longer there), and the Lamington Bridge in Maryborough (built in 1896). The Lamington Bridge was special because it was the first bridge in Australia made with a new type of reinforced concrete.
How Was the Gairloch Bridge Innovative?
The Gairloch Bridge was built five years before the Lamington Bridge. It shows one of the earliest times concrete was used in bridge building in Queensland. Before reinforced concrete was used in Australia in the 1890s, concrete in bridges was mostly for strong, solid parts. These included un-reinforced supports (abutments) and pillars (piers).
The concrete pillars and supports of the Gairloch Bridge, designed in 1889, are among the earliest known in Queensland. After c. 1890, it became easier to get Portland cement made locally. This made using concrete in bridge building much more common.
Designed for Floods
The Gairloch Bridge is a special type of bridge called a "submersible bridge." This means it's designed to go underwater during big floods and still survive. It was the first submersible road bridge known to be designed by Brady. He is known for his important work in developing this type of bridge.
Building shorter, submersible bridges was a cheaper option than building very long bridges high above flood levels. Long bridges often had to cover a large area on both sides of the river. The main problem with submersible bridges was that flood debris could get stuck against them. This, combined with the force of the water, could cause serious damage. Brady created designs to prevent debris from getting trapped and to let floodwaters flow through easily. Even today, it's still common to design less important bridges to handle being submerged by floods.
Unique Design Features
The Gairloch Bridge had several new features for its time. For the bridge's surface (decking), Brady used 33-foot (10 m) long pieces of steel trough plate. These were 12 inches (300 mm) deep and joined together. They were then bolted securely to the concrete supports. The troughs were filled with tarred metal. The edges and posts were made of strong hardwood.
Brady believed this design had important benefits during floods. It was heavier, and the steel troughs meant there was no need for large support beams (girders). This made the bridge offer less resistance to the flow of floodwaters. This design cost more than a bridge made with traditional timber, but Brady argued it would cost less to maintain over time. The Gairloch Bridge is the only known road bridge in Queensland with this specific design.
Challenges and Repairs
Even with its clever design, the bridge didn't work perfectly at first. On June 11, 1892, a newspaper called The Queenslander reported that it needed "rather a large amount of money to keep it in repair." A major flood in 1894 caused two sections of the iron troughing to lift up and bend. This meant the entire roadway had to be rebuilt with layers of concrete and tarred metal.
Then, in 1927, a record-breaking flood completely destroyed the northern road leading to the bridge. In 1929, the bridge's roadway was resurfaced, and the hardwood curbing was replaced with concrete.
Later Bridges
Because the bridge often went underwater, it caused problems for people. This led to the building of two higher bridges across the lower Herbert River. One was built in 1927, connecting Halifax with Macknade and Ripple Creek. Another was built upstream from the Gairloch Bridge in the late 1960s.
Despite its early problems, the 1891 low-level bridge has lasted a long time. This is because of its smart design, which allows floodwaters to pass through with little resistance. The bridge is still used today.
What Does Gairloch Bridge Look Like?
The Gairloch Bridge is a simple concrete bridge that sits low over the river. It doesn't have fancy decorations, posts, or railings.
The top part of the bridge looks like a flat concrete slab, about 5.7 metres (19 ft) wide. The road on top of this slab has concrete edges and is covered with worn bitumen. At each end of the bridge, there are two reflective guide posts fixed into the concrete edge, one on each side of the road. If you look underneath the bridge, you can clearly see the steel plates that form its base.
Fourteen concrete pillars hold up the bridge. These pillars get a little narrower towards the top and are curved in the direction the water flows. Each pillar has a wide raised band at its bottom and a narrow band at its top. The cement in the pillars has worn away a bit, showing the small pebbles that are part of the concrete mix.
At the southern end of the bridge, the road goes through a deep cut in the land. The sides of this cut are lined with sections of brick, stonework, or loose rocks. Some of the stonework and bricks are covered with cement.
The bridge crosses the Herbert River at a spot where, for most of the year, the river is wide but quite shallow. Thick plants and trees cover the river banks at both ends of the bridge.
Why Is Gairloch Bridge Important?
Gairloch Bridge was added to the Queensland Heritage Register on July 17, 2008, because it meets several important criteria.
The bridge shows how Queensland's history developed. The Gairloch Bridge, built in 1890-1891, is important because it shows how North Queensland was settled in the late 1800s. By the late 1880s, the Herbert River valley was one of Queensland's most important areas for growing sugar. This bridge was the first one across the lower Herbert River. It was built to help farmers on the north side get their crops to the port. So, the Gairloch Bridge is closely linked to the start of this important industry in northern Queensland.
As an early, experimental submersible bridge, the Gairloch Bridge also shows how bridge design changed in Queensland. It's an example of how engineers dealt with the extreme conditions of the wet season in North Queensland. Submersible bridges became a cost-effective way to cross rivers that flooded heavily each season. They are still common in Queensland today.
As one of the state's oldest existing bridges that uses concrete, the bridge also shows how concrete started to be used in bridge building in Queensland. The Gairloch Bridge is an example of the earliest use of concrete, where it was only used for parts that needed to be strong under pressure, like pillars and supports. When reinforced concrete was introduced a few years after this bridge was built, concrete could be used for even more parts of bridges.
The bridge shows the main features of its type. The Gairloch Bridge is important because it shows the main features of submersible bridges. It is a low bridge that only crosses the main part of the river. It is designed to offer the least possible resistance to floodwaters and floating debris.
The bridge is also important as the earliest known example in Queensland of a road bridge designed by the famous architect and engineer, AB Brady. He designed the bridge soon after he became the Engineer of Bridges in the Department of Mines and Works. Other important bridges designed by Brady include the third Victoria Bridge in Brisbane (no longer existing) and the Lamington Bridge in Maryborough (1896, Lamington Bridge).
The bridge shows great creative or technical skill for its time. The Gairloch Bridge is important because it shows a high level of technical innovation for its time. The main special feature of the bridge is its top structure. Steel troughs were placed lengthwise on concrete pillars to form the bridge's surface. At the same time, these troughs also acted as strong support parts. This meant there was no need for large support beams (girders), which helped reduce how much the bridge blocked flood debris. The design is also new for its early use of concrete in the pillars, supports, and other structural parts.
Engineering Heritage
The Gairloch Bridge has been recognized for its engineering importance. It received an Engineering Heritage Marker from Engineers Australia as part of their Engineering Heritage Recognition Program.
