The availability of relevant local culture, indigenous practices and knowledge combined with new ideas in technology and science can generate successful sustainable community development through innovation. Indigenous knowledge will not only contribute to the success of intervention, but better still its sustainability into the future. Numerous indigenous communities worldwide have always developed, operated and acted to different life challenges using indigenous methods passed on from one generation to the next.
Our main focus in this paper will be to study and design a simple bridge, highlighting the use of relevant traditional and indigenous knowledge and cultural heritage amongst the Aboriginal people and technology to create a way across the Nebine Creek. Introduction Access to the Bendee Downs site requires vehicles to cross the Nebine Creek which remains impassable during the wet seasons. The site is a ten hour car trip from Brisbane, the closest city with a major airport, and can be accessed via the Murra Murra Road off the Balonne Highway or the Munda Munda Road and east via Fernlee Road.
Nebine River is approximately twenty meters wide. The bridge design would respect the Nebine Creek’s cultural importance to the Kooma People; it provides a place where they can identify with their homeland and share their culture hence should be protected (EWB Challenge, 2010). The property has become a conservation icon for the region due to its conservation values. About 40km of the Nebine Creek flow through the properties and it has a 4km permanent waterhole behind the old homestead.
During the rainy seasons, the wetlands render the river impassable yet still it hosts a vast diversity of birds and fauna hence rendering it regionally, nationally and internationally valuable (EWB Challenge, 2010). Our design had to borrow much from the indigenous knowledge of the local community in conserving the site to design a technologically sound bridge. The following were considered in the design process: • The maximum load it can support at the middle. • The maximum load divided by the weight of the bridge (a measure of efficient use of materials) • Aesthetic appeal of the final project to give the conservation efforts a boost.
• The materials to be used. We settled on locally available materials like wood to make it affordable and to make use of indigenous knowledge. The design process was geared towards solving the problem of impassable road by building a beam wooden bridge that would be capable to allow even small vehicles to go across. This was supposed to present a creative solution and involve teamwork in implementing the design. Background Information Indigenous knowledge, sometimes referred to as ‘local knowledge’, ‘traditional science’ or ‘folk knowledge’ is a form of knowledge that is unique to a culture or society.
It is passed from generation to generation by word of mouth and cultural rituals and has been applied in almost all forms of life including cooking, health care, agriculture, conservation, education and several other facets of life that have sustained societies the world over. The indigenous way of practical learning has been interrupted by the abstract form of formal and academic way of learning witnessed presently (Fien, 2010). As the indigenous knowledge disappears, with it goes the valuable knowledge about ways of living sustainably.
In order to fulfil our objective of the design project, first we sought to find how the Aborigines lived and travelled in the past. This we did to help us understand the local conditions and provide a productive context for our design to help the community. Traditionally Aboriginal people carried as little as possible in their journeys and usually chose implements which were multi-purpose. They would revisit favourite campsites of previous years where they had left that were too heavy to carry. These items would be left closer to water so that it wouldn’t need to be carried far.
The women carried items on their heads and would make a ring shaped cushion of human hair, manguri, to wear when carrying heavy loads such as a big wooden dish etc. Men sometimes after hunting would carry a kangaroo on their heads. They carried their babies in a pouch in the back of a possum skin cloak (Berowra Valley Regional Park, 2010). This knowledge was very important in choosing the best type of bridge. Types of Bridges Several types of bridges are in existence today such as: Beam Bridges, Box Girder Bridges, Arch Bridges, Truss Bridges, Suspension Bridges, Cable Stayed Bridges.
Examples of these bridges are included in the appendix Beam Bridges A beam bridge is very simple. The farther apart its supports are, the weaker it becomes. Although the beam needs careful design, it is cheap and easy to manufacture but this compromises on its beauty. Box Girder Bridges This is similar to the beam bridge but with a girder, box shaped, which makes it stronger. The girder needs careful design; it is cheap and easy to manufacture but not very beautiful. The performance of a beam bridge can be improved by using supports i. e. arches, trusses, cables. Arch Bridges
Being one of the oldest types of bridge, they have great natural strength. Instead of pushing straight down, its weight is carried outward along the curve of the arch to the supports at each end. These supports or abutments carry the load and keep its ends from spreading out. Although they are heavy, they are strong if well designed and can be very beautiful. Truss Bridges Truss bridges are mostly empty space, but very effective. They are made of thin triangulated assemblies of metal members. They have a very good strength to weight performance and can be incorporated into any design.
They are usually very beautiful. Suspension Bridges A suspension bridge as its name suggests, suspends the roadway from huge main cables extending from one end of the bridge to the other. All the highly stressed parts of a suspension bridge are in tension apart from the towers. These cables which rest on top of towers are secured at each end by anchorages. They have a high aesthetic value, are light and strong. They span greater distances, are expensive and are susceptible to wobble if designed improperly. Cable-Stayed Bridges The cables are attached to the towers which bear the load alone.
They are very beautiful and require less cable. They are easier and faster to build but require stronger towers. Core Material – The design process Design of an arch bridge. Initially, a suspension bridge and other options were considered but because of the sandy nature of the place and foundation limitations, we decided on an arch bridge. We set to design a timber bridge over the Nebine Creek not only capable of carrying pedestrians and animals but also motor vehicles. This bridge would be built on concrete and stone abutments for the many girder span designed.
Instead of pushing straight down, the weight of the bridge (mainly made of laminated softwood) is carried outward along the curve of the arch to the supports at each end. These supports or abutments carry the load and keep its ends from spreading out. The abutments should carry a span of 22 meters. Four pairs of wooden beams, running lengthwise to the in relation to the bridge i. e. ‘longitudinal’, will rest on hammerhead bearings. The wooden beams are made of wooden pieces put in layers and glued together to form a larger beam.
The layers, which are glued laminated wooden beams to make them more durable, are laid horizontally to form the main beam. Each pair measures 1 meter by 0. 5 meters, 15 centimetres thick. The span is 22 meters. The beams are to be made of softwoods like pine which are readily available in the community. To hold the pieces together firmly, metal brackets would be used to bolt the pieces together. On top of the stringers, small pieces of timber would be laid across and a coating of asphalt pavement would provide the road wearing surface.
Since the stream has high banks and can hold rising waters caused by a flash flood during the rainy season, a concrete and stone arch bridge was chosen. The goal was to maintain the level of the road to allow for maximum potential stream flow. Traditionally, each family amongst the Aboriginal people would have a canoe, made from a single sheet of bark heated under low temperatures and then bent into shape. These canoes were used for fishing and crossing rivers especially during the rainy seasons.
A base of clay built in the bottom of the canoe, would be used to light fire to cook some of the fish caught from the river. The remainder of the fish would be brought ashore to be shared amongst the rest of the people. Crossing rivers, they would put logs across minor streams and sometimes large rocks would be used (Berowra Valley Regional Park, 2010). Examples of these are shown in the appendix. A simple model would be made of wood to test the usability of the bridge. A bridge plan diagram was drawn to determine the amount necessary; this was done by tracing on the arch at the bottom with a pencil.
On the model, an allowance of 10 inches is left from the end of the boards on the bottom cut to allow plenty of support on the stringers to carry the weight of the bridge. The amount of arch on the model was determined by using tack and string to make the arch. Wood glue is used to attach the pieces together, the cut out pieces are attached to the top of the stringer with a bead of wood glue and small screws (they are put on the underside so that they do not show. The pieces are then brought together to form the model beam.