| HISTORY OF THE YAMBA AREA
In 1799 Matthew Flinders, on his voyage in the sloop "Norfolk", set foot on the land where Yamba is now sited. However, he cannot be credited with the discovery of the Clarence River as he did not notice the river mass behind "Shoal Bay" and he reported the area as "deserving of no more than a superficial examination". He did note the superior hut construction techniques of local Aborigines.
Richard Craig was a convict who escaped from Moreton Bay and made his way south to Port Macquarie (1831) and then Sydney. It is said that for a pardon and 100 pounds he guided the cutter "Prince George" to the Big River where sands of red cedar grew right to the waters edge. The "Prince George" did not cross the bar into the river but the Captain confirmed the existence of a river on his return to Sydney.
With cedar supplies in the Sydney and Illawarra districts running very low, Thomas Small built a 52ton schooner, the "Susan" and acting on Richard Craig's advice he decided to head for the "Big River" in search of cedar. The first settlement was made on Woodford Island and in June 1838 the "Susan" was loaded with its first cargo of cedar for Sydney.
The Clarence was navigable by vessels with 13 feet draught as far as Grafton (originally known as The Settlement) and to Copmanhurst, 68 miles from the river mouth, by smaller craft. With an established New England wool industry, a number of large grazing properties on the Upper Clarence, the timber industry and an emerging fishing industry, the possibilities for import and export were recognised from the very early days.
In 1853 the Government agreed to set up a pilot station on the southern headland. Work commenced on the river breakwaters in 1862 and a variety of projects have been instigated to improve the river for navigation and establish port facilities since that time. The town was listed in The Australian Handbook, 1885 as:
"Clarence River Heads, or Yamba, a post town with telegraph office in the county of Clarence...It is a customs and a pilot station. Number of inhabitants in the district 340. There are two inns and lock-up and police quarters, and two stores. The Clarence steamers are the means of reaching the metropolis. District pastoral, of sandstone formation. The bar at the Heads has been the scene of many shipping disasters...A new breakwater is now in course of construction (Howland, 1999:1)."
There are two theories as to the meaning of Yamba, a commonly accepted one being that it is the aboriginal word for "headland". However, J.S. Ryan, following R.L. Dawson's early Recollections and Records of the Clarence aborigines, believes the most likely derivation is an aboriginal word yumbah meaning a rough edible shellfish the size of a man's hand that clings to rocks and is similar to an oyster (Howland, 1999:25).
Until the mid 1900s the busy river was the focus of transport and economic activity since poor or non-existent roads, extensive areas of lowland submerged during frequent floods meant that downriver towns like Yamba and Iluka were virtually inaccessible by land. So people went shopping or visiting or fishing by rowboats; sailing craft transported timber; sea going paddlewheel and screw ships shared the waterways with boat-hauled trains of sugar cane barges, ferries and cream boats.
The best known early river boats were the Iolanthe which did the run from Grafton to Clarence Heads from April 1886 and the Woolwich which ran from Grafton to Chatsworth. At one stage the South Grafton storekeeper, Mr J. McKittrick, owned both boats but later sold out to Captain Charles Pullen who had begun a service in the early 1880s with the Ethel and Young Dick. Captain Pullen bought up additional vessels and for 60 years the Pullen fleet plied the river, providing commuter services, morning and afternoon, between Grafton and the Heads, with link services along the south Arm and Coldstream river between Brushgrove and Maclean. Early boats included Lady Beatrice, Atlanta, Otis and Clarence.
The largest and most popular was the Favorite which went into service in June 1915 with Captain Tom Cooper at the helm and the Brushgrove band, augmented at Lawrence, supplying the music on her maiden trip to Yamba. Many local residents still recall the pre- World War II service provided by the steamer Moongi, skippered by Captain Cooper, and the diesel powered Mulgi, skippered by Captain Bobby Miller, with the steamer Mooli working the South Arm and Coldstream. The Mulgi was the last boat in service, but she too was withdrawn in 1941 because faster road transport had taken over almost all the passenger and most of the cargo traffic (Howland, 1999:75).
Yamba was an isolated outpost for the first 50 years of its existence because of poor accessibility by road. In early days in order to avoid the unbridged rivers, channels, creeks and low-lying marshlands travellers took the present Grafton to Coffs Harbour road as far as Glenugie, crossed the Coldstream river upstream at Sandy Crossing, passed inland by Tucabia, Summervale and Taloumbi, and reached Yamba via Pippi Beach; a detour of up to 40 kilometres. Gradually ferries and later bridges were provided; but it was not until 1898 that embankments and bridges were built at Romiaka and Micalo Islands, and not until 1911 that Oyster Channel was bridged. To add to driver's problems the roads were in places badly corrugated, or boggy, or sandy, or puncture-prone because oyster shells from aboriginal middens were used as a base. Until the 1920s service cars were often bogged or held up by punctures. In fact, it was not until the 1930s that the road from Grafton to Yamba was sealed, the concrete section around Ulmarra being built in the Depression to provide relief work for the many unemployed in the district. It was 1957 before the road to Yamba was fully sealed; and extensive upgrading is still going on in the Romiaka and Oyster Channel areas that caused so much trouble in earlier days (Howland, 1999:79).
HISTORY OF REINFORCED CONCRETE BRIDGES IN NSW
Structural Advantages of Reinforced Concrete
Prior to the application of concrete, the primary materials used for bridge construction were timber, masonry and steel. The use of concrete was promoted over the other building materials for several reasons including the increased strength, reduction of construction costs and time, lower repair and maintenance requirements, and aesthetics (Ring, 1913:2-3).
Reinforced bridges were also promoted as requiring little repair and maintenance. Concrete was seen to be waterproof, wind resistant and required no painting, which was one of the disadvantages of steel bridges (Ring, 1913:2; Faber, 1929:15; Lanchester, 1929:25). Concrete was also promoted as being fireproof, which was an important factor in rural areas, though it can be affected by extreme heat.
With a reduction in the volume of material and repair costs, reinforced bridges were considered to be more cost effective in comparison to stone or steel constructions. The construction cost of a reinforced concrete bridge, when compared to its construction in stone, was considered fifty per cent lower (Lanchester, 1929:25).
Another advantage of reinforced concrete promoted in the early twentieth century was its suitability for a greater range of bridge types. Lanchester identified that out of the four main bridge types, including arch, beam, cantilever and suspension, only reinforced concrete was suitable for all types (Lanchester, 1929:23). For arch bridges, stone, steel or reinforced concrete could be used, but for the other bridge types, stone could only be used for the abutments and piers with the remaining elements requiring steel and concrete.
Disadvantages with the use of reinforced concrete were attributed to poor workmanship, construction of reinforcements and costs associated with the temporary timber supports and formwork (Ring, 1913: 2). The structural integrity of the bridge depended on the proper positioning and quality of reinforcements, which once embedded into the concrete, were not visible. The need for temporary timber supports was seen as an uneconomical expense, though balanced by the overall saving of the construction compared to the use of masonry (Ring, 1913:2).
Once the strong compressive strength of concrete was recognised, the material was adopted for bridge design (Faber, 1929:16). The use of reinforced concrete allowed a heavier dead load when compared to the use of masonry. The use of steel reinforcements allowed a reduction in the thickness and weight of the girders when compared to steel bridges. The width of piers was also reduced when constructed in concrete, which allowed for wider roads and less impaired waterways (Ring, 1913:2). As less material was required for the overall construction of a reinforced concrete bridge, advocates of the material often promoted the possibility of "light and graceful" designs compared to bulkier masonry structures (Ring, 1913:2).
In New South Wales, most of the reinforced concrete bridges were concrete slab or concrete girder constructions. The first slab construction was the bridge over American Creek, Figtree in 1914 which has since been replaced (O'Connor, 1988:42). Other slab and girder constructions included bridges at Mullet Creek near Dapto and Throsby's Creek, Newcastle in 1916 (Evans n.d.:6).
The first continuous girder bridge was Fullers Bridge over the Lane Cove River that was designed in 1916 and completed in 1918 (Evans n.d.:6). Another major engineering achievement was the construction of the Roseville Bridge, which spanned Middle Harbour. Consisting of six 12.19 metre spans, it was considered the longest reinforced concrete bridge in NSW when it was completed in 1924. A continuous girder structure, Roseville Bridge was also supposedly the first bridge to be supported on reinforced concrete piles instead of timber piles (Evans n.d.:7).
The Public Works Department (PWD) was responsible for bridge construction until 1924, when the Main Roads Board was formed. Bridge construction was limited in the period between World War I and 1924.
Bridge Designs Between 1927 and 1947
Upon the transfer of Spencer Dennis from the PWD to the Department of Main Roads (DMR) as Bridge Engineer in September 1927 the design of concrete and other bridges began in earnest. The Department developed five designs in reinforced concrete that became more or less standard practice for the next 20 years.
Slab bridges
These types were found economical for spans not exceeding 6.1m (20ft) for simply supported bridges and 8.23m (27ft) for continuous and framed bridges. Some typical examples of this type of bridge were built at Marrangaroo Creek (1929) on the Great Western Highway, Raglan Creek at Kelso (1930) (figure 2), Kangy Angy Creek (1933) on the Pacific Highway near Wyong, the Eucumbene River at Kiandra (1935), the Crookwell River at Crookwell (1934) and at Tenterfield Creek (1939) on the New England Highway.
The simply supported slab bridge design was popular because even though the volume of concrete was greater than in other designs, the simplicity of formwork, false-work and reinforcement more than balanced the expense of the extra concrete required. Bridges of this design were still being constructed in the more remote areas of NSW in the 1970s.
Simply Supported Girder Bridges
The most common type of bridge built in the period under consideration was of slab and girder construction in which the slab carried the load to the longitudinal beams and was integral with them. The simply supported girder bridges were economical for spans up to 15.24m (50ft) after which the dead weight of the girders increased rapidly.
Continuous Girder Bridges
The DMR commenced building continuous girder bridges in concrete in 1933. This enabled the intermediate spans to be made longer and more economical than simply supported girders. The girders were usually haunched at the piers to provide for the high compression forces that occurred there. The parabolic shaped haunches gave these bridges an attractive appearance and many were built up to the 1940s when higher labour costs caused the false-work and formwork costs to be much greater in comparison with the saving in concrete. Some typical examples of early continuous girder bridges are at the Cooks River at Campsie, the Cataract River near Appin and the Bemboka River near Bemboka (Evans n.d.:11).
Framed Bridges
Another type of bridge to be constructed in this period was the framed bridge, where the abutments were framed into the superstructure thereby giving a very cheap and simple abutment. The construction of these bridges necessitated the presence of rock foundations at the site. A good example of this type of bridge was over Grubbenbun Creek at Lyndhurst which had a span of 16.76m (55ft). At the time of its construction in 1933 it was the longest concrete span built by the DMR.
Arch bridges
The few arch bridges built in NSW in this period were significant due to the variety of types used. A tender for construction of the first concrete arch bridge over Koorelah Creek between Tenterfield and Woodenbong was accepted in December 1929 and the bridge was completed in 1931. The bridge had a span of 48.76m (160ft) and was an open spandrel arch of the barrel type. It was designed by A Halvorseth, and constructed by W.L.Jemison for the amount of 8,729 pounds. Almost simultaneously another barrel arch was constructed over Walkers Creek (now Kitty's Creek) on the Barton Highway. This had a span of 18.29m (60ft) and consisted of a slab arch with the road embankment continued over it, the arch being splayed towards the springing to contain the increase in width of the embankment at natural surface level.
Two concrete bowstring arch bridges of 34.13m (110ft) span were designed by A.T.Britton in 1932 (figure 4). One was constructed in 1935 at Shark Creek on the Pacific Highway near Grafton by the State Monier Pipe Company and the other over Hillas Creek on the Hume Highway near Tarcutta in 1938 by E.V.Mather. No further bowstring arches were built probably because they were uneconomical when compared with conventional slab and girder bridges and could create a problem if future widening was required.
The last arch span bridge to be built in this period was at Galston Gorge in 1937. It was an open spandrel ribbed arch of 25.6m (84ft) span and was ideally suited to the gorge site which provided structurally viable sandstone for foundations. The designer was A.Halvorseth (Evans, n.d.:12).
The deck level of the structure has a clearance of 4.7m above high water level, enabling fishing launches and other small craft to pass beneath the Bridge when it is closed to larger vessels.
Most of the simply supported girder bridges were of single or two span construction but several longer bridges were built a notable one being the bridge over the Turon River at Sofala (1930) which had four 15.24m (50ft) spans which was built by the State Monier Pipe Company. The through girder type bridge which enabled longer spans to be built (up to 25m) without having to raise the deck level were not common, the most important example being the bridge over the Tuena River on the Bathurst to Goulburn Trunk Road No.54 (figure 3), designed by the prominent Norwegian engineer A. Halvorseth. This bridge had spans up to 18.89m (62ft6in) in length and was constructed by J.A. Jackson and Sons at the cost of 8,013 pounds in 1931 (Laws, 1931:75).
HISTORY OF OYSTER CHANNEL BRIDGE
The route to Yamba was established in 1898 when embankments and bridges were built at Romiaka and Micalo Islands, and Oyster Channel was provided with a vehicular ferry as a temporary measure.
As it proved unable to cope with the increased traffic flow, the ferry was replaced with a timber beam bridge constructed in 1911 by Kennedy and Ward (Howland, 1999:79).
When completed the Bridge took on a humpback profile which had several advantages over the horizontal structures that were more generally in use. Initially at the centre it provided a clearance of 3.0m above high water level, enabling fishing launches and other small craft to pass beneath and also it allowed rainwater to run off the roadway easily preventing it from pooling on the Bridge. However, based on the recollections of a long time resident of Yamba road, Mr Ted Kempnich, it appears that this bridge was not well maintained as:
"from my house I could hear cars coming from a long way off because of the corrugations and that the rattle of the boards on the old Oyster Channel bridge could be heard for miles away when Billy Eggins's service car crossed (The Daily Examiner , 21 June 1985)."
As a consequence of a decline in the serviceability of this first bridge work on the new bridge was commenced in 1936 at a new crossing of the channel 200 metres to the north. The realignment of the approaches involved the placement of embankments into the existing waterway and the substantial build up of the ground level as the road progressed through tidal inundated wetlands. The tender for the construction of the realigned approaches was won by Model Homes Pty Ltd and the erection of the Bridge was undertaken by the Department of Main Roads (Main Roads, 1937:126).
The timber beam bridge was demolished upon its completion and the girders and other remaining timber members on the old approaches were given to local property owners for fencing materials. Several piles were left in position on the Maclean side of the channel for a brief period for mooring purposes prior to their removal. |
