![]() The stone arch technology provides a cost saving of 80% compared to concrete or steel bridges and can be implemented by a public tender procedure. ![]() This gives local governments autonomy and allows them to upgrade more rural roads without increasing their budget. This avoids the need for complicated design and precision sensitive execution of steel and concrete bridges.Įnabel chooses this cost-effective technology to achieve the same positive outcomes as with more conventional concrete or steel bridges, without the need for significant financial support of the central government. Both the design and execution rely on simple rules of thumb that have been tried and tested through time. The Fabricius bridge in Rome for example has two arches spanning 24m each and dates from 62 BCE. Stone arch bridges have been built for more than 2000 years and some of the early structures are still used today. People dig them out and try to resell them to make a bit of extra money. In addition, such prefabricated elements are sometimes stolen. These frequently break during rough transport over bad roads from industrial centres and, because they are relatively light, they run the risk of being washed away during floods. Masonry bridges also avoid some of the disadvantages of conventional alternatives, such as the use of steel or concrete culverts. ![]() This leads on average to a reduction of 80 to 85% in construction costs, and a 50 to 80% reduction in carbon emission due to lower use of cement and reinforcement steel, when compared with conventional construction techniques. The stone arch technology capitalises on this fact by using readily available local materials in a labour intensive process. However, in rural Tanzania, it is very expensive to use industrial materials, while labour is cheap. These techniques require a high input of industrial materials and a low amount of labour. The commonplace technology for bridges is either concrete or steel.
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